diaphragm valve systems
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.
Originally, the
diaphragm valve was developed for use in non-hygienic applications. Later on the
design was adapted for use in the bio-pharmaceutical industry by using compliant
materials that can withstand sanitizing and sterilizing methods.
There are
two main categories of diaphragm valves: one type seals over a "weir" (saddle)
and the other (sometimes called a "straight-way" valve) 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 more commonly used as a tank
bottom valve but exists also as a process valve. While diaphragm valves usually
come in two-port forms, they can also 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 more ports with one
membrane.
Diaphragm 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 and 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, other types include: three
way zero deadleg valve, sterile access port, block and bleed, valbow and tank
bottom valve just to name a few.
Actuator ,firplace valves.
Diaphragm valves can be controlled by various types of actuators. The most
common diaphragm valves use pneumatic actuators; in this type of Valve, air
pressure is applied through a Schrader valve which raises the diaphragm and
opens the valve. This type of valve is extremely quick and as such is one of the
more common valves used in operations where valve speed is a necessity , temperature control valves.
Hydraulic diaphragm valves also exist for higher pressure and
lower speed operations. Some diaphragm valves are also controlled
manually.
