Valve is a device that regulates, controls or directs the flow of a fluid by opening, closing, or partially obstructing fluid flow. Sound bit complicated? Ok, let me further simplified this. A valve is a mechanical device that controls the flow and pressure of fluid within a system or Process. So basically, it controls flow & pressure.
In piping following types of valves are used depending on the requirements.
The cost of Valve in the piping system is up to 20 to 30% of the overall piping cost. And the cost of a given type and size of the valve can vary 100%. It means that if you choose ball valve over butterfly valve for the same function. It can cost you more. So, the selection of valves is essential to the economics, as well as operation, of the process plants. Some different types of valves are:
Pressure Relief Valve