O-Ring Groove Design

A = Uniform Dash Number
B = Actual Cross Section Dia.
C = Dynamic1
D = Static
E = Dynamic1
+ .000/-.001
F = Static +.000/-.001
G = No Backup Ring
H = One Backup Ring
I = Two Backup Rings
J = 500 PSI
K = 1500 PSI
L = Eccentricity3
(Maximum)
M = Radius (R)
  Diametral Squeeze (Minimun)     Gland Depth F   Groove Width G + .003     Diametral2 Clearance (Max) D    
See A above See B above See C above See D above See E above See F above See G above See H above See I above See J above See K above See L above See M above
-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 .006 .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

Recommendations

1. The following sizes are not normally recommended for dynamic service, although special applications may permit their use:

-001 thru -003       -223 thru -284
-013 thru -050       -350 thru -395
-117 thru -178       -461 thru -475

2. Clearances shown are based on 70 durometer materials. The clearances must be held to an absolute minimum consistent with design requirements for temperature variations and should not exceed the values shown.

3. Total indicator reading between groove and adjacent bearing surface. All surfaces and corners must be free of tool marks and scratches.

Surface Finishes for O-ring Installation
Type Possible Result Comments
Polished (non-porous) Lubrication will be lost resulting in high friction rate and
possible seal failure.
Not recommended
Rough Tearing and abrasion of seal may occur, possible seal failure. Not recommended
Burnished/Mandrel A surface finish exceeding the recommended surface finish range, possible seal failure. Although these methods produce a very accurate diameter, they are not recommended.
Ideal 20-24 RMS (.5-.6 Bar)
20-32 RMS (.5-.81 Bar)
Not to be finer than 16 RMS (.4 Bar)
Recommended

Groove Design for O-ring Installation

O-ring groove dimensions may be calculated as follows:
O-ring groove chart
Rod Seal
Given:
Rod Diameter C
O-ring Cross Section W
Dynamic application
No back-ups required
Example:

= .500”
= 3/32” nominal
Determine:
O-ring size
Gland Depth F
Groove Width G
Rod Gland D
Example:
= AS-568-112 (1/2” ID x 3/32” W nominal dimensions)
= .090 (+.000" -.001") .003
= .144 ± .003”
= C + 2F = .500” + 2x.090”= .680”
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
Piston Groove B

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

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