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.

Return to Products >

Downloads

BACK-UP RINGS WJ21 >
BS ORING SIZES WJ21 >
O RING CHEMICAL COMPATABILITY WJ21 >
O RING MATERIALS WJ21 >

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.

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Disclaimer
Please note, failure to select the correct materials or products we supply (“the Products”) may result in damage to plant, equipment or property. In some instances, it may cause death or personal injury. We are not designers and do not give advice about design related matters concerning the Products. We can help and assist with the technical specifications for the Products. In specific applications, particularly where critical conditions exist, we will try to assist you within the limitations of the services that we offer. All information supplied by us is intended as technical co-operation outlining the specifications of the different Products which we supply. To the extent permitted in law, no warranty is given in respect of any information supplied by us. The customer must satisfy themselves as to the suitability of the Products for their intended application and use. The correct fitting of Products is the responsibility of the customer. Your statutory rights remain unaffected. Save in respect of death, personal injury or fraud, our entire liability to you, however arising from the supply of Products shall be limited to the £10M indemnity amount provided by our insurers.