What is a Valve?
Valve is a device which is used to regulate the flow in a pipe line. It may be mechanical thing but the function is very much required for Chemical engineering operations. Based on the requirement, allowed pressure drop, flow rate we can employ different kind of valves. Valves often change the flow pattern in pipe lines. This may be due to the obstruction or restriction offered by the valve body. Here boundary layer separation may occur, which leads to form friction. In order to calculate form friction pertaining to that particular valve we have L/D ratios and K values.
Types of valves
Types of valves
Here are the some of most common valves using in Chemical industries.
- Globe valves offer better control of flow but at the expense of large pressure drop. Most of the control valves are globe valves.
- In Gate valves a Gate facilitate the flow of fluid. It will slide from complete open to close position.In gate valves the sliding stem can be movable or fixed stationary.
- Ball valves contain a ball as a flow regulating element. The ball contains a provision to allow the flow. One quarter (1/4) turn of the valve handle can regulate the flow from minimum to maximum.
- Function of plug valve is similar to Ball valve but the regulating element will be different.
Check valves( Non Returning Valves)
- Check valves or non returning valves allow flow only in one direction. Opposite direction flow doesn't happen here. This is particularly useful in reactor inlets, where exothermic reactions might happen in pipe lines.
- Butterfly valves contain a disk which can rotate from 0 to 90 degrees for complete close to open state. This valve can be used as a control valve in water service.
- Similar to Globe valve , a diaphragm valve contains a plate like arrangement which functions as a stem in Globe valve.
- Control valves are a special class of valves which are highly useful in controlling the flow of a fluid in pipe lines from a control room. Control valve contains a stem which can be varied by giving the set points from the distributed control system(DCS). Control valve design also important thing in process industries.
Still a lot of valves are out there , each of which has its own feature. To name a few Solenoid valves, needle valves etc.,
Useful Link : http://www.valvedirectory.com/valve_list_a-z.html