The answer to this question is unique to each application. 
Because of the number of factors that affect diaphragm life, such as diaphragm material, SIP cycle and temperature, CIP cycle, CIP solution, and so on, you can have diaphragm life from a few days to a few years.
For a more in-depth answer email us for a copy of the Asepco Qucikread Vol. 1, Iss. 1 at info@asepco.com.