Manual valve types and usage Butterfly Valves
Butterfly valves control the flow of gas or liquid by means of a disk, which turns on a diametrical axis inside a pipe or by two semicircular plates hinged on a common spindle, which permits flow in only one direction.
Complies with ASME face to face dimensions and pressure ratings, hence enabling ease in retrofitting.
-Provides a bubble tight, bi-directional shut off.
Available in plastic and rubber linings and solid metal bodies and discs. For body, materials used are Cast iron, ductile iron, aluminum, carbon steel, stainless steel
Inflatable seated butterfly valve, double offset butterfly valve and triple offset butterfly valve.
Adv:
- Relatively high coefficent of flow
- Economical choice for large line sizes (i.e 8” and above)
- Availability in chemically resistant materials
- High recovery valve (low pressure drop, as only a disc stands in the way of the flow)
- Less wear compared to globe valves
Dis-adv:
- Lack of cleanliness and inability to handle slurry applications.
- Not bubble tight
- Cavities and leak paths around disc stem could trap fluids and slurries resulting in unwanted contimination
