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This post was last edited by Ceramic Valve World on 2020-8-10 13:01. As a control device for fluid pipelines, valves came into being with the creation of pipelines. The most basic function of the valve is to connect or cut off the flow of pipeline media. Valves can be used to change the flow direction of the medium in the pipeline, adjust the pressure and flow of the medium, and protect the safe operation of the pipeline. Humans have a long history of understanding and using valves. Let's take a look, what is the development history of valves? The Nile River is the cradle of ancient Egyptian civilization. However, this river originating from the south floods the land along its banks every year. Although the floods left fertile soil behind, they also destroyed crops and houses. In order to prevent the Nile from flooding again and again, the ancient Egyptian people dug canals all year round to dredge the waterways. So how do they control the distribution of water? They made a rotatable stopper out of wood, which was the early plug valve. Because of its simple structure and ease of use, it only requires a quarter turn to complete the switching action, so it was the earliest device used to control pipeline fluids. Two thousand years ago, there were bronze plug valves in ancient Rome, and their structural forms were basically the same as modern plug valves. Ancient valves had poor adjustment performance and serious leakage, and were mostly used in water control projects. With the development of metallurgical technology, in the thirteenth century, metal valves were used on containers for experimental devices. The ancient Chinese people also used valves very early in their long-term production practice. For example, Yunnan and Sichuan provinces are far away from the coast and have very inconvenient transportation. Therefore, it is very difficult to transport sea salt inland, but there is a large amount of salt underground in these two provinces. On the rocky mountains not far from the river, most wells can be built to extract salt. The circumference of the salt wells is only a few inches in size. The specific mining methods are detailed in "Tiangong Kaiwu" compiled by Song Yingxing, a scientist in the late Ming Dynasty.: “Behind wells and springs, choose beautiful bamboos that are ten feet long and chisel out the joints, leaving the bottom intact. There is a message under its throat, and water is sucked into the tube." "Message" in this article refers to the mechanism, which can be understood as a one-way valve. The valve is installed at the lower end of the bamboo tube. When the bamboo tube sinks to the bottom of the well, the valve is opened by the upward pressure of the brine. ； When the bamboo tube is lifted, the valve is pressed down by the gravity of the brine in the tube and closed. Using this, coupled with a simple lever tool, you can continuously draw up the brine. Although humans have used valves for nearly four thousand years, they have long been restricted by the production conditions at that time, so the structure, performance and scope of application of valves have not changed much. It was not until the eighteenth century British inventor James Watt made a large number of improvements to the primitive steam engines that had already appeared at that time that the thermal efficiency of steam engines was improved. * * Improved, working stability and reliability were also enhanced, so steam engines were soon widely used in the industrial sector. Since steam engines use high-temperature and high-pressure steam, the requirements for boilers have increased, making it difficult for plug valves to continue to be used, and people must look for new valves. At that time (1795~1800), spiral cutting lathes had been widely used, so a new structure—the spiral lift stop valve—came into being. With the increase of steam pressure and temperature parameters, in order to prevent boiler explosion accidents, safety valves were born. Obviously, valves are widely used in industry, starting with Watt's invention of the steam engine. In the 19th century, the second industrial revolution marked by the application of electric energy began. Steam generators developed towards large-scale. * * This has greatly promoted the further development of industrial valves. In 1839, the British James Nathmy invented the wedge gate valve. In 1880, Willam Fisher, an engineer at the Marshall Town Municipal Water Plant in the United States, had to manually operate the valve 24 hours a day to maintain the discharge pressure of the steam-driven water pump. The elimination system required continuous adjustment to ensure sufficient pressure and flow of water to extinguish the fire. After a long period of exploration, Willam Fisher invented a constant pressure pump regulator (control valve). By 1907, these regulators had been installed in power plants in the United States, Canada, and the United Kingdom. In 1882, William B. Mason, a chief engineer on a steam-driven ship. Patents were filed for pump speed controllers, a steam pressure reducing valve in 1885, and a pump pressure regulator in 1886. The principle of a ball valve or spherical plug valve dates back to the 19th century, with John Warren receiving the first patent for a metal-seated ball valve in 1871 (Patent No. 0117704). Over the next 60-70 years, other ball valve designs emerged, but the effective soft-seat ball valve was functionally one-way only. The problem at the time was how to make a two-way soft-seat ball valve. After the 1920s, the rapid development of the petroleum and electric power industries promoted the further development of the valve industry. Cast steel valves, cast valves and alloy steel high temperature and high pressure valves appeared successively. ； At the same time, the structure of the valve is constantly updated, and the valve sealing surface begins to use cobalt-chromium-tungsten carbide. The sealing performance and regulating performance of the valve have been improved, and various basic types of valves have gradually formed. In 1920, the technology of cracking crude oil under high temperature and high pressure appeared. During this period, a series of self-operated regulating valves were invented, as well as some cutting-edge temperature and pressure control instruments. At this time, automatic regulating valve applications and technology began to develop rapidly, and the idea of using 15psi pressure to drive the actuator began to be implemented. The valve positioner was invented in 1936, and the problem of insufficient driving force of the actuator was finally overcome. The original positioner had a mechanical feedback device to sense the position of the valve stem, and a bellows system. The original positioners were also equipped with a manual device to reset the control. Today's positioners have a bypass switch that does not require the controller to be reset. By 1940, the concept of using a valve positioner to solve the problem of insufficient actuator output force was established, and people's focus began to shift to the development of reasonably sized actuators and single-seat valve structures. The emergence of new synthetic sealing materials such as polytetrafluoroethylene and nylon in the 1930s opened up a broad road for the application and development of ball valves and butterfly valves. By 1954, butterfly valves began to be produced and used as control valves. As a rotary automatic valve, as we know, the application of butterfly valves is limited due to the small output force of the actuator and the limitation of the rotation angle. It was not until 1950 that an actuator with greater driving force was assembled on the butterfly valve to overcome the instability of butterfly valve control and opened up a wider range of applications. In recent decades, various extreme temperature projects such as petroleum, chemical industry, electric power, new energy, etc. have developed rapidly on an unprecedented scale, requiring higher performance of valves and greater output requirements. In the future, the development trend of valves is: High parameters, high performance, high life valve material with high strength and corrosion resistance ； Enlargement or miniaturization of caliber ； Diversification and linkage of transmission methods ； Standardization, generalization and serialization of valve types and specifications.