A valve is a device for controlling the flow, pressure, and direction of a fluid. The controlled fluid may be a liquid, a gas, a gas-liquid mixture, or a solid-liquid mixture. Valve usually by the valve body, cover, seat, open and close pieces, drive mechanism, seals and fasteners, and so on. The control function of the valve depends on the driving mechanism or fluid to drive the lifting, sliding, swinging or rotating movement of the opening and closing parts to change the size of the runner area.
Valves have a wide range of uses and are closely related to people’s daily lives, such as taps for water pipes and pressure reducing valves for liquefied petroleum gas stoves. Valves are also essential components in a variety of mechanical equipment such as internal combustion engines, steam engines, compressors, pumps, pneumatic actuators, hydraulic drive system vehicles, ships and aircraft.
Before 2,000 BC, the Chinese used bamboo pipes and cork valves in water pipelines, water gates in irrigation canals, and plate check valves in smelting bellow with the development of smelting technology and hydraulic machinery, copper and lead plug valves have appeared in Europe. With the introduction of the boiler, 1681 introduced the lever hammer type safety valve. 1769 and check valves were the primary valves until Watt steam engine. The invention of the steam engine brought the valve into the field of the mechanical industry. In addition to the plug, relief and check valves used in Watt’s steam engines, butterfly valves are used to regulate flow. With the increase of steam flow and pressure, the use of a plug valve to control the steam intake and exhaust of steam engine can not meet the needs, so there is a slide valve.
Before and after 1840, there were globe valves with threaded stems and Wedge Valves with Trapezoidal threaded stems, which was a major breakthrough in valve development. The appearance of these two kinds of valves not only satisfied the increasing demand of pressure and temperature in various industries at that time, but also satisfied the demand of flow regulation. Since then, with the development of electric power industry, petroleum industry, chemical industry and shipbuilding industry, all kinds of high and medium pressure valves have been developed rapidly.
After the Second World War, due to the development of polymer materials, lubricating materials, stainless steel and cobalt-based carbide, the Old Plug Valve and butterfly valve have been used in new applications, ball valve and diaphragm valve have been developed rapidly. Globe valves, gate valves and other valves of increased variety and quality. Valve manufacturing industry has gradually become an important sector of the machinery industry. Valve according to the use of function can be divided into block valve, control valve, check valve, diversion valve, safety valve, multi-purpose valve 6 categories.
Post time: Jul-28-2021