O-Ring

Since the O-rings are cheap and simple sealing elements they have a wide application area in hydraulic and pneumatic systems. In case of providing suitable working conditions and equipments, they can be used both in static and dynamic applications. Because they occupy less space and provide two sided sealing compared with other sealing elements, O-rings enable easy designs. Having good results from O-ring applications is up to suitable measurements, choosing correct material, and proper surface quality of metal parts.

STATIC SEALING
If there is no permissible gap in static applications, for O-rings there is no certain pressure limit to resist against. But, it is required that tolerances should be chosen correctly and xing screws should not create any gaps by extending in high pressures.

Static Pressure	Hardness
P ≤160 Bar	70 Shore A
P >160 Bar	90 Shore A

DYNAMIC SEALING
They are used in low dynamic pressures and similar others like pneumatic cylinders or valve spool.

Dynamic Pressure	Hardness
P ≤63 Bar	70 Shore A
P >63 Bar	90 Shore A

SURFACE ROUGHNESS
The other two most important factors in dynamic and static sealings are housing and the surface quality worked on.
For dynamic applications, a better surface quality is required compared with static ones.

Application	Surface	Rmax.
Dynamic	Piston	≤4 μm
	Rod	≤2 μm
	Groove base	≤6 - 1.2 μm
	Groove flanks	≤25 μm
Static	Sliding surface	≤10 μm
	Groove base	≤25 μm

RECOMMENDED CROSS SECTIONS IN DYNAMIC OPERATIONS
d1	d2
9	1.78
8 19	2.40 and 2.62
18 40	3.00 and 3.53
37 130	5.33 and 5.70
110 150	6.99