Hydraulic seal US-21X32X10-NBR90

What is a hydraulic seal? 
A hydraulic seal is a pressure seal, for a rod performing a translation. Mostly used as piston seal, cylinder. 
How to read the reference of a hydraulic seal? 
Example: 
US-40X50x7-PU94 
Where 
 US = Form of the hydraulic seal 
40X50x7 = inside diameter X outside diameter X thickness 
PU = material 
94 = Shore hardness   Shore hardness is a scale of material hardness. The higher the number, the harder the material. 



How to read the prefixes (informs the shape of the joint) of a hydraulic seal? 
 US = U-shaped groove, where the 2 lips are similar 
UP = U-shaped groove, where the inner lip is longer 
UT = "U" groove, where the outer lip is longer 
UTL = Throat "U", where the outer lip is longer, with secondary lip on the inside. 
UB = Solid seal. 
UC = Similar to US, with an O-ring inserted into the throat.
How to read the suffixes of a hydraulic seal? (type of rubber) 
FOR OILS NBR = Nitrile = Butadiene rubber - Acrylonitrile 
        from -30°C to +120°C PU = Polyurethane
        from -30°C to +100°C FPM = Viton = Fluorinated Rubber
        from -20°C to +200°C FOR BRAKE FLUID AND WATER  EPDM = Nitrile = Caoutchouc Butadiène - Acrylonitrile
        from -40°C tu +150°C FOR MORE DETAILS ON MATERIALS, RESISTANCE, AND LIMITS OF USE, REFER TO THE FULL DESCRIPTION ON THE SEALED SEARCH PAGE 
What is the difference between PU94 and NBR? 
 These are the 2 most widely used rubber in the hydraulic world. 
Both materials are ideally suited to hydraulic oils.   The NBR seal is more flexible, and agrees to be folded into the slot. Generally black at 123Bearing.   The PU94 gasket will be hard to accept high pressures (usually 30 more than the NBR). However, he can not be bent for his pose. Generally blue in 123Bearing. 
What difference in US, UP, UT?
 The US shape joint is the most common, and the most versatile. Refer to the following table for details on the form:.   US = U-shaped groove, where the 2 lips are similar 
UP = U-shaped groove, where the inner lip is longer 
UT = "U" groove, where the outer lip is longer 
UTL = Throat "U", where the outer lip is longer, with secondary lip on the inside. 
UB = Solid seal. 
UC = Similar to US, with an O-ring inserted into the throat.