Diaphragm valve

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 is constructed from either plastic or steel. Steel valves can be forged or cast; generally forged valves hold higher quality and cast valves come at a lower cost.

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. When more than three ports are included, they generally require more than one diaphragm; however, special dual actuators can handle four ports with one membrane.

Originally, the diaphragm valve was developed for use in non-hygienic industries. Later on the design was adapted for use in the bio-pharmaceutical industry by using compliant materials that can withstand sanitizing/sterilizing methods. Sterilization, easy cleaning (CIP) and drainability are the main reasons why this type of valve is almost exclusively used in process application within the pharmaceutical industry today.

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.

Materials used to construct diaphagm valves

• ABS (Acrylonitrile butadiene styrene)
• PVC-U (Polyvinyl chloride, unplasticized) also known as PVCu or uPVC
• PVC-C (Polyvinyl chloride, post chlorinated) also known as PVCc or cPVC
• PP (Polypropylene)
• PE (Polyethylene) also known as LDPE, MDPE and HDPE (see note)
• PVDF (Polyvinylidene fluoride)
• Stainless Steel e.g. AISI 316L or equivalent

See also

Plastic Pressure Pipe Systems

Diaphragm valve manufacturers

• Aquasyn
• Bürkert
• Gemü
• George Fischer
• ITT
• Novaseptic
• Praher
• Robolux
• Roplan
• Saint-Gobain
• Saunders

External links

• Bürkert A manufacturer's website

• Gemü A manufacturer's website offering free product data sheets

• Georg Fischer A manufacturer's website offering free product data sheets

• ITT A manufacturer's website offering free pdf downloads of product data sheets

• Novaseptic A manufacturers website offering free pdf downloads of product data sheets

• Praher Valves A manufacturers website offering free pdf downloads of product data sheets

• Pipestock - A commercial site offering tables, specifications and showing pictures of product

• Roplan/Sterivalve - A manufacturer's website

• Saunders - A manufacturer's website