O-Ring Sizes Catalogue

O-Rings and Seals for Potable Water Use

Gmors develops and manufactures 20 compounds for potable water applications that conforms to National Sanitation Foundation NSF 61 and WRAS Standards.

The NSF Standards 61 is the regulatory authority which stipulates requirements of potable water system components as well as water treatment chemicals that comes into contact with drinking water in the process of treatment, distribution and dispensing. The requirements ensure that toxic chemicals and substances are not introduced into potable water systems that can cause adverse health effects.

Water Regulations Advisory Scheme (WRAS) is the United Kingdom's approval scheme for the water industry that regulates the use of materials and components in water supply systems to ensure non-contamination.

Background

The use of chlorine as a bacterial disinfectant in the potable water industry has been ongoing for many years. While effective against bacteria, chlorine use in potable water systems produces disinfection-by-products (DBP), and at higher levels, DBP has been proven to be carcinogenic. Limits have been set on the level of DBP to be found in drinking water systems by the Environmental Protection Agency (EPA).

Water treatment, processing and distribution plants and municipalities react to the new limitations set by the EPA by replacing chlorine with chloramine. Chloramine resolves health concerns because it creates less by-products. However, chloramine has an adverse effect on elastomers resulting in a higher frequency of seals and gaskets failure. Chloramine attack gives rise to extensive swelling and loss of resilience in elastomers, with sulfur-cured elastomers having a higher incidence of failure than peroxide-cured alternatives. Chloramine are tested and determined to have a more deleterious effect on some elastomers.

The Solution: Chloramine-Resistant Elastomers

Gmors offers chloramine-resistant sealing options based on a choice of elastomeric formulations.

EPDM (Ethylene propylene diene monomer) is widely used in potable water systems because of its good resistance to water containing chlorine. However, additional resistance testing is required for water containing higher levels of chlorine or chloramine. Chloramine-resistant EPDM formulations contain lower content of carbon black and a higher content of saturated ethylene.

Silicone (VMQ) is superior to all other elastomers when it comes to chloramine resistance. However, compared to other elastomers, silicone has drawbacks in mechanical properties because of its lesser resistance to abrasion, tensile strength and tear strength. While silicone rubber (VMQ) is considered the ideal solution in terms of resistance to chloramine attack, cost factors and its comparatively reduced mechanical properties are to be taken into account.

Contact us today and let us offer our recommendation for a cholramine-resistant sealing solution that is cost effective.

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