A valve is a device which controls the flow rate, pressure or the direction. The controlled fluid can be the liquid, gas, the mixture of gas and liquid or the mixture of solid and liquid. The valve usually 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 components for opening or closing to change the area of the flow passage.
Two thousands years ago, the Chinese persons applied the bamboo trunk and wooden plug into water pipeline. Then later they applied the sluice into the irrigational canal, the plate check valve into bellows for smelting and so on. With Click Here of smelting approach and hydraulic machinery, the plug valve made of brass and lead appeared in Europe. Besides, with the wide application of boiler, in 1681 the protected valve with lever and heavy bob came into the world. Ahead of the invention of the Watt steam engine, the plug valve and check valve had been the most significant valves. The steam engine leaded the valve into a new field namely mechanical business.
With the raise of the steam flow price and pressure, the plug valve can not satisfy the quantity of steam admission and exhaustion at all. In order to resolve the challenge, persons then invented the slide valve. In 1840, the check valve with threaded stem and the wedge gate valve with threaded stem turn out to be the fantastic breakthrough in the valve field. The two valves did not only meet the requirement for stress and temperature at that time but also initially satisfy the require for flow regulation. Later, due to the fact of the fast improvement of power sector, oil industry, chemical market and shipbuilding market, all types of high or middle valves sprang up like mushrooms. What is additional, soon after the Second World War, owning to the invention of new components 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 create promptly.
All in all, step by step the valve manufacturing becomes 1 of the significant sectors in the mechanical market. There are a lot of applications for the valve. It is closely connected with our every day life. For instance, the tap utilized for running water pipe and the reducing valve employed for liquefied petroleum gas stove are the valves. What’s more, it is the crucial aspect for distinctive mechanical equipments such as gas engine, steam engine, compressor, pump, vehicle, ship or aerocraft.