Lewa Diaphragm pump question

[Meshry]

Reciprocating pump LEWA. diaphragm is sandwich type, means two PTFE diaphragms in between an intermediate fluid.
problem: Diaphragm rapture pressure transmitter alarm!
dismantled the pump, diaphragm found in good condition.
what could be the other reasons.
what is function of the intermediate fluid in the sandwich diaphragms?

thanks

 

[bimr]

If one of the diaphragms ruptures, the pressure switch sensor signals an alarm. Are you sure both diaphragm are in good condition?

All LEWA diaphragm pumps with sandwich diaphragm feature two diaphragms lying on top of each other (made of plastic or metal).

On the discharge stroke the membranes are connected mechanically positive-locking with each other. On the suction stroke they are hydraulically coupled via a fluid or grease film.

In both cases, the space between the two diaphragms is pressureless in normal operation. Only if a diaphragm is damaged does the fluid penetrate into the diaphragm space, leading to an increase in pressure. This increase in pressure in the diaphragm space is used to indicate diaphragm damage.

 

[Meshry]

Dear bimr,
Thanks for your reply.
For diaphragm condition. visually it is good. May be some aging is causing the problem.
What about the diaphragm clamping area? I would say, it may cause the problem also. what do you think?

Thanks