Rubber Mouldings

William Johnston & Company Limited- is recognised for technical ability, customer service and quality accreditation and supply custom rubber mouldings, thermoplastics, rubber injection mouldings, compression and transfer rubber mouldings with recognised approvals for specific industries.

We offer a wide range of rubber compounds meeting many industrial specifications including British and European standards, Automotive, MOD, WRAS and FDA requirements

Elastomer Types Overview
There is a wide variety of polymers available, each with their own unique properties. We recommend that our Technical Department is involved at the earliest opportunity to optimise all the various aspects of the product or service requirements and together find the most effective compound and efficient solution that will result in a technically accurate, cost effective and high quality end product for you.

WRAS approved EPDM compounds
Are used for cold and hot potable water use to the requirements of the UK, German and French water industries.

Nitrile compounds
Are approved to EN 549, EN 682 for gas applications and by WRAS for cold potable water use.

Fluorocarbon (FKM) and Hydrogenated Nitrile (HNBR) compounds
Are approved for use in Well Head safety equipment.

William Johnston & Company Limited are able to offer compounds that conform to British Standards, ISO, Def Stan (Defence Standard), DTD specifications, ASTM, AMS, WRC, WRAS and SAE. Below is an overview of some of the most common elastomers which we supply but please contact us for more specific information and assistance.

	Natural Rubber	SBR	EPDM	Neoprene (CR)	*Hypalon (CSM)**	Nitrile (NBR)	Acrylic (ACM)	Silicone (Si)	*Viton(FPM)**	Fluro- silicone (FSi)
Basic Properties
Cost Factor	1	1	2	2	3	2	4	6	15	40
Hardness Range (Shore A)	30 - 90°	40 - 95°	30 - 85°	30 - 90°	40 - 85°	40 - 100°	50 - 85°	40 - 80°	50 - 95°	40 - 80°
Colours	Full Range	Full Range	Limited	Full Range	Limited	Limited	Black	Limited	Limited	Limited
Temperature Tolerances (degrees Celsius)
Maximum Continuous	75°	85°	130°	95°	130°	100°	150°	205°	205°	180°
Maximum Intermittent	105°	115°	150°	125°	160°	130°	180°	300°	300°	200°
Minimum Temperature	-60°	-55°	-50°	-40°	-25°	-20°	-20°	-60°	-20°	-60°
Environmental Tolerances
Oxidation	Fair	Fair	Excellent	Very Good	Excellent	Good	Excellent	Excellent	Excellent	Excellent
Ozone & Weathering	Poor	Poor	Excellent	Very Good	Excellent	Fair	Excellent	Excellent	Excellent	Excellent
Oil Resistance (degrees celsius)
ASTM Oil No. 1 @ 20°	Poor	Poor	Fair	Excellent	Excellent	Excellent		Excellent	Excellent	Excellent
ASTM Oil No. 1 @ 100°	Poor	Poor	Poor	Good	Good	Good	Excellent	Good	Excellent	Excellent
ASTM Oil No. 3 @ 20°	Poor	Poor	Poor	Good	Excellent	Excellent		Good	Excellent	Excellent
ASTM Oil No. 3 @ 100°	Poor	Poor	Poor	Fair	Fair	Good	Good	Fair	Excellent	Excellent
Fuel Resistance (degrees celsius)
ASTM Fuel B @ 40°	Poor	Poor	Poor	Poor	Poor	Fair	Poor	Poor	Excellent	Fair
*Solvent Resistance (@ 20° celsius)*
Alcohol	Good	Good	Good	Good	Good	Good	Good	Good	Good	Good
Acetone	Fair	Fair	Good	Fair	Fair	Poor	Poor	Fair	Unsuitable	Unsuitable
Benzene	Poor	Poor	Poor	Poor	Poor	Poor	Poor	Poor	Good	Good
Chemical Resistance
Acids	Fair	Fair	Good	Good	Very Good	Good	Poor	Fair	Excellent	Good
Bases	Good	Good	Good	Fair	Good	Fair	Poor	Fair	Good	Fair
Physical Properties
Physical Strength	Excellent	Good	Good	Good	Good	Good	Good	Poor	Good	Poor
Compression Set	Good	Good	Good	Fair	Fair	Good	Good	Good	Good	Good
Tear & Abrasion Resistance	Excellent	Good	Good	Good	Good	Good	Good	Poor	Good	Poor
Resilience	Excellent	Good	Very Good	Very Good	Fair	Good	Poor	Good	Fair	Fair
Resistance
Permeability To Gases	Poor	Low	Low	Low	Low	Low	Low	Low	Very Low	Low
Electrical Strength	Excellent	Excellent	Excellent	Good	Good	Poor	Fair	Excellent	Good	Excellent
Flame Resistance	Poor	Poor	Poor	Self - Extinguish	Good	Poor	Poor	Good	Self - Extinguish	Self - Extinguish
Water Resistance	Very Good	Good	Excellent	Good	Very Good	Good	Poor	Good	Good	Good

*Du Pont Registered Trade Mark | †Bayer Registered Trade Mark

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Downloads

DIN Seals FDA USP WRAS EC 1935_2004 WJ21 >
Flexible Connectors WJ21 >
Oval Door Seals FDA EPDM & NATURAL WJ21 >
RJT Seals FDA USP WRAS EC 1935(2004) WJ21 >
Rubber mouldings to ISO 3302 1995 (BS 3734) materials WJ21 >
Rubber mouoldings to ISO 3302 1995 (BS3734) tolerances WJ21.pdf >
tri clamp fittings and seals WJ21 >
Valve Come WRAS selection and fitting WJ21 >

Contact William Johnston & Company Limited

For more information about our Rubber Mouldings 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.