Classification of self operated control valves, what are the characteristics of self operated pressu

Self-operated control valves are divided into two types: direct-acting and indirect-acting. Indirect-acting control valve, with the addition of a commander (pilot valve), which plays the role of amplifying the feedback signal, and then drives the movement of the main valve disc through the actuator to achieve the purpose of changing the valve opening.

In the case of a pressure regulating valve, the feedback signal is the outlet pressure of the valve, which is introduced into the actuator through the signal tube.

If it is a flow regulating valve, there is an orifice plate (or other resistance device) at the outlet of the valve, and the differential pressure signal is taken out from both ends of the orifice plate and introduced into the actuator.

If it is a temperature regulating valve, there is a temperature sensor (or temperature bag) at the outlet of the valve to drive the actuator through the thermal expansion and contraction of the medium in the temperature sensor.

Here are some of the well-known brands recognized in the valve industry, which are widely recognized and have a high reputation. While rankings may vary depending on time and market conditions, the following brands are generally considered to be among the top brands in the valve industry:

The following are the top ten domestic first-line valve brand manufacturers in 2022-2023, but for reference only: Suzhou Neway Valve Co., Ltd., Shanghai Guanlong Valve Machinery, Shanghai Qizhong Valve Manufacturing, Sanhua, Su Yan, Shentong, Su Valve, Nanfang, Jiang.

First, the word Yao. The above manufacturers are only estimates and references, and the specific situation may vary or fluctuate at any time due to changes in a series of factors such as changes in the market, the size of the competition pattern, and the stability of product quality. As an indispensable key device in industrial production and civil facilities, the quality and reputation of the valve brand directly affect the satisfaction and trust of users.

These brands are known in the valve industry for their innovative technology, high-quality products and reliability. It is important to note that the market and industry are evolving rapidly, and different rankings may vary depending on time and region. For the most up-to-date ranking information, it is recommended to refer to industry reports, professional organizations or market research data for more detailed and accurate information.

The larger feature of the self-operated pressure group Kaichang control valve is that it can work in the field without gas and electric energy, and the preset pressure can be adjusted arbitrarily during operation. Sensitive action, good sealing performance, in the automatic control system of various equipment vapor, liquid, and vapor medium to relieve pressure, pressure stabilizer pipe (used for post-valve pressure adjustment) or pressure relief, pressure stabilizer pipe (for pre-valve pressure adjustment) automatic control valve. According to the different working conditions of users, different types of valve core structure shapes and different actuators can be selected to achieve the effect.

Self-operated control valves are divided into three series: self-operated pressure, differential pressure and flow control valves. The self-operated pressure regulating valve is divided into two types according to the position of the pressure point, the front of the valve and the back of the valve, and when the pressure point is in front of the valve, it is used to regulate the constant pressure in front of the valve; When the pressure point is behind the valve, it is used to adjust the pressure behind the valve to be constant. When the pressure before and after the valve is introduced into both sides of the air chamber of the actuator at the same time, the self-operated differential pressure regulating valve can adjust the constant pressure at both ends of the regulating valve, and the pressure difference installed at both ends of the orifice plate installed on the pipeline can also be introduced into the two sides of the air chamber of the membrane actuator with the ballast to form a self-operated flow regulating valve, or the flow rate can be adjusted by using the self-operated differential pressure regulating valve after the flow is detected in other ways.

Relying on the pressure and temperature of the medium flowing through the valve itself as the energy source to drive the valve to work automatically, there is no need for external power supply and secondary instruments. This kind of self-operated control valve uses the feedback signal (pressure, differential pressure, temperature) at the output end of the valve to transmit to the actuator through the signal tube to drive the valve disc to change the opening of the valve, so as to achieve the purpose of regulating the pressure, flow rate and temperature. Garment wholesale control valves are divided into two types: direct-acting and indirect-acting.

The direct-acting type is also known as the spring-loaded type, and there are elastic spike bucket leather parts in its structure: such as springs, bellows, bellows, bellows, etc., which are balanced by elastic force and feedback signal.

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Self-operated control valve [provided by Shanghai Shanbai valve] self-operated control valve principle: relying on the pressure and temperature of the medium flowing through the valve as energy to drive the valve to work automatically, without the need for external power supply and secondary instruments. This is called a self-operated control valve.

There are two types of pressure before the control valve and after the control valve.

The self-operated valve that controls the pressure in front of the valve is called the back pressure valve, which adjusts the opening of the spool by sensing the change of the pressure in front of the valve, so as to realize the pressure in front of the control valve at the set point. For example, if the pressure in front of the valve is higher than the desired set point, then open the valve core a little more, release the pressure, and reduce the pressure in front of the valve until the pressure reaches the set point. If the pre-valve pressure is sensed to be lower than the desired set point, open the spool a little smaller and hold the pressure to increase the pre-valve pressure until the pressure reaches the set point.

The self-operated valve that controls the pressure behind the valve is called the pressure reducing valve, which adjusts the opening of the valve core by sensing the change of the pressure behind the valve, so as to control the pressure behind the valve at a set point. If the post-valve pressure is sensed to be higher than the desired set point, open the spool a little smaller and reduce the post-valve pressure until the pressure reaches the set point. If the post-valve pressure is sensed to be lower than the desired set point, open the spool a little more and increase the post-valve pressure until the pressure reaches the set point.

The working principle of the self-operated pressure regulating valve (post-valve pressure control).

After the valve pressure P1 of the working medium passes through the throttle behind the valve core and the valve seat, it becomes the pressure behind the valve and is input into the lower membrane chamber of the actuator through the control pipeline and acts on the top plate, and the resulting force is balanced with the reaction force of the spring, which determines the relative position of the valve core and the valve seat, and controls the pressure behind the valve. When the pressure p2 increases behind the valve, the force exerted by p2 on the top plate also increases. At this point, the force acting on the top plate is greater than the reaction force of the spring, so that the spool closes to the position of the valve seat until the force acting on the top plate is balanced with the reaction force of the spring.

In this case, the flow area between the spool and the seat is reduced, and the flow resistance becomes larger, so that P2 is reduced to the set value. In the same way, when the post-valve pressure P2 is reduced, the direction of action is opposite to the above, which is the working principle of the self-operated (post-valve) pressure regulating valve.

2. The working principle of the self-operated pressure regulating valve (pre-valve pressure control) The pre-valve pressure P1 of the working medium becomes the post-valve pressure P2 after the throttling behind the valve core and valve seat. At the same time, P1 is input into the upper membrane chamber of the actuator through the control pipeline and acts on the top plate, and the resulting force is balanced with the reaction force of the spring, which determines the relative position of the valve core and the valve seat, and controls the pressure in front of the valve. When the post-valve pressure P1 increases, the force exerted by P1 on the top plate also increases.

In this case, the force acting on the top plate is greater than the reaction force of the spring, causing the spool to move in the direction of leaving the seat until the force acting on the top plate is balanced by the reaction force of the spring. In this case, the flow area between the spool and the seat is reduced, and the flow resistance is reduced, so that P1 is reduced to the set value. In the same way, when the post-valve pressure P1 is reduced, the direction of action is opposite to the above, which is the working principle of the self-acting (pre-valve) pressure regulating valve.