The water supply pipeline system generally applies EPDM rubber seal ring, which has been gradually applied in China. Compared with other ordinary rubber seals, it has good anti-aging properties.
According to relevant test reports, ethylene propylene diene monomer (EPDM) rubber is naturally aged for 23 years with a section compression rate of 30%, and the compression set is less than 10%; For other ordinary rubber, when the section compression rate is 30%, the compression permanent deformation will exceed 10% after natural aging for several years. In the medium containing 50 ppm ozone, the cracking time of ethylene propylene diene monomer (EPDM) rubber is more than 150 hours when static tension is 30%; Butyl rubber cracked in only a few hours. In the medium containing 100 ppm ozone, EPDM rubber still does not crack after 2430 hours; The butyl rubber had a large crack in only 534 hours, while the neoprene cracked in 46 hours.
The different molecular structure characteristics of ethylene propylene diene monomer (EPDM) largely determine the performance differences of rubber sealing rings: at present, the molecular structure of common rubber such as styrene butadiene rubber (SBR) and natural rubber (NR) widely used contains a large number of C-C unsaturated double bonds, which are very easy to react with active materials in air or medium (such as ozone, oxygen, metal ions, mold, etc.), Cause rubber molecular chain fracture, crosslinking and other aging, so that the rubber loses elasticity and leads to seal failure; The molecular structure of ethylene propylene diene monomer (EPDM) is mainly composed of C-H bond. Due to its lack of polarity, low unsaturation, high chemical stability and excellent chemical resistance, it is suitable for various polar chemicals, such as alcohol, acid (acetic acid, hydrochloric acid, etc.), strong alkali (sodium hydroxide), oxidant (hydrogen peroxide, hypochlorous acid, sodium perbromate), detergent, animal and vegetable oil Ketones and some esters have greater resistance to long time exposure. Their properties (especially anti-aging properties) are much better than those of SBR and NR.
We produced EPDM rubber rings with steel rings inside, it is suitable for our Rieber belling machines, when we finished the socketing, the rubber rings are set inside and can not remove. The sealing is greatly improved and mostly used for water supper. Now diameter is from 50mm to 1200mm, and we can also produce as customer’s requirements.