Butterfly valves consist of a seal around a pipe wall, a round disc or plate, and a control lever. The valve’s disc rotates ninety degrees at the turn of the lever. When the disc is parallel to the flow of water, the valve is in open position and lets all gases or liquids pass; when the handle is turned, the disc rotates around to a position parallel to the flow of water. It fits snugly into the seal and blocks all flow through the pipe.
Butterfly valve manufacturers have a number of options for material when producing butterfly valves. Stainless steel butterfly valves are the most common, because they are naturally corrosion resistant, efficient, highly sanitary and require less maintenance then other materials. These valves are often found in water distribution pipes and chemical service vehicles.
Cast iron butterfly valves are another material based style that is known for its strength and durability, although even when it is the main material for a valve, stainless steel or aluminum is used for the gasket since that needs a light and flexible metal. Plastic butterfly valves cost less to produce but are not as common as the metal valves, mostly because of the corrosion factor that is a common problem in piping.
Butterfly valves have advantages and disadvantages in comparison to other types of flow devices. They are efficient at blocking flow and do not result in leakage, but they are difficult to thoroughly clean and are therefore not appropriate for applications that require sterility, such as in the food or medical industry; although sterile metals, such as stainless steel, are occasionally used. Majority of the industrial companies that employ butterfly valves are manufacturing companies, chemical and water based companies and anything that has to do with pipes.
Depending on the size and shape of the pipe where the butterfly valve will be placed, the manufacturers can alter the butterfly valve design. If the environment is going to be high or low pressure, specific types of butterfly valves will be used, as is the case with different types of piping connections.
The winged and raised edges of flanged butterfly valves allow them to be attached between pipes, creating a leak resistant seal, while there are triple offset valves that seal the pipe in three different places, ensuring no leak will occur. Whatever the piping need, there is a butterfly valve to meet it.