Foam seal characteristics and uses

Foam seal is to use some of the material properties of a seal pores appear through its internal processing . Into EPDM (EPDM) foam seal , silicone foam seal , PU foam seal . Microwave curing process forming a smooth surface appearance, no pick marks. With good flexibility and resistance to compression set resistance, excellent anti-aging properties . Excellent flame retardant , low smoke and low toxicity ; stable product performance, size, high accuracy .

A foam seal features:
1 , lightweight and has high toughness ;
2 , insulation, low thermal conductivity , superior insulation ;
3 , having a non- absorbent closed cell structure , water absorption is low;
4 , excellent cushioning property impact resistance, can be used as a cushioning material ;
5 , excellent weather resistance high security cable seals. EPDM sponge by the Department of ozone test (50pphm40 ° * 72 hours).

Second, the use of foam seal :
1, the packaging material ( precision machinery, medical appliances, furniture , glass or the like cushioning material transport , small electrical protective cushioning materials, etc.)
2 , civil engineering, construction ( residential with a large plate sealing materials, sealing materials residential doors and windows , anti- shrinkage concrete liner material , an open channel caulking materials, various civil construction caulking materials, etc.)
3 , the vehicle , vessel ( door seal material , sealing material luggage compartment hood cushioning pad , various pipe sealing materials, sealing materials lamps , engine vibration materials, equipment category buffering and sealing material )
4 , thermal insulation, thermal insulation ( coolers and air conditioners use insulation sealing materials , refrigerators and freezer insulation sealing materials, etc.)
5 , noise, moisture ( noise abatement sealant various models of equipment, residential soundproofing wall sealing materials, all kinds of electrical appliances waterproof sealing materials,security stickers machinery and equipment for moisture sealing material ) .

How to do maintenance of automotive sealing strip

On the doors, windows and skylights edge of the car, we find that the presence of the sealing strip . These less from the eye of the sealing strip, is often in the summer, the owners were easy to overlook vehicle maintenance issues .

It is well known automotive sealing characteristics because it has only played a gum seal . If the seal long-term exposure , it is easy to aging , cracking, sealing performance is compromised , not only affect the sound insulation inside the environment,amper seals there will be severe leakage, seepage and other phenomena . Automotive beauty experts have pointed out , to do maintenance work seal , vehicle owners should start from the beginning of the everyday little things : The first step is to do the cleaning job seal , the owner can be every one or two quarters of the car seal for a cleaning . Concrete can be rubbed with a clean wet sponge rails, dust groove on , then wipe dry sponge once more to keep clean the sealing strip . The operation is quite simple , the basic need to dedicated car wash can be carried out .

When using high-pressure water washing If so, remember not to water sprayed directly at the seal , or easy to make ring deformed under high pressure water jet impact , over time will affect the sealing performance of the seal , the car is more easily into the water. In addition , car owners have to pay attention to the parking place . When faced with circumstances require prolonged outdoor docked , the vehicle should try to avoid direct exposure in the sun , if you can , the best vehicle for covering some reflective sewing to prevent the doors , skylights edge seal due to heat deformation and cracking.

If it can not be avoided Fixed Length plastic seal, do not splash through direct physical cooling methods , the larger the temperature difference tends to change the internal structure of the seal , resulting in deformation cracking.

Do not use frozen snow pretty trick car

After the snow in order to avoid embarrassment , the first frost, the main attention to the car before it is frozen , freeze several parts of the car's afraid of :
1 , some non- electronic remote lock keyhole first class attention , especially after rainy and snowy weather earlier , the owner of a piece of cloth wrapped around advance or paper wrapped about the keyhole in the car , this can be avoided As the frozen block keyhole .
2 , plastic vehicles often use seal parts : such as door seams , sunroof, trunk , etc. is easy because of the impact of frozen brittle , misuse can cause some unnecessary small abrasions. If forced open , then the owners will lead Mifengbuyan , causing leakage and leakage .
3 , the wiper will not be used due to snow cover and , of course, in the winter, car antifreeze , motor oil should be more than the lowest temperature weather , so as to ensure the normal road car , diesel car owners have to open the corresponding reducing diesel label , avoid direct damage to the oil freezing .

Impulsive one : windows, doors were forced open frozen
After the snow, the car is easy to crack, because the residual snow leading to the door open. See here some owners will say up pouring hot water can , in fact, this is not very secure, and even the owner of a day to drive to the snow , this is a very undesirable way . Because the fits and starts , then it is easy to damage the door seal and paint will therefore subject to different degrees of damage.
When the door was frozen encounter , the owner can try if you can open the door there , if there is a door can be opened , then all problems can be solved, car owners can use a hair dryer so heating equipment or direct start up the car and so the water temperature enhance the temperature inside the car with air conditioning , so the door and other parts of the convergence of melting snow . If the doors are all frozen , the owner may consider preparing a small portable dryer or hair dryer . If there is no such device , the owner is best not to use too hot water to melt the snow around the door , with a dry cloth to clean the car door after door open . This process must be carried out quickly to avoid secondary freezing. Of course, the latter method is not very recommended.
Windows were frozen , then heated air conditioning is the best way . But in order to save fuel , owners of the best preparation for a northern snow shovel to remove snow vehicle first , and then the warm breezes of the window air conditioner residual ice .

Two impulses : Wiper is forced to use frozen
When the wiper is frozen, the owners do not hurry . Forced to use it, ranging from damage to the rubber wiper , causing trouble for future use , heavy electrical wiper burned directly , it can no longer be used completely .
It is a professional auto repair shop technician said that the wiper north, is the most easily damaged vehicle parts , vehicle owners after snowy flame alight , in addition to lock the door but also the wiper stand up , do not let it stick to the glass , frozen in trouble on . The second is often under freezing rain north , to de-icing snow shovel can be used as soon as possible , but do not use force wiper de-icer , so make your car 's wiper rubber parts of a gap , which is a lot of vehicle owners say they Wiper scraping a reason not clean water .
The technical staff to remind owners , snow thaw wiper Do not use hot water , hot water can easily lead to vehicle glass burst , wiper thermal expansion and contraction deformation. high security cable sealsThis time the owners still consider snow with warm air into the car and then slowly melting ice on the glass and wiper , is the best solution.

Impulse to three : car brakes are frozen forcibly
Many owners may be in the car this morning , just started to hear " bang" , which is above the ice after being frozen brakes or handbrake was forcibly detach the sound .
This case is so long , it is likely to pull loose brakes, affect the braking distance of the car. To remind the industry , which generally occurs after snow in the morning , the car will start when some difficulty , if the handbrake is frozen fit to your car, try to reverse gear oil, but there is no one to pay attention to the rear or objects . Frozen brakes , then the owner can take the stick to ice burst open .

Snow equipment recommended
A car , " raincoat" ,plastic padlock security seals which can effectively prevent the car cover car was frozen, but the drawback is the time will win more strenuous .
2 , snow shovel , preferably with a stiff brush . Effective de-icing snow , winter driving essential .
3 , car hair dryer , which can effectively remove the door gap snow .

Focus position of the vehicle which sealed

Focus position of the vehicle sealing the following areas:

First, the vehicle doors and windows sealed

Before installing the glass doors of the vehicle to clear the debris carefully notch within such as mortar, brick dust, wood, etc., should be placed carefully on the glass, ensuring that both sides of the gap is uniform and timely than the positive fixed to prevent collisions shift deviate from the slot center. Rubber seal can not pull too tight, cutting length longer than the assembly length 20-30mm. When installing the mosaic in place, flat surfaces, and glass notch in close contact, so that the glass surrounding the force evenly. In the corner of the rubber should be beveled off and disconnect the injection of glue at the firm. When caulk sealant fixed glass, you should use rubber or rubber block glass and choked, leaving voids plastic injection, plastic injection depth should not be less than 5mm, before the glue curing, the glass should be kept free from vibration.

Second, the leading edge of the vehicle seal, the seal along the side edges and

Support from the hood, on the bonnet leading edge, a trailing edge and side edges of the body of the anastomotic site and paste, can the gap between the hood and the body effectively sealed vehicles on the way, can accelerate the air from the intake gate through the improved thermal performance. At the same time, you can reduce the hood and the front part, the friction between the left and right front fender, reducing noise and friction caused by the bump. If the gap is large, you can paste layers.

Three, four slits seal between the door and the vehicle body

Four of the gap seal between the door and the vehicle body, the vehicle can improve the sealing performance, reducing wind noise. Improve sealing performance can also prevent dust, rainwater into the cockpit to improve the efficiency of air conditioning and refrigeration. Carefully coated with special glue on the inside of the door, will cut a good seal side also coated with special glue, then along the inside of the door ring seal affixed.

Fourth, skylights and other components inside sealed

On the roof around the paste, can effectively improve the seal, dustproof and waterproof; wrapped pipes for air conditioning and refrigeration, can improve the cooling efficiency.tamper seal tape Between the door trim panels and the gap between the dashboard, storage boxes and other interior parts of the car, because the assembly and machining accuracy and other reasons, there is often friction, vehicle process will cause resonance at different speeds generate disturbing noise, which is generally very difficult to find. In fact, know the reason, as long as the seal to fill these gaps, paste.

Fifth, there is the door seal sealing flange

When the door flange seal repair, the repair should be noted that damage to the sealing flange, the flange accurately recover the original shape. After repairing the door seal to conduct inspection, inspection methods are: put a piece of cardboard in a sealed position, close the door, and then pull the paper, according to the Rally to determine the size of the seal is good. If the force required to pull the paper too much explanation sealed tight, it will affect the normal shut the door, and also due to deformation of the seal over the Omo rapid loss of sealing performance; If the force required to pull the paper through the small, indicating that the door seal seal bad, the wind will always be a door without rain phenomenon. metal security seal When replacing the door must pay attention to the inner and outer door panels in the new bite at the painted folding plastic cuffs and put some holes left when punching with the base tape blocked.

