How to Select the Seals for Hydraulic Cartridge Valves

China [CN]

How to select the Seals for Different Hydraulic Screw-in Cartridge Valves?

Chinese Hydraulic Screw-in Cartridge valve manufacturer AAK often receives various questions from overseas customers, some of which even come from college students conducting academic research. Today, we will once again introduce the main materials used for seals in hydraulic screw-in cartridge valves, as well as their respective characteristics:

1.    Rubber Sealing Materials

1)    Nitrile rubber (NBR)

-       Excellent oil resistance, suitable for conventional hydraulic oil environments, with a working temperature range of -40 ℃ to+120 ℃.

-       Mainly used in static sealing scenarios, such as O-rings and some combination seals

2)    Fluororubber (FKM)

-       High temperature resistance (up to 200 ℃), chemical corrosion resistance, suitable for hydraulic oil containing phosphate esters or highly corrosive media.

-       Commonly used in high-pressure systems or extreme temperature environments.

3)    Silicone rubber (VMQ)

-       Outstanding cold resistance (-70 ℃ to+200 ℃), but low mechanical strength, only suitable for static sealing

2.    Polymer Sealing Materials

1)    Polytetrafluoroethylene (PTFE)

-       Extremely low friction coefficient, good self-lubricating properties, strong corrosion resistance, suitable for high-speed or chemically corrosive environments.

-       Often used as a filling material in conjunction with rubber, or in combination with seals (such as Glay rings, seals).

2)    Polyurethane (PU)

-       High wear resistance and anti extrusion strength, suitable for high-pressure reciprocating motion seals (such as Y-shaped rings, U-shaped rings), working temperature -30 ℃ to+100 ℃.

3)    Nylon (PA)

-       Oil resistant and wear-resistant, used for non direct sealing components such as guide rings and support rings, with a working temperature of -40 ℃ to+120 ℃.

3.    Metal Sealing Materials

Stainless steel/copper alloy

-       Used for extreme high pressure (>32MPa) or high temperature (>450 ℃) scenarios, achieving metal to metal sealing through precision machining.

4.    Composite Sealing Materials

Clip on rubber+rubber (lace ring) or PTFE+rubber (Glay ring/Steller seal)

-       Combining the elasticity of rubber with the wear resistance of PTFE/sandwich material, suitable for high-pressure dynamic sealing (such as valve spool and valve cage).

Selection Suggestions

-       Normal working conditions: Priority should be given to using nitrile rubber or polyurethane.

-       High temperature/corrosive environment: Fluorine rubber or PTFE composite materials are better.

-       Ultra high pressure scenario: requires metal seals or combined sealing structures.

AAK HYDRAULIC VALVES (844) 2025-03-17