Drinking Water O-Ring Catalogue

Ge Mao Rubber Industrial Co., Ltd.
Tel: +886-4-7810288
Fax: +886-4-7810289
No. 15, Kung Yeh East 4th Rd., Lukang, Chang Hua 505, Taiwan, R.O.C.
WRAS, NSF Standards 61 O-Rings
Potable Water O-Rings

O-Rings and Seals for Drinking Water Applications

GMORS offers o-rings and seals for drinking water applications with compliance to WRAS Standards and NSF 61 (National Sanitation Foundation). Our R&D team of engineers formulate at least 20 compounds suitable for drinking water applications complying with the above standards.

NSF Standards 61: The guidelines which regulate the requirements of system components and chemicals that is exposed to drinking water during treatment is NSF Standards 61. The standards ensure that chemicals and substances that are toxic do not end up in drinking water systems, causing adverse effects on health.

WRAS: Water Regulations Advisory Scheme

The approval scheme in the United Kingdom that regulates the use of components and materials to ensure non-contamination of water supply system sis the WRAS.


For many years, the potable water industry makes use of chlorine as a disinfectant against bacteria. However, the use of chlorine in drinking water systems gives rise to DBP (disinfectant-by-products) which at higher concentration, has been shown to be carcinogenic. The EPA (Environment Protection Agency) set limits on the level of disinfectant-by-product to be found in potable drinking systems.

The new regulatory limits set by the Environment Protection Agency resulted in chloramine been used as a substitute for chlorine as municipalities, water processing and distribution facilities find ways to reduce disinfectant-by-products caused by chlorine usage. Although chloramine produces less DBP, it has a damaging effect on elastomeric seals, giving rise to a loss of resilience and excessive swelling. A higher incidence of failure of elastomeric seals and gaskets occurs with the use of chloramine as disinfectant, with sulfur-cured elastomers performing less satisfactory than peroxide-cured elastomers. It has been tested and shown that chloramine has a more damaging effect on certain elastomers.

GMORS Solution: Chloramine-Resistant Elastomers

Sealing systems formulated to be chloramine resistant are offered by GMORS, with a selection of elastomeric compounds available.

Ethylene propylene diene monomer (EPDM) has excellent resistance to chlorine found in drinking water, and is extensively used in drinking water systems. At higher concentrations of chlorine or chloramine however, additional resistance testing is necessary. Formulation-resistant formulations of EPDM has a higher level of saturated ethylene and a lower level of carbon black.

Silicone (VMQ) performs better against chloramine attack as compared to other elastomers. However, silicone has a lower abrasion resistance and lower tensile and tear strength. The lesser mechanical properties of silicone has to be taken into account while considering the benefits of its resistance to chloramine attack.

Contact us for a cost efficient recommendation of a chloramine-resistant sealing system.

Copyright © 2017 Ge Mao Rubber Industrial Co., Ltd.