A diaphragm valve , also called a membrane valve, is a specified valve which consists of a valve body with two or more ports, a diaphragm and a "saddle" or a seat to close the valve.

The invention of the diaphragm valve dates back to the ancient Roman and Greek times. It is originally carried out to control the water and temperature of the hot baths. At that moment, the crude leather diaphragm is a kind of primitive but effective control valves which was manually closed over a weir. But actually, the first modern valve was invented by Saunders, being named after Saunders in the early 1900s. It is developed with the implication of the idea of cutting the costly power losses due to faulty, leaking seats and stuffing boxes of the valves used to supply air and water in the underground mines. As times goes by, a variety of advanced plastic and elastomeric materials were used in the internal construction of the valve. Thus, it was becoming applicable for much more fields. Similarly, the new valves with high reliability and quality came into being and were accepted by more manufactures. During the process, some famous manufacturing companies have advanced with a moderate pace and are moving toward a bright future.

Nowadays, it is well know that the diaphragm valve is available for more fields for the advantages that it can be either manually or automated controlled by various types of actuators. It is originally used for non-hygienic applications for some limitations. And it has expanded its application for bio-pharmaceutical industry by using compliant materials that can withstand sanitizing and sterilizing methods. And generally speaking, the overall the diaphragm valve is classified into two main categories. The one seals over a "weir" and the other seals over a seat. The major different is that the previous kind has its two ports in line with each other on the opposite sides of the valve and the later one has the in/out ports located at a 90 degree angle from one another.

At last, taking a look at its proper materials is necessary. For the valve body, brass, steel and plastic is appreciated. And cast iron, ductile iron, carbon steel and stainless steel are common steel types. What else, for the body lining materials, it is generally determined by the temperature, pressure and chemical resistance. For example, the NR/Hard Rubber/Ebonite, BR/Soft rubber and EPDM are common rubber lined types.Furthermore, SI/Silicone rubber and such unlined or rubber lined type is proper to make the diaphragm.

With the development of the, it is believed that the development of the modern industry continues to be a much brighter future