Diaphragm valve
From Wikipedia, the free encyclopedia
Diaphragm valves (or membrane valves) consists of a valve body with two or more ports, a diaphragm, and a "saddle" or seat upon which the diaphragm closes the valve. The valve body is commonly constructed from high grades of stainless steel, e.g. AISI 316L, inert polymers e.g. PVDF or higher alloys e.g. Ti, Hastelloy. Common materials for the diaphragm seal include EPDM, PTFE, Aflas, Ultraz and other fluoroelastomers which can be sanitized with superheated water or sterilized with steam.
Originally, the diaphragm valve was developed for use in none hygienic industries. Later on the design was adapted for use in the Bio-Pharmaceutical industry by using FDA compliant materials that can withstand Sanitizing/sterilizing methods. Additionally, the valve design was modified to satisfy low product hold up and drainability requirements of cGMP.
There are two main categories of diaphragm valves, one type seals over a "saddle" and the other seals over a seat. The main difference is that a saddle-type valve has its two ports in line with each other on the opposite sides of the valve. Whereas the seat-type has the in/out ports located at a 90 degree angle from one another. The saddle type is the most common in process applications and the seat-type is commonly used as a tank bottom valve. Both types come with three ports and even more; however, when more than three ports are included, they require more than one diaphragm.
Diaphrgam valves can be manual or automated. Their application is generally as shut-off valves in process systems within the food and beverage, pharmaceutical and biotech industries. The older generation of these valves is not suited for regulating/controlling process flows, however newer developments in this area have successfully tackled this problem.
In addition to the well known, two way shut off diaphragm valve, there are many other forms of the diaphragm valve including three way zero deadleg valve, GMP valve, Sterile access port, point of use zero deadleg, valbow, tank bottom valve, just to name a few.
Companies that manufacture diaphragm valves include:
