What Is a Pressure Reducing Valve?

The pressure reducing valve is a valve that adjusts the inlet pressure to a certain required outlet pressure and relies on the energy of the medium to automatically maintain a stable outlet pressure. From the point of view of fluid mechanics, the pressure reducing valve is a throttle element whose local resistance can be changed, that is, by changing the throttle area, the flow velocity and the kinetic energy of the fluid are changed, resulting in different pressure losses, thereby achieving the purpose of pressure reduction. Then rely on the adjustment of the control and adjustment system to balance the fluctuation of the pressure behind the valve with the spring force, so that the pressure behind the valve remains constant within a certain error range.

This is a typical hydropower station

Standard one on a given spring

China's valve industry chain is numerous, but not a valve powerhouse. On the whole, China has entered the ranks of the world's valve powers, but from the perspective of product quality, there is still a long gap between China and the valve powers. The industry's low concentration of production, low R & D capabilities of valves supporting high-end products, and low manufacturing technology in the valve industry still exist, and the import and export trade deficit continues to expand.

The next few years will be a period of high-speed shocks in the valve industry. The direct consequence of such high-speed shocks is the expansion of the polarization trend in the valve cabinet brand camp. There are definitely not so many valve companies that can really survive the market in the next few years. However, this high-speed shock of the valve industry will bring huge opportunities, and the results of the shock will make the market operation more rational.

The localization of high-end valves is unusually bumpy. Basic parts have become a short board that restricts the development of high-end manufacturing in China. During the 12th Five-Year Plan period, the government will continue to increase the localization of high-end equipment components. Here we select several representative valves in key development industries mentioned in the "Implementation Plan" for feasibility analysis of import substitution. From the analysis, we can see that the feasibility of import substitution of valves in various sub-sectors is very different. High-end valves need more policy guidance and scientific research support.

The valve industry plays a very important role in the development of the national economy as an important link in preparing the manufacturing industry. As China's domestic valve manufacturing industry still has a certain gap compared with the international advanced level, many key valves with high parameters, high temperature, high pressure and high pounds have always depended on imports. After the "Several Opinions of the Equipment Manufacturing Industry", the relevant state departments have made a series of major deployments in accordance with the national requirements for major equipment localization, and are led by the National Development and Reform Commission. Deployed and formulated valve localization plans for major equipment in related fields, and coordinated with relevant departments many times. Nowadays, valve localization has reached a consensus in the domestic valve industry.

Actively adopt international standards for product design; absorb excellent design structures from abroad; product tests and performance inspections are carried out in strict accordance with international standards; absorb foreign production process experience and attach importance to the research and promotion of new materials; clarify the technology of imported high-parameter valve products Parameters and working conditions are a way to speed up the localization process, promote the continuous updating of valve products, and fully realize the localization of valves.

With the acceleration of the restructuring of the valve industry, the future industry will be competition between valve product quality and safety and product brands. The products will develop in the direction of high technology, high parameters, strong corrosion resistance, and long life. Only through continuous technological innovation and development New products and technical transformation can gradually improve the technical level of the product, meet the domestic equipment supporting, and fully realize the localization of the valve. China's valve manufacturing industry will present a better development prospect under the huge demand environment.

Setter is one

Pressure reducing valve

This kind of high precision pressure reducing valve is mainly used for pressure setting. At present, there are two types of pressure gauges: the gas source pressure is 0.14MPa and 0.35MPa, and the output pressure ranges are 0-0.1MPa and 0-0.25MPa. Its output pressure fluctuation is not more than 1% of the maximum output pressure, and it is often used in situations where precise air source pressure and signal pressure need to be supplied, such as pneumatic experimental equipment and pneumatic automatic devices.

The working principle of the potentiometer. It consists of three parts: 1 is the main closed part of the direct-acting pressure reducing valve; 2 is a constant pressure drop device, which is equivalent to a certain differential pressure reducing valve. The main function is to make the nozzle get stable air source flow; 3 is the nozzle baffle device and pressure regulating part, which plays the role of pressure regulation and pressure amplification, and uses the amplified air pressure to control the main valve part.