Do the above seal, your car will be able to rain or shine, for you to make the power of pleasures efficiency! In the rainy season will not shed tears for no reason!

The use of seals must be performed in strict accordance with the provisions of

Seals used in strict accordance with the provisions of the need to perform , so as to ensure the realization of the work and safety :
1 occurred due to mismanagement missing seals indicative seals , administrators reported within 24 hours of the leadership immediately to the responsible person penalty.
2 requisitioned for seals because the number does not match the number and use of , the reasons should be investigated and, if lost, the parties fines .
3 seals use the site and work orders , reports, lists any inconsistencies who the parties fines .
4 seals may not be lent to others , once discovered , unless the parties to write a written examination, depending on the seriousness fine , the circumstances are serious accountability.
5 pairs must be sealed without sealed or missing seal , or do not meet the technical requirements , carry out fine.
6 workers found counterfeit seal lead, after a verified determine fines against those responsible for causing serious losses bolt security seals, the transfer of the relevant departments in accordance with law .
7 seals seals staff are not free to disseminate to others, a seal was found to be seriously investigated management responsibilities.
8 due to poor infrastructure management and can not verify the seal number must be persons responsible .

Naming and models of wire and cable

Nomenclature and case :
Full name wires and cables are usually more complex, so people sometimes use a simple name ( usually the name of a class ) combined model specifications to replace the full name , such as " low voltage cables " on behalf of all the plastic insulation 0.6/1kV grade class power cable. Wire and cable type spectrum better, it can be said , as long as the written standard model specifications of wire and cable , cable tie wraps you can define a specific product, but it 's full name what is it ?
Wire and cable products, has named the following principles :
1 , product name , including the contents of the
( 1 ) the product or the size of the class name applications
( 2 ) the structure of the material or product type ;
Important features or additional features ( 3 ) product
The basic sequence named above , or sometimes in order to emphasize the importance of additional features , the feature is written before the front or the corresponding schema.
2 , the order of the schema
According to the principles described in the product structure from the inside out : Conductor - > Insulation - > inner sheath - > outer sheath - > armor type .
3 , simplified
In the case does not cause confusion , or to write some short schema province , such as automotive wire, cord aluminum conductors are not allowed , it does not describe the conductor material .
Case:
Rated voltage 8.7/15kV retardant XLPE insulated steel tape armored PVC sheathed power cable
"Rated voltage 8.7/15kV" - use the occasion / voltage levels
" Flame " - emphasizes the characteristics
" Copper " - conductor material
" XLPE " - Insulation Materials
" Steel armor " - armored material and type ( double strip gap wrap )
" PVC jacket " -self-locking cable ties  both inside and outside sheathing materials ( both inside and outside the sheath material as the sheath material written Province )
Name of product categories - " power cable "
Model corresponding written as ZR-YJV22-8.7/15, model wording see below for details.

Video capture spiral teach you install protective sleeve

In order to allow customers to better understand the protective cover screw mounting method ,security seal labels and yesterday afternoon we had a video shoot. Spiral protective sleeve installation method is very simple, simply, just two steps : First , fixed ; Second, Rao .

Our film crew being performed significantly associated with the DV shooting , I quickly snapped a picture of my own technology is not in place , you make do and see.

Here we talk about the installation method :

The first step , the first plurality of wires neat little confused a number , and then use the wire coil sheath middle position fixed ;

A second step , the electric wire along a fixed direction is wound , followed in another direction along the wound ;
Wound around the left side to the right

The third step, the protective cover all the coil ends in the external wire is wound , which the installation is complete .

Wire added after plastic protective sleeve coat , is not no longer seemed so messy , you can also save a lot of space. Spiral colorful protective sleeve also , if you install colored jacket ,high security cable seals it will change their surroundings , the color will glow with vitality it!

Working principle of the reactor mechanical seal

Usually the reactor has four mechanical seal sealing surface, i.e.:
(A) the reaction vessel sealing device between the stationary ring and the seat, the reactor is a static seal,nylon cable tie the gasket may be sealed using the general;
(2) the reactor stationary ring seal between the stationary ring seat and also the static sealing the reactor, usually flexible secondary seal to prevent leakage;
(3) reactor ring and shaft (or sleeve) between the seal, which is a relatively stationary seal used "O"-ring to seal. The above three seals are static seals, you can take measures to prevent leakage;
(4) Reactor moving between relatively rotating ring and stationary ring seal, are dynamic seal, is to rely on a spring loading device and media pressure on the opposite operation, resulting in the ring and stationary ring contact surface (end) on a suitable compression force,container seals so that the two smooth, flat end face close fit between the end face of maintaining an extremely thin fluid film (This film plays a role in balancing the pressure and lubrication end face) to achieve sealing purposes.

On the mechanical seals on rotating equipment applications and troubleshooting

Mechanical seal rotating equipment applications in a very wide range of mechanical seals sealing effect will directly affect the operation of the machine, will also appear serious major security incidents.
From the perspective of the mechanical seal internal and external conditions of the analysis of several factors and reasonable measures should be taken to affect the sealing effect.
Principles and requirements of a mechanical seal
Mechanical seals also known seal, indicative seal which is a mechanical means for rotating the shaft sealing means comprises at least one end surface perpendicular to the axis of rotation of the liquid is maintained at a pressure compensation mechanism and the spring force (or magnetic), and the auxiliary sealing action with Post consolidation relative sliding of the device to prevent fluid leakage. Its main function will be easy to change the axial seal leaks difficult end face seal leakage. It is widely used rotary shaft seal pumps, vessels, compressors and other similar devices.
Mechanical seal rings usually by the dynamic and static ring, composed of pressed components and sealing elements. One ring rotates with the shaft, ring and stationary ring sealing surface composed of tightly bonded to prevent media leaks. Ring seal chamber by the pressure of the liquid face pressed to the end face of the stationary ring and generates the appropriate specific pressure and maintaining an extremely thin liquid film on the end face two rings to achieve the purpose of sealing. Clamping element generates pressure, the pump is not running in the state,wire seals but also to keep the end face fit, to ensure sealing medium does not leak and prevent contaminants from entering the seal faces. From the gap sealing element and the shaft seal ring, the role of the stationary ring and gland clearance, while the elastic element to pump vibration, shock dampening effect. In actual operation of mechanical seals and other components are combined together to pump up the operation, the normal operation of the mechanical seal with its own performance, the external conditions have a great relationship. But we must first ensure their own performance parts, and technical requirements of the secondary seal installation, mechanical seals play its due role.

Self-priming pump mechanical seal installation elements

Check carefully before installing self-priming centrifugal pumps build adequate number of sealing parts, all components for damage, especially in dynamic and static ring without bumps, cracks and deformation and other defects. If you have questions, need to be repaired or replaced with new parts. Check that the hub or gland chamfer is appropriate, if not meet the requirements must be trimmed.
Mechanical container seals assembly of the various components and their related contact surfaces before installation with acetone or ethanol must be clean. Installation process should be kept clean, especially the dynamic and static ring and auxiliary sealing elements shall be free of impurities, dust. Dynamic and static ring coated with clean oil or turbine oil.
Gland on the coupling alignment should be performed after. Bolts should be tightened evenly to prevent the gland section skewed, with a feeler or a dedicated tool to check each point, the error is less than 0.05 mm. Check the gland and the shaft or sleeve OD with the gap (and concentricity), must be guaranteed four weeks evenly, with each point feeler tolerance is not greater than 0.10 mm.
Spring compression according to regulations, does not allow too large or too small phenomenon requiring error ± 2.00 mm in cross-section than the pressure increase over the General Assembly to accelerate the cross-section wear. Too small will result in less than the pressure can not play a role in sealing, spring after spring loaded seat to move flexibly. With a single spring to the attention of the spring rotation, the spring rotation axis of rotation should be in opposite directions. Fixed Length plastic seals Ring must remain flexible movement after installation, the ring is pressed against the spring should be able to automatically bounce back after.

Pump seal failure of the labyrinth seal and oil seal

In a properly designed, sophisticated processing, assembly intact, speed is high, with labyrinth seals with good results. However, in practical applications, the resulting leakage are many, of which the main reasons are:
1, sealing (such as shafts and bearing gland) with the gap is too large, and this gap is inversely proportional with the sealing effect. With the surface roughness,seal strap it is obvious marks spiral car in some cases also increased the leakage tendency.
2, the amount of grease into the bearing interior too, the overflow pressure exceeds seal resistance.
3, the oil window or the oil level gauge installation location is incorrect, misleading the people to the correct amount of lubricant oil chamber judgment.
4, the operation oil temperature reduces its viscosity, increasing the possibility of leakage.
5, the back tank or back to the hole size is too small, or by other obstacles, so that the liquid can not be blocked smooth return and cause leaks.

Oil seals
Self-tight seal is a lip seal, its simple structure, small size, low cost, easy maintenance, resistance torque is small, both to prevent media leaks, but also to prevent external intrusion of dust and other harmful substances, but also to wear have a certain ability to compensate, but the impatience high pressure, it is generally used in low pressure applications. Seal should be installed in the manufacturing precision of h8 ~ h9, the surface roughness of 1.6 ~ 0.8μm and after surface hardening treatment of the shaft. Sealing medium should not contain solid particles and impurities, which will cause rapid wear of the shaft seal and leaving the barrier seals failure.

