The features of Diaphragm Valve makes it the most suitable & preferred valve for aseptic and sterile operations. The Diaphragm valve has outstanding self draining characteristics. The diaphragm of the valve is the key performance component providing leak tight shutoff between upstream and downstream. The Diaphragm also isolates the top works or actuating parts from the process media. The operating mechanism of a diaphragm valve is not exposed to the media within the pipeline.
The picture explains the section view of the Diaphragm vlave.
The materials commonly used in bioprocess for the diaphragm is EPDM (Ethylene Propylene Diene Monomer)
- Good mechanical properties.
- Resistant to aging, ozone, oxygen, and ultraviolet radiation.
- Good resistance to steam and CIP fluids.
(Poly Tetra Fluoro Ethylene) is preferred during very high temperatures. Normally PTFE diaphragms are two piece construction. The working surface is PTFE and it is backed with a rubber or EPDM.
Key elements in diaphragm selection:
Diaphragm life depends upon:
- Media compatibility
- Temperature of operation
- Level of extractables
- Resistance to compression
- Regulatory conformance
Other material can be used depending upon the requirements:-
- The nature of the material handled
- Temperature & Pressure
- Frequency of operation
Butyl, Buna - N, Nitrile, Neoprene, Silicon, Viton