Introduction to several common cylinder sealing rings, sealing principles and characteristics of cylinder sealing rings

Do you know what the common cylinder seals are? Do you know the application range of common cylinder seals? Let Shenwei Qidong tell you!


№1 Dust ring
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- Application scope:
- A2 type dust ring is used on the axial movement rod, plunger and sleeve of the cylinder.


№2 Guide belt
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- Application scope:
- Working temperature: -100℃ to +200℃
- Surface speed: ≤10m/s
- Permissible unit load at operating temperature ≤100℃=2.5n/mm2
- Medium: compressed air (oil-lubricated or dry, oil-free) (after initial lubrication).

№3 o-ring
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- Application scope:
- Polyurethane O-rings can be used when the physical properties of other O-rings cannot be met. Mostly used to seal cylinders, control components and valves.
- Working pressure: ≤600bar*
- Operating temperature:
Hydraulic: -35℃ to +100℃ water hfa and hfb liquid: -35℃ to +50℃


Pneumatic: -35℃ to +80℃
- Surface speed: ≤0.5m/s
- Medium: hydraulic oil (mineral oil based), hfa and hfb liquids.

№4 Buffer Seal
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- Application scope:
- Working pressure: ≤16bar (the pressure rise due to the buffering process has been taken into account)
- Operating temperature:
Standard material n3589: -20℃ to +80℃
p5008 polyurethane: -35℃ to +80℃
- Speed: ≤1m/s
- Medium: lubricated gas, dry gas (initial lubrication is required).

№5 Piston rod seal
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- Application scope:
- Working pressure: ≤160bar (hydraulic).
            ≤16bar (pneumatic).

- Working temperature: -35℃ to +100℃ (hydraulic).
-35℃ to +80℃ (pneumatic).

- Surface speed: ≤0.5m/s (hydraulic).
            ≤1.0m/s (pneumatic).





The sealing of the cylinder is divided into dynamic sealing (sealing of rotating or reciprocating parts) and static sealing (sealing of stationary parts). The requirement for sealing is to ensure both sealing and effective sliding friction. Therefore, cylinder sealing is very important for the cylinder. Below, Sunway Pneumatic will introduce to you the sealing principle and characteristics of cylinder sealing rings.






1. Classification of cylinder seals
There are two major types of sealing elements commonly used in cylinders, one is compression sealing rings and the other is pneumatic sealing rings.

2. The sealing principle and characteristics of compression sealing ring
Compression sealing ring When the sealing ring is placed into the sealing groove, there will be a certain amount of pre-compression, and the leakage path will be blocked by the contact surface pressure on the sealing surface, such as O-shaped and square sealing rings.


(1) Cylinder sealing principle and characteristics
1. The greater the pre-compression amount, the better the sealing performance, but the greater the friction resistance;
2. Can be sealed in both directions.

(2) The shape and characteristics of the sealing ring
1. O-ring seal
It has a simple structure, easy installation, small space occupation, low price, large starting friction resistance, requires lubrication, and short service life.

2. NLP type sealing ring
It takes up little space, has low sliding resistance, and does not require oil lubrication.

3. No oil is supplied to the cylinder piston.
It has compact structure, low friction resistance, good low-speed operation, grease-retaining lips, and good durability.

3. The sealing principle and characteristics of air pressure sealing rings
Air pressure sealing rings rely on air pressure to press the lip of the sealing ring against the sealing surface to ensure sealing, such as lip seals.

(1) Cylinder sealing principle and characteristics
1. The higher the air pressure, the better the sealing;
2. It can only be sealed in one direction, and the lip has a certain compensation effect on wear.