Rubber O-ring plane static sealing introduction

Plastic and rubber looks a clear distinction between two kinds of substances or materials, it is not true ,numbered security seals they are the same substance in different rendering. They are polymers, and at a certain temperature conditions can be transformed into each other . This transformation temperature is the polymer glass transition temperature Tg, which is one of the characteristic temperature of polymer .
Tg is bounded to , polymers exhibit different physical properties : Tg less polymer material is plastic ; Above the Tg , the polymer material is rubber . From the engineering point of view , the glass transition temperature is the upper limit temperature engineering plastics , use lower limit of rubber .
If a recipe EPDM sample test measured by obtaining the glass transition temperature is -53.6 ℃, after the glass transition sample starts to melt ( elasticity began to recover ) , near the peak position at 31.4 ℃ . This peak temperature is the maximum melting temperature of the material at this temperature for maximum heat absorption , and thus also the largest of its expansion , the greatest contribution to the sealing .
January 28, 1986 , the U.S. space shuttle Challenger exploded, the reason is on solid fuel propulsion rubber O-ring seal structure caused by improper design :
1, O -ring material selection improperly ;
2 , the night before take-off extremely low temperatures , resulting in decreased elasticity O-ring seal compression decline ;
3, O -ring should be designed to the outside rather than the inside , as in the inside of the combustion and expansion of the metal rapid heat transfer , so that compression of the O- ring is insufficient , security seals resulting in tragedy. So the problem is not trivial seal , seal design or choice worth pondering.

Analysis of typical failure of the mechanical seal

General analysis of the mechanical seal common seal failure cause is usually experienced after analysis using derived through the process .
a. seal working gas shock ( splash and sputtering ) .
b. seal leakage and Grand icing .
c. steady drip sealing surface .
d. working seal screaming.
e. Gran outer ring graphite powder build-up.
f. pump and ( or ) axis vibration .
g. seal life is short.
Typical mechanical seal failure
General analysis of the mechanical seal common seal failure cause is usually experienced after analysis using derived through the process .
a. seal working gas shock ( splash and sputtering ) .
b. seal leakage and Grand icing .
c. steady drip sealing surface .
d. working seal screaming.
e. Gran outer ring graphite powder build-up.
f. pump and ( or ) axis vibration .
g. seal life is short.
Vaporization ( flash )
When the sealing surface friction heat accumulation , the end faces of the occurrence of local film boiling .
Symptoms seal pronunciation or take gas ( intermittent shock ) . Stationary ring bitten eclipse , comet -like texture generating process leads to a narrow ring outer edge trimming . Hard rings of thermal cracking . End at the inner edge of graphite dust accumulation .
Corrective measures checking seal design parameters ; improve circulation conditions .
Dry Running
Face between the liquid insufficient or no liquid.
Symptoms are severe wear stationary ring and groove . Hard surface polished ring marks, or radial cracks ( thermal cracking ) and discoloration. Aprons sclerosis. There LP graphite ring -shaped grooves.
Corrective measures chosen balanced seal ;releasable cable ties choose high thermal conductivity of rigid material ; Inspect the exhaust situation ; improve circulation conditions .
Blister scars
Between the end faces of the high viscosity fluid shear stress exceeds the breaking strength of the graphite . When the pump stops , the temperature drop of liquid viscosity increases so that the pump restart problems.
Symptoms of carbon graphite particles emerge from the end face ; hard ring with polished traces ; tiny gap in the residual graphite particles.
Corrective Action Check the loop condition ; using 15 ~ 30min ※ steam preheat or low pressure steam heat .
Abrasive wear
Grinding medium containing solid particles.
Symptoms of solid particles or residues accumulate in the face and tiny gaps , etc..
Corrective measures as using resistant material end ; improve cycling conditions : hydrocyclone , external cleansing rinse ......
Face deformation
Symptoms pump starts ,high security cable seals the seal leakage and leakage occurs over time. Will face light research on the platform , there are signs of deformation .
Corrective measures natural aging deformation, reground ; improper assembly , carefully re- assemble ; pump pair bad , bearing damage , adjust pump .

Industrial pump mechanical seal failure analysis of external causes

A large shaft axial channeling
Mechanical seal sealing faces have a certain pressure ratio , so as to play seal, mechanical seal which requires to have a certain amount of compression spring , a force to the seal faces , the sealing surface rotating together produce the desired ratio of the sealing pressure . In order to ensure that a specific pressure, mechanical shaft seal requires channeling can not have too much , generally guaranteed within 0.5 mm . However, in practical designs, due to improper design , channeling tends to have a great amount of shaft , the use of mechanical seals are very unfavorable. This phenomenon often occurs in a multi- stage centrifugal pumps , especially during startup of the pump , channeling a greater amount .
When working at the equilibrium balance disc and balance automatically changing the axial gap between the ring b, thereby changing the front and rear sides of the pressure balance disc , generates a force in the opposite direction to the axial force to balance the axial force. The inertia of the rotor runout and transient fluctuations in pump mode , operation will not be resting on a rotor axial equilibrium position . Always in balance disc ran around the state . In normal operation, the balance disc axial channeling is only 0105 ~ 011 mm, to meet the mechanical seal to allow the amount of 015 mm axial channeling requirements, but the balance disc in the pump start, stop , drastic changes in working conditions are likely when the axial channeling greatly exceeds the permissible axial mechanical seal channeling .
Industrial pumps after a long run, the balance disc and balance ring friction and wear , the gap b with increasing the amount of mechanical seal axial channeling increasing . The axial force on the suction side of the sealing surface of the pressing force increases , the sealing surface wear increased , until the sealing surface is damaged , lost seal. The discharge side of the mechanical seal , with the balance of the wear plate , the axial direction of the rotor member is greater than the sealing requirements channeling channeling the axial sealing surface of the pressing force decreases , id cable ties less than sealing requirements , the final side of the pump lost all mechanical seal seal.
2 axial force is too large
In the course of the mechanical seal is not able to withstand the axial force , if there is an axial force of the mechanical seal is serious. Sometimes, because of the axial pump unreasonable force balance mechanism design and manufacture , installation, use and other reasons , resulting axial force is not balanced out . Mechanical seals to withstand an axial force , the operation temperature is high gland , the polypropylene of the medium may be melted at high temperatures , thus the pump starts soon lost sealing effect of the sealing face when the pump is stationary there intermittent spray drain phenomenon .
3 shaft deflection is too large
Mechanical seals known face seal is a rotary seal axially movable contact , which is in a fluid medium and the role of the elastic member , the two lines perpendicular to the axis of the seal faces close contact , relative rotation , so as to achieve sealing effect ,security seal labels thus requiring two sealing force between to evenly. However, the unreasonable design of the pump , pump operation, the mechanical seal installation deflection generated at the larger the discontinuity between the sealing surface , resulting in good sealing effect .
4 no auxiliary flushing system or auxiliary flushing system set unreasonable
Auxiliary mechanical seal flush system is very important, it can effectively protect the sealing surface, for cooling , lubrication, and other debris washed effect. Sometimes designers no rational allocation of auxiliary flushing system , reach the sealing effect ; although sometimes designers designed the support system, but because there are impurities in flushing fluid , fluid flow, pressure is not enough, rinse mouth position unreasonable design and other reasons , also reach the sealing effect.

Power plants pump seal Precautions

According to the White Horse in Neijiang power plant pumps renovation and maintenance of such experiences , needs attention to the following matters .
Transformation can only be carried out in the positive pressure pump
If the vacuum pump ( eg fire pumps ) on the transformation , fillers easily sucked into the pump , stainless steel cable tie the White Horse stage steam turbine power plant has been transformed plant industrial pumps , supplementary pumps, circulating pumps , dredging pumps and boiler shop some of the low-pressure pump , running good effect.
Do not overtighten packing gland
After the installation of tight packing gland packing when not too tight , there should be loose.
Injecting a filler material so that the filler gun , according to the gland packing tightness to determine whether or filled . Tighten the gland by the loose , it means that the filler has been filled .
Filler added
Test pump, leak situation should be based on supplemental filler.
With the pump start , before injection of the filler of the rotary friction part will be extruded to the outside of the pump and generate a certain gap , resulting in leakage. At this time instant injection of filler until no leakage. Injectable fillers should be split into multiple transactions , action should be slow , at intervals of about 5min. If the packing is too tight and smoke , you can loose about packing gland, packing room while pouring cold water to cool . After a period of rotation of the pump , the filler and the sleeve has a good run , will no longer smoke.
Connector on the pump cover the requirements of the injection hole
Hole injection pump cover joints should closely,colored cable ties available raw tape winding , there should be soft gland gasket .
Filled with a filler after the injection pressure connector , and then tightly gland .
Injection can not be forced too fast
Filler gun high pressure ( up to 10MPa), therefore can not be forced when injected too fast , I feel a certain pressure to grip .

Vertical condensate pump seal transformation is widely

According to the customer's general response , the transformation has the following outstanding advantages:
A transformation of short implementation time - only in power plant condensate pump overhaul the way transformation, security seals almost no maintenance valid time
2 sealed high integration - an integrated part of the whole transformation only ( cartridge mechanical seal ) , a significant reduction in spares inventory , spare error rate is zero
3 does not modify the equipment original structure - the transformation only cancel the original packing and gland on the pump without any modifications , greatly reducing the risk of transformation , which in the initial implementation of the transformation of the unit is more important
4 reduces spare parts consumption - the seal life of four years , no longer need packing, bushings, and other spare parts inventory , reducing inventory capital
5 lower operating costs - because of mechanical seal packing friction power consumption is much lower than the friction consumption, increased running stability , reducing the running load , save operating costs
6 save labor - Routine maintenance is almost zero ,vehicle seals no longer have to frequent replacement of the packing and bushings .

