In many types of processing and production, chemicals are used throughout the process. Complex systems to precisely control the flow of the chemicals throughout pipes in the system are critical. Each of the system elements has to be durable, reliable and resistant to corrosion and degradation by the chemical media.
How Check Valves Work
A chemical check valve, like any check valve, is designed to allow the media to flow only one way through the valve. This is, by definition, a two-port valve, with a relatively simple design. The intake or inlet port will allow the liquid to enter the valve and pass through the valve with no loss of pressure or flow. The media will then exit the valve through the outlet port.
The internal structure in the valve, which can be any type of element from a diaphragm to a ball, is pushed forward with the higher pressure on the inlet side, keeping the valve open and the liquid flowing forward.
Should the pressure or the flow rate drop on the intake side of the valve, the liquid will try to enter the outlet side of the valve under pressure. This will result in the internal structure of the valve, which may be a ball, disc or a diaphragm, to immediately block the inlet valve, preventing any backflow through the system. As soon as the pressure or flow builds up to the required pressure on the inlet side, the process will reverse, and the flow will resume.
Chemical Resistance
A chemical check valve may be designed using different materials. For many applications, the wetted surface of the valve will be made from or coated with PTFE, which offers both extremely low surface friction as well as excellent corrosion resistance.
It will be essential to correctly choose the chemical check valve based on both the flow volume as well as the pressure through the system.