How to determine O-Ring Size

		Diametral Squeeze (Minimum)		Gland Depth F		Groove Width G +/-.003			Diametral Clearance (Maximum) D
Uniform Dash Number	Actual Cross Section Diameter	Dynamic¹	Static	Dynamic¹ +.000 -.001	Static +.000 -.004	No Backup Ring	One Backup Ring	Two Backup Rings	500 PSI	1500 PSI	Eccentricity (Maximum)	Radius (R)
-.001	.040 +.003	.004	.006	.033	.031	.056	-	-	.005	.0025	.002	.010
-.002	.050 +.003	.005	.008	.042	.039	.070	-	-	.006	.003	.002	.010
-.003	.060 +.003	.009	.009	.051	.048	.084	-	-	.007	.0035	.002	.016
-.004 thru -.050	.070 +.003	.007	.011	.060	.056	.098	.140	.207	.008	.004	.002	.016
-.102 thru -.178	.103 +.003	.010	.015	.090	.085	.144	.173	.240	.009	.004	.002	.016

-.201 thru -.284	.139 +.004	.014	.021	.121	.114	.195	.210	.277	.010	.006	.003	.031
-.309 thru -.395	.210 +.005	.021	.032	.184	.173	.294	.313	.412	.011	.007	.004	.031
-.425 thru -.475	.275 +.006	.028	.042	.241	.227	.385	.410	.540	.012	.008	.005	.047

Note 1. The following sizes are not normally recommended for dynamic service.
-001 thru -003 -013 thru -050 -117 thru -118 -223 thru -284 -350 thru -395 -164 thru -475
Note 2. Clearances shown are based on 70 durometer values.
Note 3. TIR between groove and adjacent bearing surface. Surfaces and corners must be free of tool marks and scratches.

TO CALCULATE O-RING GROOVE DIMENSIONS:

Rod Seal

Given:
Rod Diameter C
O-ring Cross Section W
Dynamic application
No back-ups required

Example
= .500
= 3/32 nominal

Piston Seal

Given:
Cylinder Bore A
O-ring Cross Section W
Static application
No back-ups required

Example
= 1.000
= 1/8 nominal

Determine:
O-ring size

Gland depth F

Groove width G

Rod Gland D

= AS-568-112
(1/2 ID x 3/32 W
nominal dimensions)
= .090 +.000 -.001
(from chart)
= .144 +/-.003
(from chart)
= C + 2F = .500 + 2x.090 = .680

Determine:
O-ring size

Gland depth F

Groove width G

Rod Gland D

= AS-568-210
(1 OD x 1/8 W
nominal dimensions)
= .114 + .000 - .004
(from chart)
= .195 +/-.003
(from chart)
= A - 2F = 1.000 -2x.114 = .772