Common seal rubber material introduced

NBR seals
1 , mainly oil resistance , abrasion resistance,cable tie oil resistance, widely used in applications that require high
2 common seals , O-rings commonly used materials
3 Operating temperature range : -40 ℃ -120 ℃
EPDM.
1 general acid -resistant , chemical resistance , chemical resistance , water resistance
(2) resistant to mineral oil, suitable for superheated steam (200 ℃)
3 Operating temperature range : -40 ℃ -120 ℃
Viton FPM (FKM, VITON)
1 oil, heat , acid and alkali resistance and excellent chemical resistance
(2) commonly used in high-temperature , corrosion-resistant occasion
3 Operating temperature range : -20 ℃ -210 ℃
Silicone MVQ (SILICONE)
1 heat, cold, tamper evident seal weather resistance and excellent resistance to compression set , good dyeing but poor mechanical properties impatience wear
(2) for high precision under low temperature sealing applications , are food, medical, widely used in the electronics industry
3 Operating temperature range : -70 ℃ -230 ℃

Waterproof sealing material in the construction industry in the application

When using a sealing material , seams on both sides should have waterproof grassroots , grassroots surface should be necessary processing , the proposed definition should include sealing material covering seal. Here we describe under the sealing material in construction waterproofing application .
A classification and role
Sealing material into shaped and unshaped ( paste ) two kinds . Stereotypes sealing materials including rubber water stop and water swelling rubber seal ; monolithic sealing materials include silicone sealants ,luggage seal polysulfide sealant category , polyurethane sealant, acrylic sealant, butyl-based sealant , modified asphalt sealing paste . Due to space limitations , this article focuses on the construction of monolithic waterproofing sealant application .
Integrity is waterproof layer must have the basic properties that can in reality there are various permeable waterproof layer seam sealing material should be properly applied to these permeable seams , waterproof layer on both sides of the joints are connected together , the sealing material serve as a bridge at the seams , by using a sealing material , with the integrity of the waterproof layer , the joint between the waterproof layer is watertight and airtight have , which is the true purpose of using a sealing material .
Sealing materials should meet two conditions:
( 1 ) shrink freely , fixed length plastic strap seal can adapt to and maintain an effective seal joint displacement amount of deformation ;
( 2 ) joint displacement process does not produce cohesive bond failure and destruction . In the construction waterproofing , the sealing material in the long-term flooding of the state , they should meet these two conditions .

Introduction of nuclear power shaft seal factory owners

Reactor primary coolant pump ( hereinafter referred to as the main pump ) is the heart of the reactor . Water filling the primary system , the use of dynamic driven main pump gas, before the heap in the open , using the master pump loop temperature reached 280 ℃ open heap condition .
In normal operation, the reactor coolant from the reactor effluent flows through the main channel into the steam generator, the heat is transferred to the secondary circuit water , and then pumped back to the reactor by the main loop through the main pump motor with large flywheel to increase primary pump idle time , maintain proper inertia , ensuring power outage core fuel elements will not be burned.
Qinshan one of the two main pump is a vertical , single suction, Francis , by the end of the pump housing and safety , the rotor components, shaft barrier seals parts, bearing parts, oil system , seal water and cold water system components located . Unit Total height 9.5 m, the reactor coolant water from the bottom of the axial , radial discharge levels from the drive end pump counterclockwise rotation.
Main pump shaft seal is a mechanical seal , the use of three identical hydrodynamic seal in series, the graphite ring material , stationary ring material is tungsten carbide, other static sealing material is EPDM.
Three-stage seal the pressure drop of the system pressure by 40%, 40 %, 20% to allocate , but each system -level design to withstand full pressure . Sealing pressure drop values ​​are assigned at all levels rely on stream -flow device festive controlled leakage flow to achieve the first stage and second stage sealed throttling device composed by two coiled capillary tube , sealed throttling device is the third level rely on a restrictor to achieve.
In all conditions, the shaft truck seal working life of at least 10,000 hours .

Porous mechanical seal Principle and Application

Car, that ring does not rotate, the spring force, the stationary ring plane static and dynamic sealing rings, so that the fluid medium to be sealed. When the ring rotates, the surface of the stationary ring has many pores, rotating ring and the stationary ring so that the surface pores on the surface of the fluid film formation convergence gap, so that each hole is like a micro power sliding bearings. That is, when the other end surface of the porous surface of the slide, the hole will be generated around the top and the fluid dynamic pressure, which is the fluid dynamic pressure effect. Fluid dynamic pressure bearing capacity depends on sliding speed, viscosity of the medium and the fluid film thickness. These holes generate dynamic pressure effect of the joint action of the result that the two sealing surfaces apart.pull tight plastic seals Since the presence of two fluid film between the seal faces, no direct contact with the two sealing surfaces, the sealing surface between the friction state of fluid friction. Experimental studies have shown that, in the face load and speed are the same, porous mechanical seal ring is always greater than the gap between ordinary mechanical seal the gap between the rings. End load increases, the ordinary mechanical seal ring end gap suddenly decreases, so that direct contact with the end face, film destroyed, so wear and tear. For porous face mechanical seal ring, end load increases, the end clearance is reduced, film increased stiffness, and also happens to be a small gap to minimize leakage to meet stringent mechanical seal leakage requirements, while reducing the sealing surface wear. Therefore, the porous mechanical seal can effectively prolong seal life.
Maximum PV value sealing mechanical seal is to evaluate the operational safety an important indicator of the porous mechanical seal mechanical seal can effectively improve the maximum PV value. Face of the porous ratio of hole depth and diameter to optimize the maximum PV value is about ordinary mechanical seals largest PV value of 2.5 times.
Thus, the porous mechanical seal can effectively improve the sealing parameters to ensure the safe operation of the mechanical seal. Porous mechanical seal has been applied to the petrochemical industry, stainless steel wire ties such as light hydrocarbons and toluene sealing medium at a temperature of 266 ~ 320 ℃, pressure 0.67MPa porous mechanical seal. After six months of actual operation, a satisfactory sealing effect.

Comprehensive interpretation of the corners of aluminum doors and windows and sealing the structure to strengthen

After curing epoxy adhesive inelastic, unable to adapt to the form of microseismic, easy crisp and broken, Corner after long-term strength is not enough, will produce cracking, dregs phenomenon. Colloidal slightly foaming during the curing process, expanded, forming metal to metal between the elastic pad, the effective transmission of forces weaken, play a shock, the cushion effect.
With the development of China's construction industry in recent years, aluminum windows and doors have also been developing rapidly. In the rapid development of aluminum windows and doors, while its quality problems are also increasingly prominent. The main questions focused on the quality of their profiles, heat insulation, metal parts and corners of doors and windows and seal strength. Today, we focused on those who use angle code attached to strengthen the corners of aluminum windows and doors often encountered problems with sealing talk about the view.
There are still a lot of people mistakenly believe that: as long as the production of aluminum windows and doors cutting high precision cutting equipment, angle code with the appropriate plus a fixed angle Corner unit, you can make the corners of aluminum windows and doors to achieve the strength and tightness requirements. In fact, most of the use of aluminum windows and doors connecting angle code is to use this process produced. This simple mechanical fixing of the connection is a rigid connection, it is difficult to adapt to windows in the production, transportation, installation, and long-term use encountered by force without being damaged.
First of all, we need to understand the physical properties of aluminum profiles.
Aluminum profiles and other materials, security seals like the existence of any thermal stress. Thermal stress refers to a material change in the temperature-induced stress, typically linear expansion / contraction coefficient.
We can calculate the aluminum alloy in the temperature range of the normal size change, that the linear expansion / shrinkage rate using the following formula: L = L0 (1 + ΑΔT) where: L: length after changing L0: original length, Α: the expansion / contraction coefficient, for aluminum extrusions, in -40 ° C +50 ° C range, the value is 2.4 × 10-5 / ° CΔT: the temperature (Celsius) changes in the value calculation example: aluminum alloy original length of 1 m, the temperature change is +50 ° C-40 ° C = 90 ° CL = 1M (1 +2.4 × 10-5 ° C × 90 ° C) = 1.00216M
That is: 1 meter long aluminum profiles in the 90 ° C temperature variation will produce 2.16MM length variation. Aluminum windows and doors for the corner only rigid connection strength is that this change will have devastating effects, so that doors and windows corner mutual position of the parts disorder or deformation, reflected in the corners of windows and doors undoubtedly fatal flaw . This defect is any bolts or rigid connections Corner machine is no way to make up.
Secondly, in the production of aluminum windows and doors, installation process, due to handling, transport, installation and construction errors when moving, as well as doors and windows installed, aluminum windows and doors to withstand long-term effect of their own weight, withstand window openings, building wall static deformation stress error,truck security seals switching windows, air pressure, environmental impact and frequency of sound waves of varying peak vibration, the vibration can sometimes induce resonance doors, impact on the overall strength of windows and doors.

Way to achieve zero leakage seals

Pros and cons of two-way seal can withstand radial loads and ensure bi-directional sealing performance. The seal is mainly used for fluid delivery systems, including a variety of medical and dental equipment . With 60 years experience in the production of indicative seals Minnesota Rubber provides bidirectional seal custom design .

In order to achieve zero leakage , Minnesota designed a special rubber lip seals , the sealing lip on one side exposed to the pressure in the positive direction , the other side in the opposite direction to withstand stress. Under pressure , the sealing lip of the seal to close the sealing surface and ensure that the liquid does not leak .

Excellent design , the correct choice of materials and precision manufacturing process for these lip seals deliver the best performance. For medical applications , Minnesota Rubber will choose special material, to ensure the final product low extractables , with most intravenous (IV) fluid system compatibility.

