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 .