Pressure Seals, Inc on Facebook

Don't see what you are looking for? Many other products available. Please use our quickquote form to inquire.

Quad Rings Overview
Quad Ring Seals
Quad P.E. Plus Plastic Extrusion Seals
Quad Brand O-Rings
Standard Size Guide for Quad Ring & Quad Brand Seals

The simple o-ring is usually the designer's first choice when a sealing application is encountered. Properly engineered to the application, an o-ring will provide long-term performance in a variety of seal applications. O-rings are well suited for use as static and reciprocal seals; they are also appropriate as rotary and oscillating seals in low speed and low pressure applications.


The o-ring is a good general purpose seal in both air and gas systems, as well as in hydraulic applications. Air and gas system designs must include adequate lubrication of the o-ring in order to prevent damage to the sealing surface.

The popular o-ring cross-section is configured in a variety of shapes as a stand alone seal, or incorporated into other rubber sealing components such as gaskets and diaphragms. O-ring cross-sections are molded or bonded to metal or plastic parts such as valve stems, quick-disconnect poppets and spool valve cylinders.
O-Ring Groove Design
When specifying an o-ring, choose the largest cross-section possible. The greater the cross-section, the more effective the seal and the longer the service life. A small cross-section does not provide the surface contact area required for an effective seal, especially in dynamic sealing situations.

Backup Washers
A backup washer should generally be used at pressures greater than 1500 PSI (103.4 Bar) to prevent seal extrusion. Groove dimensions also need to be increased to accommodate the added thickness of the washer.
Groove Design for O-Rings Without Backup Washers
All surfaces and corners must be free of tool marks, nicks or scratches.
  1. Refer to Clearance Chartto determine proper diametrical clearance based on the pressure encountered and the hardness of the rubber compound.
  2. Bore Diameter "A" (at upper limit), minus two times Groove Depth "C", equals Piston Groove Diameter "B."
    A - (2 x C) = B
    Rod Diameter "H" (at lower limit), plus two times Groove Depth "C", equals Groove Diameter "L."
    H + (2 x C) = L
  3. For backup washers, increase groove length "D" by thickness of washers used. Use minimum radius in groove.

NOTE: See Non-Rotary section for additional groove design information.

Recommended Starting Dimensions for Typical O-Ring Applications
Seal Number Actual Cross-
Minimum C/S Squeeze Maximum "C" for Minimum
C/S Squeeze
Groove "D"
Axial Dimen.
-.000/+.005 in.
  (in) (mm) Dynamic Static1
Dynamic Static2
(in) (mm)
8004-8050 .070 ± .003 1.780 ± .076 .010 .015 .254 .381 .055/.057 .050/.052 1.397/1.448 1.270/1.320 .094 2.387
8102-8178 .103 ± .003 2.616 ± .076 .010 .017 .254 .432 .088/.090 .081/.083 2.235/2.286 2.057/2.108 .141 3.581
8201-8284 .139 ± .004 3.530 ± .101 .012 .022 .305 .559 .121/.123 .111/.113 3.073/3.124 2.819/2.870 .188 4.775
8309-8395 .210 ± .005 5.334 ± .127 .017 .032 .432 .813 .186/.188 .171/.173 4.724/4.775 4.343/4.394 .281 7.137
8425-8475 .275 ± .006 6.985 ± .152 .029 .049 .736 1.244 .238/.240 .218/.220 6.045/6.096 5.537/5.588 .375 9.525

See chart for Quad-Ring seal groove dimensions.

  1. In certain cases (e.g., very close control of concentricities, absence of temperature extremes, etc.) tests may indicate that the squeeze can be reduced (and seal life prolonged) by increasing the groove diameter.
  2. For certain shaft sizes, use of the standard size Series 4 seal may require more peripheral squeeze than is desired for the application. In such cases, use of a special size Series 4 seal is recommended. Contact our Fluid Delivery Team for details.

Information Provided by Minnesota Rubber/Quadion Corporation, copyright 2002
Product names are Registered trademarks of Minnesota Rubber, A Quadion Company.