A valve is a device which controls the flow rate, pressure or the path. The controlled fluid can be the liquid, gas, the mixture of gas and liquid or the mixture of strong and liquid. The valve normally is composed of body, seat, bonnet, parts for opening or closing, actuating device, sealing element and so on. The controlling function of the valve depends on the actuating device or the movement of the fluid which drives the sliding, rotating or turning of the parts for opening or closing to modify the region of the flow passage.

Two thousands years ago, the Chinese individuals applied the bamboo trunk and wooden plug into water pipeline. Then later they applied the sluice into the irrigational canal, the plate verify valve into bellows for smelting and so on. With the improvement of smelting process and hydraulic machinery, the plug valve made of brass and lead appeared in Europe. In addition to, with the wide application of boiler, in 1681 the secure valve with lever and heavy bob came into the world. Prior to What is Butterfly Valves? of the Watt steam engine, the plug valve and check valve had been the most important valves. The steam engine leaded the valve into a new field namely mechanical business.

With the increase of the steam flow price and pressure, the plug valve can not satisfy the number of steam admission and exhaustion at all. In order to resolve the dilemma, people today then invented the slide valve. In 1840, the verify valve with threaded stem and the wedge gate valve with threaded stem come to be the excellent breakthrough in the valve field. The two valves did not only meet the requirement for pressure and temperature at that time but also initially satisfy the need to have for flow regulation. Later, for the reason that of the speedy development of power market, oil industry, chemical industry and shipbuilding business, all sorts of higher or middle valves sprang up like mushrooms. What’s extra, right after the Second Globe War, owning to the invention of new supplies such as polymeric material, stainless steel, lubricating material, the old plug valve and butterfly valve get the new application and the ball valve and diaphragm valve develop rapidly.

All in all, step by step the valve manufacturing becomes a single of the important sectors in the mechanical sector. There are a lot of applications for the valve. It is closely connected with our each day life. For instance, the tap utilised for operating water pipe and the minimizing valve utilised for liquefied petroleum gas stove are the valves. What’s more, it is the critical part for diverse mechanical equipments such as gas engine, steam engine, compressor, pump, car, ship or aerocraft.