Because the potentiometer has the functions of setting, comparing and amplifying, the voltage regulation accuracy is high.

When the potentiometer is in a non-working state, the compressed air input from the air source is filtered by the filter 1 and enters the A room and the positive room. The main valve core 19 is pressed against the valve seat by the spring 20 and the pressure of the air source, so that the A room and the B room are disconnected. The airflow entering the A room passes through the valve port (also known as the valve) 12 to the F room, and then decreases the pressure through the constant orifice 13 to enter the G room and the D room respectively. Since no force is applied to the diaphragm 8 at this time, the distance between the baffle 5 and the nozzle 4 is large, and the resistance of the gas flow when the gas flows out from the nozzle 4 is small. The pressure in the G and D chambers is low. 15 Keep the original position. The trace gas entering only the chamber is mainly discharged from the exhaust port through the valve port 2 through the B chamber; another part is evacuated from the output port. At this time, there is no airflow output from the output port, and the exhaust of the trace gas from the nozzle is necessary to maintain the operation of the nozzle baffle device. Because it has no power consumption, it is desirable that the consumption is as small as possible.

When the potentiometer is in the working state, turn the handle 7, press down the spring 6, and push the diaphragm 8 together with the baffle 5 to move down. The gap between the baffle 5 and the nozzle 4 is reduced, and the airflow resistance increases. The air pressure rises. The diaphragm 16 is moved down under the pressure of the D chamber, and the valve port 2 is closed, and the main valve core 19 is pushed downward to open the valve port. The compressed air is output from the output ports through the B and H chambers. At the same time, the pressure in the H chamber rises and is fed back to the diaphragm 8. When the feedback force received by the diaphragm 8 is balanced with the spring force, the potentiometer outputs a certain pressure of gas. When the input pressure fluctuates, for example, the pressure rises, the pressure in the B and H chambers instantly increases, causing the diaphragm 8 to move up, resulting in an increase in the distance between the baffle 5 and the nozzle 4, and the pressure in the G and D chambers decreases. As the pressure in the B chamber increases, the pressure in the D chamber decreases, and the diaphragm 15 moves upward due to the pressure difference, so that the main valve port

Pressure reducing valve

Decreasing, the output pressure drops until it stabilizes to the set pressure. In addition, when the input pressure rises, the pressure in the E chamber and the instantaneous pressure in the F chamber also rise, and the diaphragm 3 moves upward under the effect of the upper and lower differential pressure, and closes the small regulator valve port 12. As the throttling effect is strengthened, the pressure in the F chamber decreases, and the pressure difference between the front and rear orifices 13 is always kept constant. Therefore, the gas flow rate through the orifice 13 is unchanged, and the sensitivity of the nozzle baffle is improved. When the input pressure decreases, the pressures in the B and H chambers decrease instantaneously. The diaphragm 8 and the baffle plate 5 move downward due to the failure of the force balance. The distance between the nozzle 4 and the baffle plate 5 decreases, and the pressure in the G and D chambers increases The diaphragms 3 and 15 move down. The downward movement of the diaphragm 15 increases the opening degree of the main valve, and the air pressure in the B and H chambers rises until it is balanced with the set pressure. And the diaphragm 3 moves downward, so that the pressure-stabilizing port 12 is widened, and the pressure in the F chamber rises, and the pressure difference between the front and back of the constant orifice 13 is always kept constant. Similarly, when the output pressure fluctuates, the same adjustment will be obtained when the input pressure fluctuates.

Because the potentiometer uses the feedback effect of the output pressure and the enlargement of the nozzle baffle to control the main valve, it can respond to small pressure changes, so that the output pressure can be adjusted in time, and the outlet pressure is basically stable, that is, the fixed value. The voltage regulation accuracy is high.