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.
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)|
|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)|
|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)|
|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|
|Permeability To Gases||Poor||Low||Low||Low||Low||Low||Low||Low||Very Low||Low|
|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
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.