Lip seal size is also an important factor in sealing applications . The sealing member can be reduced smaller possibility of leakage . Minnesota Rubber can design and manufacture a variety of small size meter seals. For example figure parts, maximum diameter of 0.346 inches (8.788mm), an inner diameter of 0.140 inches (3.556mm), a height of 0.145 inches (3.683mm). Tolerance control : ID + / -0.004 inch (0.102mm), sealing surface diameter + / -0.005 inch (0.127mm), seal height + / -0.005 inches (0.127mm). Minnesota Rubber transfer molding using advanced technology and production equipment to ensure dimensional accuracy and product quality parts .

Mechanical seal on the pump shaft

Compare mechanical seals and packing , mechanical seal has reliable sealing , long life, low power consumption , the use of a wide range of advantages. Part of the early failure of the mechanical waterproof labels life is short, the main problem is the lack of design and manufacturing , often due to improper selection , spare parts of inferior quality , reasonable friction material selection , installation and maintenance shall not be law , sealing causes poor water quality . To extend the life of mechanical seals , need to design , manufacture, maintenance and use of all aspects of work together.
Mechanical seal design and modeling must be combined with the actual production situation , try to use reliable sealing, long-lived static friction materials and seal material . If double mechanical seal contacts the inner end of the media , in order to use corrosion resistant materials based ; does not contact the outer end of the media , in order to choose a good sealing reliability based materials , such as WC rubber rings , etc., are not necessarily consistent pursuit of inner and outer ends selection , both to reduce costs , but also increase the sealing reliability.
Mechanical seal parts machining quality must be strict requirements, specifications and maintenance procedures must be particularly set mechanical seal installation and use of technical requirements, so that rule-based workers .
Mechanical seal during use , is not necessarily a little on the high amount of leakage must overhaul. Sometimes after a period of time to run into the sealing surface of the dirt washed away , sealing water clean, running- friction , the temperature deformation eliminated, leakage will be significantly decreased. For double mechanical seal ,plastic seals  as long as they secure pressure , they can test for a period longer overhaul.

Mechanical shaft seal with them about

( 1 ) When the mechanical seal pressure medium, the pressure medium due to the end face than the pressure of its adaptation range is exceeded , will lead to film damage , causing heating and abrasion ; high friction deformation easy to make and fragmentation , so that the machine seal failure. Required to work under high friction material must have sufficient stiffness and strength , must be considered carbide , ceramic , ceramic spraying pressure and both high strength and stiffness of the material.
( 2 ) In the case of high- speed , linear velocity as the mechanical seal , the sealing surface to increase the friction heat and wear , the friction material should be a good thermal conductivity low coefficient of friction ceramic leaching copper and graphite .
( 3 ) When the mechanical seal in a hot environment , if not handled properly prone to the aging of rubber , part of the deformation , so that the mechanical seal leakage should be used in high-temperature materials, such as sintered alumina ceramic ( alumina ceramic ) , heap solder alloy and so on.
Machine graphite stationary ring quality does not meet the design requirements
Design requirements resin impregnated graphite stationary ring , but have a certain immersion depth. Sometimes impregnated graphite stationary ring is not deep enough , fixed length plastic strap seal that is impregnated layer remaining after machining rarely ; design requirements face some finish, but often fail to meet requirements spare finish ; design requirements purity graphite texture , and a certain hardness, and spare parts tend to have hard spots , hardness is not enough and so on. Resulting graphite wear very serious.
Improper selection of spring pressure machine
Mechanical seal primary seal point - dynamic seal point , is perpendicular to the axis of rotational movement of the ring end face and the end faces of the stationary ring by bonding together . The sealing end face of the spring clamping force is generated by the spring pressure , the low pressure seal faces is to start , run and stop lamination case always maintain a good prerequisite sealed state . When the seal face wear , by the spring pressure to overcome the friction of the shaft seal to ensure that ring moved axially face wear compensation , ensure the seal .
Since spring pressure value directly affects the size sealing reliability , such as spring pressure is too large ,wire seals the sealing surface overextended , increased wear and tear ; spring pressure value is too small , not well fit the sealing surface , the spring force to resist not within the gas medium pressure or face wear not compensated , resulting in mechanical seal leakage . Therefore, a reasonable choice of spring pressure value is the key to sealing reliability . Spring pressure is not enough, take the following two methods to eliminate leakage : ( a ) in the ring behind padded to compensate for the spring force . ( 2 ) with a spatula and abrasive scraping , sanding sealed chamber and the spring seat and "V" -ring with the Department , so that the spring force acting on the friction pairs tightly closed.

Rubber water-stop installation and construction methods and precautions

Rubber Sealing Strip is in the concrete casting process where some or all of the pouring buried in concrete, the concrete number of pointed stones and sharp steel head , the plastic and rubber tear strength than the tensile strength 3-5 times , water stop once it has been punctured or torn ,metal seal without a great outside external gap will widen , so the water stop position and concrete pouring process, should pay attention to positioning methods and pouring pressure to avoid sealing band is punctured.
1 waterstops shall prolonged outdoor exposure, to prevent rain , not with polluting chemical substances. 2 in the transport and construction, to prevent mechanical , steel damage water stop .
(2) the construction process, the water stop must be firmly secured to prevent displacement occurs in the pouring of concrete , waterstops in concrete to ensure the correct position .
3 Fixed waterstops methods are: use of additional reinforced fixed ; special fixtures ; wire and template fixed For perforation, the only election in the water stop edge of the installation shall not damage other parts.
4 user orders should be based engineering structures, calculate the length of the product design drawings , drawings shaped structure should be explained , as far as possible water stop at the factory will connect into a whole, for the connection of the site ,pull tight straps can be electrically heated plate vulcanizing adhesive together or cold adhesive ( rubber water ) or welded ( plastic water stop ) approach.

Work requirements for seals inventory

1 hardening (aging ) - One seal leak because its temperature material is hardened , when the hardness is too high ,pull tight plastic seals the sealing member can not be filled and with a gap between the parts , it will leak .
(2) Wear - wear of the seal surface of the part involved with the finish , velocity and transmission media , different sealing materials, adapted to different velocity .
3 Extrusion - when the seal to put too much pressure will be squeezed into the metal gap , damaged seals and cause leakage , this situation involves seals of their hardness and metal gap is too large, if in the design , selection , processed or handled properly installed , there will be out of damage.
4 Corrosion - the situation is manifested seals soften even dissolve , because seals invaded by the media , the choice of material error. If the aqueous or solvent media paying particular attention.
5 General seal according to the temperature ,strap seals velocity , pressure, and material can be used for the following simple classification ( for reference only ) : Temperature ratings apply material velocity pressure levels for materials for materials 110 ℃ nitrile rubber / PU 0.5 M / S nitrile rubber 200kg / cm2 with the hardness and design 200 ℃ Viton 0.6 M / S PU 400kg / cm2 with the hardness and design 260 ℃ PTFE 14 M / S PTFE 700kg / cm2 with the hardness and design more about "Hydraulic seals "

Polysulfide sealant Characteristics and Application of Technology

With China 's rapid economic and technological development of large-scale water conservancy project, the construction of high-rise buildings , aerospace engineering development and so need special properties of elastic adhesive sealant for joints , security seals sealing materials. According to reports , China's output of this sealant has reached 4 to 5 million tons, and formed a polysulfide , acrylic , silicone and polyurethane sealants as the main industries.
Polysulfide sealant is a polysulfide rubber (HS-(C2H4)-O-CH2-O-C2H4-SS) n-C2H4-O-CH2-O-C2H4-SH) -based agent , a plasticizer , reinforcing agents , curing agents made ​​of high-grade sealing materials. Because liquid polysulfide rubber polymer main chain containing "S" atom , forming -CS,-SS- chain and is saturated, which made the polysulfide sealant has excellent oil resistance , solvent resistance, aging , acid base properties, and heat, water , low permeability , good elasticity, for metal and nonmetal have a high bond strength. Mainly used for insulating glass sealing , high-rise building roof slab waterproofing and sealing subways, tunnels, sewage treatment plants, airport runways, large water conservancy waterproof seal joints . Therefore, there are broad application prospects.
Thiokol in 1929 successfully developed by the American company , in a solid state. Until 1943 improved synthesis process , made with a thiol end group of the liquid polysulfide rubber , have a rapid development. Since this polymer with various peroxides , oxide to cure at room temperature to form elastomers , thus expanding the range of its use .
Abroad in the 1960s polysulfide sealant in the automotive, shipbuilding , petrochemical and sealed waterproof construction work and other aspects are given a wide range of applications . Thiokol in our research work started late, until 1958 after the establishment of Jinxi Chemical Research Institute considered on track. Late 1970s early 1980s with the development of high-rise buildings , along with the rise of aluminum doors and windows was promoted polysulfide sealant waterproof seal in construction engineering applications .
The world production of liquid polysulfide rubber , the United States 20,000 tons / year, Germany 8000 tons / year, Japan 5,000 tons / year, Russia 3500 tons / year, Western Europe, about 2,000 tons / year. Chemical Research Institute of Jinxi only 500 tons / year scale devices can not meet the market demand, at present most of our imports from Japan , security seals the annual import volume of 1500 ... 1800 tons ; production of polysulfide sealant has reached more than 8,000 tons .

