About butterfly valve Butterfly valves have been around for a long time and have been used more and more widely in various industries since the 1930s when they first came out. Butterfly valves are usually made of cast iron and their name is based on the function of their discs. There are several different types of butterfly valves, but there are always two basic types of butterfly valves — lug and wafer. Butterfly valves are classified as “quarter turn” valves. The valve can be opened or closed by rotating the metal disk of the butterfly valve a quarter turn. When the butterfly valve is fully open, the fluid is allowed…