Seals

2.1 Specify the environment

The material for the seal is largely determined by the environment in which it is working, particularly the fluids with which it is in contact and so the following factors should be specified:

type of fluids being separated;
ambient pressure;
abrasion and wear resistance;
dimensional stability required;
pollution;
humidity;
ambient temperature;
vibration.

A guide to the limiting values of those factors that can be quantified is shown in the following table.

Seal type Gasket Gland Lip Chevron 'O' ring Face Non-contact

Factor

PRESSURE (bar) Unbacked - 1.0 0.5 6.0 - 100 -

Backed - - 6 300 100 - -

SPEED (m/s) - 13* 15 1.6 0.2 15 High

LEAKAGE v.low low low v.low v.low low high

SURFACE
FINISH(mu.m) 0.4 0.4 1.0 0.2 - 0.6 0.8 0.8 -

TEMPERATURE (^oC) 200 200 150 500$ 120 600$ -

* For recprocating motion a limit of 0.75 m/s.

$ Actual temperature limit determined by the material chosen.

	Seal type	Gasket	Gland	Lip	Chevron	'O' ring	Face	Non-contact
Factor
PRESSURE (bar)	Unbacked	-	1.0	0.5	6.0	-	100	-
	Backed	-	-	6	300	100	-	-
SPEED (m/s)		-	13*	15	1.6	0.2	15	High
LEAKAGE		v.low	low	low	v.low	v.low	low	high
SURFACE FINISH(mu.m)		0.4	0.4	1.0	0.2 - 0.6	0.8	0.8	-
TEMPERATURE (^oC)		200	200	150	500$	120	600$	-