Impact of construction machinery hydraulic oil quality factor

The quality of hydraulic oil , not only affects the normal operation of construction machinery , id cable ties and may cause serious damage to the hydraulic system components . Now summarize the work practice in the absence of dedicated instrumentation several cases , simple identification of hydraulic oil quality.
1 water . The amount of oil in the water content of water in accordance with GB GB/T1118.1-94 technical standards, and tested its quality indicators should be not more than traces if excessive moisture in the oil , it must be replaced ; Otherwise , not only will damage the bearings , but also to rusty steel surface , thus the hydraulic oil emulsion , deterioration and a precipitate , hinder thermal cooler , affect the valve , reducing the active area of ​​a filter , increasing the abrasive action of the oil .
( A ) visual method : If the oil is milky white turbid , then the oil contains large amounts of water .
( 2 ) combustion method: using a clean, dry cotton or tissue stained with a little oil to be detected , then the use of fire to ignite . If you find " crackling" sound or flash the burst phenomenon , then the oil contains more moisture
(2) oxidation. General construction machinery hydraulic oil operating temperature of 30-80 ℃, hydraulic oil temperature is closely related to their work life , experience tells us that when working oil temperature above 60 ℃ , each additional 8 ℃, oil life is halved , that is the life of the oil 90 ℃ 60 ℃ about 10% of oil , because the oil is oxidized. Oxygen and hydrocarbon oils reacting the oil slowly oxidized, black color , viscosity increase , and finally could not be serious enough to oxide dissolved in the oil , and brown mucus layer deposition to somewhere in the system , easily blocked element in the control oil passages , so that ball , valve, hydraulic pump piston wear increased , affecting the normal operation of the system . Acid oxidation also cause corrosion . Slowly began to carry out the oxidation process , when it reaches a certain stage, the oxidation rate will suddenly accelerated, will follow the sudden increase in viscosity , resulting in working oil temperature , the oxidation process faster , the accumulated sediment and acid will be more Finally the oil can not be reused.
3 impurities. Impurities can not only wear the moving parts , but once they are stuck in the spool or other deputy campaign , you will affect the normal operation of the whole system , Fixed Length plastic seals cause the machine to malfunction.
4 air . If the hydraulic oil containing gas , when the bubble wall and the overflow will impact the formation of cavitation generated elements , so that the system does not work , a little longer will result in component damage .
5 . Chemical reaction. Tank shall be cleaned of paint , etc., can cause chemical changes in the oil .

Mechanical seals and hydraulic seals difference

People are generally very difficult to distinguish between the mechanical seals and hydraulic seals, often thought it was the same object.
First, talk about mechanical seals and hydraulic seals: Wikipedia
Mechanical seals are precision , structure is more complex mechanical component of the foundation , a variety of pumps, reaction synthesis reactor, turbine compressor , submersible motors and other key components of the device . Its sealing performance and service life depends on many factors , such as selection, the accuracy of the machine , the correct use of the installation .
Hydraulic seal pressure demands to have a combination of surface finish , use more rubber sealing element , through the seal to achieve local deformation of the sealing effect .
Second, the mechanical seals and hydraulic seals Category
Mechanical seal Model: cartridge seals series, light mechanical seal series , heavy mechanical seal series
Hydraulic seals : lip seals , V -ring , U -ring , Y -ring , YX -ring seals and hydraulic cylinder seals commonly used combination is mainly bud -ring cell to circle and Lancaster closure .
Third, how to choose the seals
Seals in the purchase of maintenance ,numbered security seals  most users will be according to the sample size and color to buy, this will only increase the difficulty of purchasing , but not necessarily be able to select the appropriate product. The following procedures are recommended to improve the accuracy of purchase seals :
1 the direction of movement - first determine the location of the sealing member movement direction , such reciprocating , rotary , screw or fixed .
2 Sealed focus - such as deciding the point of activity in the inner diameter of the rod seal or activity point is at the outer diameter of the piston seal.
3 Temperature Class - Instructions for use machinery from the factory to inspect or assess the actual working environment temperature, determine the required use of materials . For a description of the temperature level of production users can refer to the following precautions .
4 pressure levels - from factory machinery access to the relevant data for use , or by observing the original seals and structural inference softness working pressure rating, a description of the relevant pressure level production users can refer to the following precautions .
5 size - most users will by used to buy old samples ,security ties but seals in use for some time, will be the temperature, pressure and wear and tear and other factors significantly affect its original size, press the select sample only as a reference , a better approach is to measure the location of the metal seal tank size , accuracy will be higher .

Condensate pump shaft seal rehabilitation programs

Cancellation packing seal, no leakage lossless transformation of a single cartridge mechanical seal face .
Transformation of the condensate pump range:
a) The structure of the pump itself, without any changes , retaining the original sleeve , but to ensure sleeve diameter size φ120-0.04-0.08mm, outer surface roughness Ra of less than 6.3μm;
b) The outer face of the gland packing chamber by the two bolt holes increased to 4 , in order to ensure the mechanical padlock seal gland installation force uniform ;
c) cancel the filler , watershed ring, packing gland ;
d) retain the original outer loop piping system, which is only used at startup , normal operation can be shut down packing chamber cooling water ;
e) from the mechanical seal and flush mouth then a nominal diameter of 8 mm tube into the original relief holes , and install the valve control.  3 swing and ran on the mechanical shaft seal of LDTN type condensate pump for the vertical suspension mode , the pump and motor by the motor rotor weight borne Thrust above . Normal conditions , the upper and lower motor bearings and bearing fluorine resin condensate pump rotor pump only play the role of radial positioning , there is damage to the mechanical seal swing mainly radial and axial movement of the swing . If the radial and axial movement of the swing beyond the mechanical seal to allow beating range, it will damage the mechanical Fixed Length plastic seal. The following may occur for condensate pump two most harsh conditions the greatest impact on the mechanical seal , one is in the motor pump and motor shaft bearings as a fulcrum for the conical lower swing ; another is based on the lower bearing motor and pump heads fluorine resin bearings as a fulcrum for the arc-shaped swing.

Eliminate cavitation pump inlet measures

( A ) to improve the level of pump cavitation performance , cavitation field devices to meet performance requirements .
( 2 ) field test equipment required to pump cavitation performance level match.
( 3 ) on-site installation and regulate working conditions and create favorable conditions to give the pump numbered security seals .

Measures to eliminate vibration pump
( 1 ) pump assembly process, in strict accordance with standards and procedures to perform, to eliminate vibration source .
( 2 ) pumps, motors , base, on-site piping and other auxiliary equipment installed in the field , to strictly eliminate vibration sources.
( 3 ) on-site production ,tamper seal labels operation, maintenance , adjustment, strictly, to eliminate vibration source .

More teeth difference cycloid gear pump Knowledge Overview

More teeth difference cycloid gear pump ( also known as small teeth cycloid pump ) is 80 years abroad developed a new cycloidal gear pumps, slashing at the top of its non- mining Chuan complete isometric short Epicycloid curve for cycloid ( pinion ) tooth profile .plastic seals With phase conjugation using adjacent circular cross gear tooth root and the tooth after slashing the top of the arc for a tooth profile . There are two tooth difference , three teeth difference cycloid gear pump . Compared with the ordinary cycloid pump , it has a flow pulsation , large displacement , etc. .
Ordinary internal gear pump and multi- pump teeth difference cycloid tooth profile is very similar to the composition , such as tooth profile curve equation , the choice of the design parameters have similar laws Fixed Length plastic seal .
More teeth difference cycloid gearing major river in the hydraulic system of hydraulic pumps and hydraulic motors can also be used for planetary transmission .

Re- heat boiler tube wall comb through modification of the sealing plate

Comb-shaped sealing plate is modified reheat type folding comb sealing plate to locate the seal plate (12Cr1MoV, δ8), positioning the sealing plate processing when a uniform length and width of the plate after marking , according to the reheater pipe diameter (D64mm) drilled hole , and then follow the protective casing diameter (D68mm) machined counterbore depth of 3mm . Reheater embedded in the protective sleeve by positioning the sealing plate , to ensure the pitch between the tubes , reducing the swing tube rows . Meanwhile , this welded structure is simple, convenient , to further improve the welding quality, avoid the folding -type comb -shaped seal plate complex produced by processing and assembly difficulties deviation , thereby preventing the seal lower quality weld .
Installation of protective casing protective casing installation transition purposes : ( 1 ) casing material and its internal wall pipe of the same material , in order to ensure that the work of the tube with protective sleeve seam welded joints using the same kind of steel , will be transferred to the dissimilar steel welded joints with protective sleeve positioned between the seal plate welds , improved wall pipe work weld crack resistance ; ( 2 ) protection tube wall thickness thinner than the reheater tubes , which specifications for D68mm × 3mm, reducing its structural rigidity makes sealing welding deformation transferred to the casing ,indicative seals eliminating the formation of geometric stress concentration points , improved wall pipe work weld the force .
Construction should pay attention to the problems of access to the site reheater tube wall spectrum in addition to a 100% and 100% visual inspection , but also deal fillet weld pipe through the wall set at 100 % of the magnetic memory testing , to prevent unqualified ( exist melting wear , weld defects such as abnormal stress concentration ) pipe is used.
Note wall pipe positioning in the high roof pitch , the tube is in the process of looking for prohibited the use of flame cutting tools, in order to avoid the flame burn or cut high roof inside reheater tubes . Guaranteed replacement wall pipe before and after the reheater tubes mounted side elevation of the same, to prevent the tube rows down and obscure corner wall tube row spacing becomes smaller , resulting reheater appear swollen outer pipe blocked situation. As of May 31, 2006 , the 2nd boiler reheater wall pipe after 22961h and 24762h running test , the sealing structure fillet weld no cracking spill accident to 0.1 yuan / (kWh) of electricity generation efficiency calculations, due to wear caused by burst pipes forced outage one day loss of power caused by substitution are: 250,000 kWh × 0.1元(kWh) -1 × 24h = 60 Million / day Therefore, these measures effectively reduce the wear and tear squib the number of very substantial economic benefits strap seals .
Medium temperature, high temperature reheater wall pipe sealing structure optimization and transformation in reducing the number of burst pipes boiler repeatability and ensure safe operation of the boiler area , with significant economic and commercial integrated social benefits, while also having the same type of boiler better application value .

