Scratching my head on EPDM vs VITON with SANTOPRENE Diaphragms


Active member
As I'm delving into the World of 12V pumps for various applications,..I am running into a a couple of questions I keep asking myself. Most of these pumps seem to use VITON or EPDM valves with Santoprene diaphragms? EPDM seems to have a decent rating for a wide range of cleaners that are used in our work. Seems to rate on average good. VITON is the preferred and superior product from what I understand,..but here's the question I have for those who may have experience with tear downs of these pumps.

From what I gather the valves and the diaphragm are in direct contact with whatever liquid is being pumped? EPDM and Santoprene are a similar material. Even if Viton is superior, but the diaphragm is Santoprene,..wouldn't the Santoprene give up first anyhow thus compromising the pumps performance? Even if the Viton is still in perfect condition what's the point if the "Weak Link" has broken?

I guess I'm wondering why having Viton is so important in a pump with Santoprene diaphragms? Seems EPDM and Santoprene would have about the same life,..making Viton valves a moot point.

If anyone knows why the valve material is more important than the diaphragm material please let me know,..I am just assuming they each see the same exposure to the chemical,..BUT,..I really don't know and want to learn.