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

Minimum Order: 1 sets

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