When we talk about the chemical processing industry, this can cover anything from petrochemicals to polymers or pharmaceuticals. The reason they are all grouped into the chemical industry is that the processes used in each case require raw materials that are toxic, or may produce products or by-products which are themselves toxic. This means that any control valve used within the process must be able to withstand the chemicals being used, and, particularly when you consider the pharmaceutical industry, must not in any way change or detrimentally effect the end product, more often than not a drug for a patient. These chemical resistant valves must also be able to stand the very stringent cleaning and sanitisation processes used within such processing plants, including clean in place (CIP) and steam in place (SIP).
What Kinds of Chemical Resistant Valves are Most Commonly Used in Pharmaceutical Applications?
A control valve is a power-operated valve used to modify the fluid flow rate in a process system by an external controller. There are two basic types of control valves: rotary motion valves which have ball valve, butterfly or plug type valve closures, and linear motion valves which have a globe valve or diaphragm type closure.
The most common control valves used in pharmaceutical and chemical processing are diaphragm valves, globe valves and ball valves. Butterfly valves are popular for larger scale chemical processing.
Here are some of these chemical resistant valves in more detail:
- Ball valves – these use a hollow, pivoting ball within an aperture to control flow. Usually, a quarter-turn will result in a full flow, so ball valves are often known as quarter-turn valves. The ball valve’s switch mechanism is usually aligned with the aperture of the ball, so that it is easy and quick to establish the status of the valve (open or closed)
- Globe valves – these are designed to stop, start and regulate a flow. Consisting of a stationary seat which a moveable plug is designed to manoeuvre into using a valve stem, a globe valve can be set up to either close against the flow or in the same direction as the flow. With globe valves, it is possible to adjust the flow rate in accordance with the opening size
- Solenoid valves – these use electricity for valve control, allowing the linear motion generated by the solenoid to control a piston or actuator within a valve. This electronic flow control of liquids or gases provided by solenoid valves is often used for control valves in chemical processing because they provide automated actuation, fast response times and are ideal for fail safe systems
Source: Environmental XPRT