Severe vibration pump inefficiency how to do

Workaround: polyimide carbon fiber composite materials for the pump casing mouth ring and bushing. Running clearance by the API standard down to 0.0015 inches per inch turning diameter .
Results: The initial vibration 0.600 inches / sec ,pull tite seals improved vibration 0.094 inches / sec , efficiency 5%.
Vibration : the vibration decreases the following reasons:
1 ) recirculation flow and its destabilizing effects of the rotor decreases ;
2 ) reduce the gap , the axis running decreases ;
3 ) There are natural and easy injection performance thermoplastic material to absorb shock or impact .
Efficiency : reduced efficiency because the pump casing and the gap between the impeller ring . Here the pump turn will reduce the internal recirculation gap .
Reliability : This pump has been more than four years of continuous work , the refinery has also been the polyimide carbon fiber composite materials for use in more than a dozen stage pump.
Polyimide carbon fiber composite material anti- abrasive material characteristics and advantages of the application :
a. has excellent wear resistance in abrasive particles in the working conditions better than rubber, bronze , carbon, graphite and other materials.
b. widely used in sewage pump , sea water pump ( the work environment is sand and other abrasive grains ) in the bushings, bearings and sized pipeline pump wear rings .
c. use is only recommended as a fixed component ( due to material temperature limits ) .
d. compared to other non-metallic materials,bolt seal anti- abrasive composite has better chemical resistance .
e. compared to the rubber bushing and other metallic materials , carbon fiber composite material of polyimide material has a very low coefficient of friction .

Study abroad introduced for gear pump

Gear pumps for domestic and foreign research focuses on the following aspects:
( 1 ) Gear pump structure parameters and the optimal design of the basic design parameters of the gear pump determines the flow characteristics of the pump and the engaging performance index .truck seal Application optimization design method design parameters can be selected to meet the design requirements of gear parameters.
( 2 ) trapped oil shocks and unloading measure the phenomenon of trapped oil gear pump gear pump for the hydraulic system as a whole have had a lot of harm . Trapped oil shock and gear size and overlap factor unloading it completely and so have a great relationship ( including unloading slot position , shape and size , etc. ) .
( 3 ) the flow rate characteristics of the gear pump gear pump because a large flow pulsation , the pressure pulsation in some of the higher hydraulic systems , gear pumps rarely used . On reducing gear pump flow pulsation are already many ways , such as using composite gear pump ; reasonable choice of parameters gear ; using split gear.
( 4 ) new tooth profile of the gear pump technology research as computer-aided design and CNC machining technology rapid development , many of the past that is very complex surfaces in the design and manufacture of tooth profile becomes relatively easy. Thus, the emergence of various shapes tooth profile gear pump , such as linear conjugate tooth profile gear pumps , external gear type cycloid gear pump , and the outer envelope of the arc of the wedge toothed internal gear pumps. Straight tooth profile conjugate internal gear pump is considered to be the best overall performance ,stainless steel cable ties simple structure , displacement pressure , wide coverage, especially under high pressure , low noise and long life make it in the growing hydraulic technology figures prominently advantage position. Is Thus, for non- involute gear pump research is showing rapid development trend.
( 5 ) the characteristics of the composite compound gear pump gear pump gear pump can significantly reduce flow pulsation , but also has large displacement , small size , high mechanical efficiency , meshing force balance each other , etc. are taken seriously.

The use of diesel fuel pump maintenance considerations

1 , pump installation, to check the models, specifications are correct and clear anti-rust oil , the choice of gasket thickness should be appropriate to prevent excessive or too thick book the piston top dead or run in place , tighten the bolt tightening torque to evenly and prevent damage to the pump .
2 , pump the hand pump hand pump body between the piston and the rubber sealing device , do not arbitrarily dismantled, rubber Wai damage must be promptly replaced .
3 , within the coarse filter pump connector core vulnerable to dirt and clogged lint , etc. ,truck security seals should always check the cleaning, the filter damage must be promptly repaired or replaced .
4 , hand pump must be pushed back after use , the button tightened to prevent the hand pump and gasket or valve and the valve seat is not tight due to pressure caused by the intake or leaking.
5, to ensure plunger pump " four spring " flexible normal . "Four spring " for the piston spring , tappet ( wheel ) spring , inlet valve springs , delivery valve springs, elastic weakened or broken should be replaced or padded adjustments.
6, some pump casing has opened a vent hole , the hole is the role of a small amount of leakage pump diesel directly into the pump body. Holes shall not be blocked to prevent dilution of diesel into the fuel pump sump lubrication .
7 , to ensure that the entire gasket intact , plastic washers disassembly number should not be too much , and should be replaced periodically.
8 , found that diesel fuel injection pump sump too much , you should promptly check the pump piston and pump, tappet and tappet cover gap is too large, too large to be in time to prevent serious leakage due to diesel fuel , fuel pump and adjust the poor lubrication inside the mechanical speed .
9 , add diesel to be filtered through the sediment ,cable tie markers to ensure clean , and prevent excessive impurities exacerbated pump inlet valve , the oil valve seat wear , and sometimes even by impurities valve paving and failure.
10 , prolonged shutdown, preventing the pump mating surfaces , especially with the pump piston , tappet and tappet suite of water in the oil due to corrosion, rust measures must be taken ( downtime , replacement fuel pump sump inside with moisture , diesel oil and other impurities ) .

VRLA battery charge balance principle analysis

VRLA batteries ( hereinafter referred to as VRLA battery ) With saving investment , easy installation, safe, reliable, easy to use and other characteristics, in practical applications are heavily used. However, due to lack of understanding of its requirements and follows the old balance charging system, the battery causing great harm.
1 reason to cancel the equalizing charge
( A ) What is a balanced charge
The so-called balancing charge, the charge is balanced battery characteristics , is the process of using the battery , because the battery individual differences, temperature differences causes the battery terminal voltage imbalance , the imbalance in order to avoid deterioration of the trend , needs to improve battery set charging voltage , charging the battery activation .
( 2 ) the reasons for not equalizing charge
First, the concept of a balanced charge concept is used in the old-fashioned lead-acid batteries currently proposed large majority VRLA batteries are clearly stated, " voltage balance , into thoroughly ." The " battery acid layer is not formed , without the need for a balanced charge ." For single 2.4V battery charge voltage is defined as the charging speed , the "FASTCHARGE", rather than "EQUATION".
Secondly , a balanced valve-regulated battery charging will cause damage . Equalizing charge voltage for most batteries, are higher float voltage . At this point, most normal cells are in the overcharge status. The gas in the battery can not be combined within a certain pressure , the pressure control valve exceeds the safety threshold, the valve opens , the gas discharged from the control valve .
In previous battery maintenance , along with the process of equalizing charge the battery weight is adjusted such that the approach used to add distilled water add water , in order to maintain the equilibrium of the battery . However, the battery maintenance ,marker cable ties the maintenance of the existing system is water , and this way, water loss will inevitably cause the battery , dry battery .
2 Cancellation equalization charge, how to ensure the consistency of the battery terminal voltage
( 1) The battery terminal voltage determinant
Firstly, it is determined from the concentration of the electrolyte and the electrode materials . Cell dehydration , electrolyte concentration must increase , the battery terminal voltage increases. Secondly , the opening of the safety valve . If the pressure relief valve is too low, will inevitably lead to premature battery water loss , the terminal voltage rises. In addition , the series connection state between the battery is different, float occur when insufficient charging . When the battery is experiencing deep discharge recovery charge then , it is difficult to restore , this will cause the battery voltage is low.
( 2 ) the battery terminal voltage of assurance that
Since the battery terminal voltage will exist inconsistencies, do not allow battery equalizing charge , then the battery terminal voltage should be how to ensure consistency ? Should start battery raw materials, production processes to ensure the consistency of the battery voltage . The choice of materials such as batteries , in particular electrolyte plate , the pressure control valves and other key material selection .truck seal Second, we must ensure that the quality of the battery installed , ensure that the battery installed state consistency. For example, the battery connection method, such as the balance of torque . Also in the maintenance of attention. For some behind the recovery of batteries to be charged , but also properly adjusting the battery electrolyte ; should periodically check the pressure valve working condition.

Pump mechanical seal dimensional inspection should pay attention to several issues

1 , lubrication
The mechanical seal faces should be properly lubricated , thus reducing wear and prolonging life , some lubricant friction heat can also be taken away . Lubricants generally assumed by the media itself , thus sealing face ( ring, stationary ring ) see spring pressure should not be too large.
2 , flush cooling
Pump mechanical seal end face of the work so that the heat generated should be promptly passed out, otherwise it will vaporize liquid film between the end faces formed by dry friction, flush cooling measures must be considered .
Generally flush with internal coolant security seals sealing medium , may also have an external water supply cooling water. Should be used in mechanical seal flushing coolant absolute guarantee of supply and flush the coolant flow, if necessary cleaned regularly.
3, the old seal update
In contrast with the new mechanical seal better than the old , but the new mechanical seal quality or choice of material is not the time , with the larger size of the error will affect the sealing effect ; sexual penetration in the polymerization medium, the stationary ring without excessive wear, or not to replace as well. Because static ring stationary ring seat for a long time in a quiescent state , the polymer and impurities deposited as a whole, played a good seal.
4 , the seal overhaul
Once the mechanical seal leakage will be eager to overhaul , in fact , sometimes sealed and not damaged , tamper seal tape simply adjust the working conditions or the seals can be adjusted to eliminate leakage. This way to avoid waste and to verify their ability to judge the fault has accumulated experience in maintenance to improve the quality of maintenance .

