O-Rings

The table below provides details of some of the more common materials and approvals for our extensive range of O –rings. The list is not comprehensive so please contact us to discuss your requirements or for technical data sheets pertinent to your application.

MATERIAL SHORE HARDNESS FDA
(FOOD & DRUG APPROVED)
PEROXIDE CURED STANDARD LOW TEMP
°C
SPECIAL LOW TEMP TALC FINISH SILICONE OR MOLY OIL FINISH WRAS
(APPROVED PORTABLE WATER USE)
DIFFERENT COLOURS
NITRILE 40-90 -40
SILICONE 30-90 -50 Moly Only
VITON 60-90 -20
EPDM 40-90 -55
NEOPRENE 40-90 -40 Limited
HNBR 70-90 -30 Limited
F-SIL 50-80 -55 Limited
FFKM 75-90 -10 Limited
ACM 60-80 -10 Black Only
AEM 60-70 -40 Black Only
AFLAS 70-80 -9 Black Only
ECO 50-90 -40
BUTYL 60-70 -60 Black Only
NR 50-80 -50
PU 70-90 -40 Limited
SBR 50-80 -25 Black/Blue
XNBR 70-80 -25

PEROXIDE CURE: NOT NORMALLY SUPPLIED IN THIS FORM BUT THOSE MARKED CAN BE

A MINIMUM WORKING LOW TEMPERATURE IS SHOWN ABOVE FOR OUR STANDARD COMPOUNDS WHERE INDICATED A SPECIAL FORMULATION IS AVAILABLE TO WORK AT LOWER TEMPERATURES.

Back-up rings
Back-up rings are plastic or rubber rings used to prevent the O-ring from entering the clearance gap. When high pressures are exerted on the O-ring, its soft rubber material can be forced into the clearance gap causing the O-ring to extrude. The hard back-up ring material will keep the O-ring material from flowing into the gap, which will prevent premature failure.
Please download our back-up rings .pdf for further information

BS STANDARD O RING DIMENSIONS
Also available to download is a list of the British Standard sizes

CHEMICAL COMPATIBILITY
A chemical compatibility reference for both dynamic and static sealing applications is also available for reference.

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Contact William Johnston & Company Limited

For more information about our O-Rings that are available world wide, contact us on +44 (0)141 620 1666, Email us or simply complete our online Enquiry Form.

Failure to select the correct materials or products can result in damage to plant and equipment and personal injury. In specific applications, particularly where critical conditions exist, we suggest you contact us and we will consider with you the most suitable material or product. However, information supplied by William Johnston & Company Limited is intended only as technical co-operation and as a guide to the various uses of different products. No warranty is given in respect of information or recommendations by William Johnston & Company Limited which are only given for guidance and without any guarantee. The customer must satisfy themselves on the suitability of the material or product for the intended purpose. The correct fitting of products is the responsibility of the customer.

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