Seals

5. Select the material for the seal

The selection of a suitable material for the seal is largely determined by the environment in which it is working, particularly the fluids with which it is in contact. Other important factors are wear resistance, temperature resistance, dimensional stability and cost.

A selection of seal materials with typical properties is shown in the following table.

Property Nitrile rubber Polyurethane Flouropolymer

Compatibility with: mineral oil Excellent Fair Excellent

chemicals Fair Poor Excellent

Temperature^oC maximum 100 200 200

Minimum -40 -70 -25

Wear resistance Excellent Excellent Good

Dimensional stability Fair Fair Good

Resistance to extrusion Poor Fair Good

Cost index 1 4 10

Property		Nitrile rubber	Polyurethane	Flouropolymer
Compatibility with:	mineral oil	Excellent	Fair	Excellent
	chemicals	Fair	Poor	Excellent
Temperature^oC	maximum	100	200	200
	Minimum	-40	-70	-25
Wear resistance		Excellent	Excellent	Good
Dimensional stability		Fair	Fair	Good
Resistance to extrusion		Poor	Fair	Good
Cost index		1	4	10