Location:Home > About us > History
    Valves are devices used to control fluid flow, pressure and direction of flow. The controlled fluid can be liquid, gas, gas-liquid mixture or solid liquid mixture. Valves are usually made up of body, bonnet, valve seat, opening and closing parts, driving mechanism, seals and fasteners. The control function of valve is realized by driving mechanism or fluid driving the lifting, sliding, swinging or rotary motion of the opening and closing parts to change the size of the runner area. The use of the valve is very wide, it has a close relationship with people's daily life, for example, the tap water pipe and the pressure relief valve used in the liquefied petroleum gas stove are valves. Valves are also indispensable components of a variety of mechanical equipment, such as internal combustion engines, steam engines, compressors, pumps, pneumatic transmission devices, hydraulic transmission vehicles, ships and aircraft. Before two thousand B.C., Chinese people used bamboo pipes and cork valves on the water pipeline, then used sluices on irrigation channels, used plate check valves on the smelter's bellows, and extracted brine with bamboo tube and plate type check valve in the mining of well salt, and appeared in Europe with the development of smelting technology and hydraulic machinery. Copper and lead cock valves. With the use of boilers, a lever safety valve was developed in 1681. Plug valves and check valves were always the main valves before Watt's steam engine appeared in 1769. The invention of steam engine has made valves enter the field of mechanical industry. In addition to using plug valves, safety valves and check valves on Watt's steam engine, butterfly valves were also used to regulate flow. With the increase of steam flow and pressure, the use of stopcock to control the steam intake and exhaust steam of the steam engine can no longer meet the needs, so the spool valve appears.

Before and after 1840, there were successive cut-off valves with threaded stem and wedge gate valves with trapezoidal threaded stem, which is a major breakthrough in valve development. The emergence of these two types of valves not only met the requirements of various industries for increasing pressure and temperature at the time, but also initially met the requirements of flow regulation. Since then, with the development of electric power industry, petroleum industry, chemical industry and shipbuilding industry, various kinds of high and medium pressure valves have developed rapidly.

After the Second World War, the old cock valve and butterfly valve have obtained new applications due to the development of polymeric materials, lubricating materials, stainless steel and cobalt based cemented carbide. The ball valves and diaphragm valves have developed rapidly. Globe valves, gate valves and other valves increased and quality improved. Valve manufacturing industry has gradually become an important sector of the machinery industry. Valves can be divided into six categories: cut-off valve, regulating valve, check valve, shunt valve, safety valve and multi-purpose valve according to the use function.

The truncation valve is mainly used to cut off the fluid passage, including cut-off valve, gate valve, cock valve, ball valve, butterfly valve diaphragm valve, pinch valve and so on. The regulating valve is mainly used to regulate the pressure and flow of the fluid, including the regulating valve, throttle valve, pressure relief valve and floating ball regulating valve, etc. the check valve is used to prevent the reverse flow of the fluid; the diversion valve is used in the valve. The passage of the passage of a fluid, or separation of a two-phase fluid, including a slide valve, a multipass valve, a drain valve, and an air drain valve; the safety valve is used mainly for safety protection to prevent the destruction of the boiler, pressure vessel, or pipe due to overpressure; the valve is a valve with more than one function, such as a stop check valve which can both play the role of flow breakage and can be played. Stop action.

Industrial pipe valves can be divided into vacuum valve, low pressure valve, medium pressure valve, high pressure valve and ultra high pressure valve according to nominal pressure, and the valve can be divided into normal temperature valve, medium temperature valve, high temperature valve and low temperature valve at working temperature, and the valve can also be classified according to the type of the driving device, the connection mode with the pipe and the use material of the valve body. Valves can be named individually or in combination according to various classification methods, and can also be named according to the structural characteristics or specific purposes of the opening and closing parts.

The basic parameters of the valve are working pressure, working temperature and caliber. Nominal valves and nominal diameters are commonly used as basic parameters for various valves used in industrial pipelines. Nominal pressure refers to the maximum working pressure of a material valve under prescribed temperature. Nominal diameter refers to the nominal inner diameter of the connecting end of the valve body and the pipe.

Valves have different requirements according to their types and uses, mainly including sealing, strength, regulation, circulation, opening and closing. In the design and selection of valves, in addition to the basic parameters and properties, the performance of the fluid should be considered, including the phase state of the fluid (gas, liquid or solid particles), corrosion, viscosity, toxicity, flammability, explosive, precious and rarity and radioactivity.

Sealing performance and strength performance are the most basic and important properties of all valves. The valve is sealed in two parts: inner seal and outer seal. The inner seal is the seal between the valve and the valve seat; the outer seal is the seal between the valve stem moving part and the valve cover, the valve body and the valve cover, and the valve body and the pipe joint. Valves not only require good sealing performance, but also ensure safety.

If the leakage of the seal is not good and the strength is not enough, the parts will be damaged, which will cause the economic loss of different degrees, such as transporting poisonous, flammable and explosive or strong corrosive fluid, and may also cause serious safety accidents. In order to ensure the seal and strength of the valve, the material must be properly selected in addition to the proper design of the structure and the quality of the process in accordance with the relevant standards.

Usually, valves for low pressure non corrosive fluids are cast iron or cast copper; cast steel or forged steel for high and medium pressure valves; high temperature or high pressure valves.
Wenzhou Zhibo Mechanical Technology Co.,Ltd. All Rights Reserved 技术支持:捷创科技  浙ICP备10017617号