The handle rod of the handle butterfly valve directly drives the valve plate, which switches quickly but is laborious. The worm gear butterfly valve is driven by the worm gear, and the switch is slow but labor-saving. Therefore, the handle butterfly valve is particularly laborious when the pressure in the pipe is high.
The butterfly valve commonly used in engineering is generally the worm gear butterfly valve, because in addition to saving labor, its seal is better than the handle butterfly valve, especially in the high switching frequency environment, the service life is longer than the handle butterfly valve.
Commonly used butterfly valves include wafer butterfly valves and flange butterfly valves. Wafer type butterfly valve uses double-head bolts to connect the valve between two pipeline flanges; flange type butterfly valve has flanges on the valve, and bolts the two ends of the valve flange to the pipeline flange.
The butterfly valve has two sealing types: elastic seal and metal seal.
Elastic sealing valve, the sealing ring can be inlaid on the valve body or attached to the periphery of the butterfly plate.
Valves with metal seals generally have a longer life than valves with elastic seals, but it is difficult to achieve complete sealing. Metal seals can adapt to higher operating temperatures, while elastic seals have the defect of being limited by temperature.