Special Service Valves
There Are Two Special Valves:
• Butterfly Valves
• Diaphragm Valves
Butterfly Valve
Butterfly Valves are used in large ducts transporting air or gas, in steam service, and in large water pipes.
Butterfly valves are used for straight, start-stop flow. A thin disc in the body of the valve provides the on-off control,
This type of valve offers little resistance to flow and has a low pressure drop through its seat.
Because of its design, the butterfly valves is not pressure-tight.
A valve operator or manual gear reducer is often necessary to open or
close these valves.
Diaphragm Valves
Diaphragm Valves are used for handling corrosive or toxic fluids. A flexible diaphragm of non-corrosive material separates the process fluid from the valve’s working parts.
The valve stem presses the diaphragm against the valve seat to prevent fluid flow. The diaphragm valve is good for throttling and controlling flow . When it is tightly closed, the diaphragm stops all fluid flow.
These valves are used in service for chemicals, abrasive or corrosive materials, and vacuum processes.