Sealant Product Features

1 -component, moisture curing , facade construction is not flowing ;
2 flexible, good tack , moderate intensity ;
3 with glass,tamper evident tape aluminum and other materials, good adhesion ;
4 good sealing performance ;
5 interrupt when drawing gluing short ;
7 low volatile odor ;
8 excellent anti-aging properties:
Sealants used in packaging advantages:
Sealing a direct impact on packaging effect , packing and storage life , and even affect the credibility of the packaging . To this end , the sealing glue has become an important part of the packaging . Sealing material in accordance with the form and use can be broadly divided into gasket , sealing tape sealing and colloid and other categories , can reach to prevent liquid leakage , blocking oxygen, moisture , odor -proof forgery, counterfeit products are intended . Security seal , numbered seals sealed packaging in recent years the rise of technology, generally hot melt pressure sensitive adhesive tape or sticky point sealed envelope , packaging can not be dismantled once the restitution, thereby preventing counterfeit products appear to protect the interests of consumers.

Pump mechanical seal maintenance, overhaul should pay attention to several issues

1 , lubrication
The mechanical seal faces should be properly lubricated , thus reducing wear and prolonging life , some lubricant friction heat can also be taken away . Lubricants generally assumed by the media itself ,wire seal thus sealing face ( ring, stationary ring ) see spring pressure should not be too large.
2 , flush cooling
Pump mechanical seal end face of the work so that the heat generated should be promptly passed out, otherwise it will vaporize liquid film between the end faces formed by dry friction, flush cooling measures must be considered .
Generally flush with internal coolant sealing medium , may also have an external water supply cooling water. Should be used in mechanical seal flushing coolant absolute guarantee of supply and flush the coolant flow, if necessary cleaned regularly.
3, the old seal update
In contrast with the new mechanical seal better than the old , but the new mechanical seal quality or choice of material is not the time , with the larger size of the error will affect the sealing effect ; sexual penetration in the polymerization medium, the stationary ring without excessive wear, or not to replace as well. Because static ring stationary ring seat for a long time in a quiescent state , the polymer and impurities deposited as a whole, played a good seal.
4 , the seal overhaul
Once the mechanical seal leakage will be eager to overhaul , in fact , sometimes sealed and not damaged , simply adjust the working conditions or the seals can be adjusted to eliminate leakage. padlock seal This way to avoid waste and to verify their ability to judge the fault has accumulated experience in maintenance to improve the quality of maintenance .

Flat metal seal butterfly valve pneumatic Characteristics

In recent years, the use of butterfly of modern industrial development, extended from the low-pressure water to a temperature higher than 538 ℃, -184 ℃ low to medium pressure from low to high , widely used in air separation , chemical industry, metallurgy, sewage treatment and other fields. And caliber growing, higher performance requirements , require a longer service life .
Currently, the majority of domestic and foreign production of rubber sealing butterfly valve and plastic seals, easy to wear and aging , reach equipment for continuous operation cycles. In air separation , for example, today in cryogenic separation principle -based air separation plant , which processes are using molecular sieve pre-purification processes, working pressure of 0.5 ~ 0.9mpa, medium temperature range of 10 ~ 200 ℃, its switching valve used temperature, caliber , frequent switching valve rubber seals easy to wear and aging, but also more difficult to replace .
For these situations , developed a metal rod by force plane sealing pneumatic valve series. The new valve has been the national utility model patent ( patent number : zl97224037.3).
1, the metal flat sealing pneumatic valve characteristics
( 1 ) The lever hoist structure, so that the relative sliding between the sealing small decreases relative wear .
( 2 ) using the rod actuator force increasing mechanism . The butterfly valve is in the closed state agencies ,security ties the drive unit can output maximum torque , and has a self-locking performance , safe and reliable .
( 3 ) use of flat metal seal structure, with strong corrosion resistance and wear resistance, suitable for high temperature environments , long service life .
( 4 ) key components has been optimized so that the total of the valve opening and closing times can reach 1 × 106 times.
( 5 ) of the valve control system uses non-contact magnetic reed switch , from environmental conditions, and the signal sensitivity , high accuracy, can achieve remote control , pneumatic control and automatic control , and ancillary equipment can also be achieved without person operation.

Water pump mechanical seal Precautions

Water pump mechanical seal device , if used improperly installed metal ring seals can be easily damaged ,tamper evident tape causing the pump does not absorb water , the water shortage and other faults.
Therefore, use should note the following:
1, using the former must add enough water to prevent dry friction .
2 , If the pump is leaking from the pulley side , should immediately identify the cause and add oil.
3 , try not to smoke silt , weeds and more water .
4 , the impeller thin wall easily broken , if demolition should gently pry the impeller .
5 , check the rubber quality, installation is best dip .
6 , rotating bearing body , pull tight seal checking static ring and shaft with the gap , should be uniform . Such as static deflection ring installation should be corrected immediately.
Ready to clear the overflow hole , to prevent water from entering the bearing , diluted lubricant .

Diesel fuel injection pump and the reasons for exclusion Mifengbuyan

Diesel engine fuel injection pump and the oil is turned on, to form a sealed circuit , when the original body of the air , the engine should stop working for no oiling .
At this time, machine hand should first check the stock of diesel fuel in the tank , if exhausted , into the pharynx whether to leave the oil pipeline ; second is to check whether the fuel tank outlet is blocked , resulting in the formation of vacuum circuit can not supply , then the fuel injection pump bleed screw loose, hand pumps pump oil, if a large number of bubbles or oil foam appears and oil do not feel carefree ,cargo seals indicating low pressure oil are blocked , then check the coarse and fine diesel filter clear whether the blockage , tubing for cracks , touch deflated ; whether the tubing joints forget to install the gasket or gasket is damaged, causing a leak or the air intake .
When the hand pump oil pump , oil feels very smooth, but there is no pressure, which was mainly due to fuel pump relief valve in the oil return on spring break or fatigue deformation, wear or dirt ball paving and Mifengbuyan so low oil pressure oil supply shortage caused by low fuel pump . Check the return oil pressure relief valve sealing effect , hand blocked inlet mouth blowing , blowing does not move as normal, otherwise Mifengbuyan , hand pumps pump oil, the handle should feel a stretch tic pressure very easy to handle when opening or automatic back .
For the old-fashioned hand pump should also check the fuel pump inlet pipe to the fuel tank between the oil is blocked, if the majority is due to clogging pump inlet strainer below clogged by dirt or gasket damaged due. Hand pump oil pump shaft the handle when you feel no suction, when the handle is depressed , feeling great resistance , mainly between pump the oil to the oil pump clogged . Mostly due to fuel pump inlet screw with anti-loaded pressure relief valve , fuel pump in the non-return valve installed backwards or wear off very , hand pump aging damage rubber container seals and other reasons .
Such as fuel injector return pipe has a lot of bubbles appear , which was mainly due to a cylinder injector nozzle stuck in the open position , he went to the high pressure gas cylinder injection pump body . The oil filter return pipe connected at one end removed, blocked oil return port filter , bubbles disappear , indicating a fault in the fuel injectors, and then find which cylinder injector nozzle is stuck, be ruled out.

The valve sealing performance is very important

Sealing surface material and the processing status of the valve sealing performance of the sealing surface of the valve material and processing conditions have a significant impact leakage . As the remaining gap between the seal faces depends on the sealing surface micro-roughness , so that , if the use of steel materials, seals, resulting in sealing of the same , there must be greater than the pressure , the value must exceed brass system value than the pressure seal . The sealing surface of the processing state , such as a peak distortion , high security bolt seals and sealing the gap size changes and other phenomena occur on the metal surface , it is clear that the performance of the surface properties of the base material have significant difference . Induced changes in the machining surface can affect the thickness of 50μm. Grinding the base metal is not exposed . Work is different from the metal surface tissue matrix organization . Geometry and material properties and microstructure geometry compared to little effect . Differences in the performance of metal , usually less than other factors . Sealing surface when working under low pressure conditions , the situation is more prominent. When the pressure ratio is higher than 40MPa , the surface roughness of the sealing performance is reduced , and the impact of the material is increased.
Hydrophilic surface properties of the valve sealing surface of the leak amount of hydrophilic properties due to capillary effect. When the sealing surface as long as a thin film, the need to increase the pressure of the water through the gap . As the metal surface with good hydrophilicity, kerosene can easily penetrate the gap casting and sealing connection . So, in some of the most critical situations , is the use of kerosene for the hydraulic tightness test . Filling the cavities of kerosene tightness test method , equivalent to approximately 0.3 ~ 0.4MPa water pressure tightness test under pressure .
Properties of the medium on the valve sealing performance of the liquid medium is substantially on the leakage of the viscosity determined by the sealing valve in the same , the various conditions are the same , the viscosity of the medium viscosity smaller than the much smaller leakage medium . Gases and liquids compared to the difference more obvious ( except for saturated steam , saturated steam is easy to ensure the sealing surface ) .
The closing member of the rigidity and structural features of the valve closure member sealing performance and structure of the rigidity is due to the elasticity of the part . The closed valve closure member is not absolutely rigid , but has a certain flexibility in the pressure of the medium , the size is changing, which force causes the sealing surface interactions. To compensate for these changes on the sealing performance of the closure member , cable ties the sealing surface preferably has a smaller rigidity of the elastic deformation is as large as possible . Hope valve manufacturer importance of factors affecting the performance of the valve seal , the valve sealing performance caused by leakage minimized to prevent leakage and leakage within the valve .
The presence of the sealing film of the valve sealing performance of the sealing film exists between the sealing surface has a significant effect on its sealing performance . When the sealing film on the surface , the destruction of the contact surfaces hydrophilic , so that a larger pressure difference is required to make the medium passes through the pores . In addition , dense sealing film on the surface of the channel to plug the media travel , improve the connection sealing. In the use of film sealing should pay attention: When the work process film is reduced, should be able to recover the oil film thickness. Oils used in the valve being not soluble in the media , nor should evaporate , hardening or other chemical changes .