EPDM Valve Seals - Water service - Chlorine Dioxide

[BRIS]

We have recently changed from water disinfection by chlorine gas to chlorine dioxide. Previously specified seals and gaskets to be manufactured from EPDM. It has been suggested by one manufacturer that EPDM is no longer suitable for use with chlorine dioxide disinfectant and that we should change our specification for seals and gaskets to Flourocarbon (FKM) Rubber.

We need a material that is suitable for use in water service with both chlorine and chlorine dioxide disinfectants.

 

[bljnv]

Please go to this link

http://mykin.com/rubber-chemical-resistance-chart-2

 

[btrueblood]

EPDM is generally resistant to chlorine, hypochlorite (ClO), chlorite (ClO2), chlorate (ClO3) and perchlorate (ClO4), as salts (of potassium, sodium, etc.) in aqueous solutions; there are chloramine disinfectants that can attack some types of EP rubber - but there are also chloramine resistant EPDM formulations.

In general, EPR is suitable for any water-soluble chemistry short of concentrated acids - but that may be what you have if you are bubbling pure chlorine gas or chlorine dioxide gas into water to the point of saturation (the gas phase does attack the EPDM). Fluoro-elastomers vary in formulations, and some can actually be less resistant than EPR in certain situations (hot/boiling water being one, again depending on the formulation of the FKM); fluoroelastomers are good when hydrocarbons (fuels and oils) are present - and some formulations are resistant to the gases listed. I'm sure the manufacturer would love to sell you more expensive seals, and mark them up accordingly...

Another good source for chemical resistance data is the Parker O-ring Handbook, available for free download from their website, or just google for it.