The technical principle of the automatic control valve, please explain what is the working principle

Self-controlled valves refer to the use of electric, pneumatic, hydraulic or electromagnetic drive and other methods other than human power to control the valve. Its characteristics are: easy to use and safe; It can be controlled on-site or remotely; It can control a single valve or a centralized control of multiple valves; It can be controlled by simple on/off or adjusted; With the electronic computer, it can realize programmatic control.

Due to the need for long-distance control, there is generally a valve signal feedback - lamp signal or 4 20mA signal feedback for valve control.

Which is the best manufacturer of valves in Shanghai? There are many valve manufacturers in Shanghai, specifically which one is the best, in fact, it is very difficult, this depends on where you can evaluate it conveniently, each manufacturer produces different valve products, and the fields involved are also very different, for example, some are doing water systems, some are doing industrial systems, and industrial systems are divided into many fields, such as: electric power, chemical industry, petroleum, pharmaceuticals and many other fields.

Here is a brief introduction to a few companies, Shanghai Qizhong valve in the field of water system, Suzhou Neway valve, Shanghai Guanlong valve this unit is not bad, industrial valve field can also be.

Here are some of the well-known brands recognized in the valve industry, which are widely recognized and have a high reputation. Although the ranking may change due to time and market conditions, the following brands are generally considered to be one of the top brands in the valve industry: water system valves and industrial valves The following more influential first-line brands can be used as a reference, and the following are the top ten domestic first-line valve brand manufacturers in 2022-2023, but for reference only:

Suzhou Neway Valve, Shanghai Guanlong Valve, Shanghai Qizhong Valve, Sanhua, Suyan, 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.

Summary. Hello dear! An automatic valve is a pump protection device.

It automatically protects centrifugal pumps, especially those transporting hot water media, from partial cavitation damage and instability that may occur in the pump body when operating at low loads. Once the pump flow falls below the preset flow, the bypass is fully opened to ensure the pump needs a small flow rate. Even if the main circuit is fully closed, i.e. the main flow is zero, small flows can be automatically circulated by bypass.

The pressure is reduced by an integrated multi-stage throttle regulator in the bypass. The automatic circulation valve has a large diameter bypass, this valve is used for large bypass flow rates, and the differential pressure is as large as 4MPa.

Hello dear! An automatic valve is a pump protection device. It automatically protects centrifugal pumps, especially those transporting hot water media, from partial cavitation damage and instability that may occur in the pump body when operating at low loads.

Once the pump flow falls below the preset flow, the bypass is fully opened to ensure the pump needs a small flow rate. Even if the main road is completely closed and the main road flow is zero, the small flow can be automatically circulated through the bypass. The pressure is reduced by an integrated masking multi-stage throttle regulator in the bypass.

The automatic circulation valve has a bypass with a large mouth diameter and is used for larger bypass flows, with a differential pressure of up to 4MPa.

The automatic circulation valve integrates four functions: 1. Flow sensing: The main valve disc can automatically sense the main flow in the process system, so as to determine the position of the main valve disc and the bypass valve disc according to this flow rate.

2. Recirculation control: The small flow required for the normal operation of the pump can be sucked into the storage device through the bypass, and the H-Q characteristics of the pump can be adjusted to achieve recirculation. 3. Bypass multi-stage decompression:

The bypass control system can reduce the high pressure of the reflux medium from the pump outlet to the low pressure suitable for the reflux storage device with low noise and low wear. 4. Non-return: It is also equipped with an automatic circulation valve to prevent the liquid from flowing back into the pump body.

ZDT bypass check is optional.

Please explain in detail the construction process of fire pipe burial anti-corrosion treatment.

1. The anti-corrosion of buried pipelines requires that the thickness of epoxy coal asphalt ordinary grade is greater than the process: first apply a layer of primer, and then apply three layers of paint; The thickness of the reinforced asphalt paint of the front ridge of epoxy coal is greater than that of a layer of primer first, then a topcoat, then a glass cloth, then a topcoat, a layer of glass cloth, and finally two layers of paint. 2, epoxy coal asphalt paint extra reinforced thickness greater than first apply a layer of primer, then coat the topcoat, wrap a layer of glass cloth, then coat the topcoat, wrap a layer of glass cloth, then coat the topcoat, wrap a layer of glass cloth, and then coat two layers of paint, epoxy coal asphalt is now the most suitable ambient temperature for construction 5 30.

3. If the anti-corrosion of the external network buried pipeline is used in the harsh environment, or under the customer's wild demand, the topcoat and glass cloth can be added to increase the anti-corrosion ability and level. The anti-corrosion of buried pipelines is mainly natural gas, oil pipeline network system, cold and hot water pipeline network, high-temperature steam pipeline network, sewage pipeline network system, fire external network pipe network system, domestic water supply system, etc.

The safety valve is mainly composed of three parts: the seat, the disc (spool) and the loading mechanism. Some of the valve seats are integrated with the valve body, and some are assembled with the valve body, which communicates with the equipment. The disc is often attached with a stem, which is tightly attached to the seat.

Above the disc is a loading mechanism, and the size of the load can be adjusted. When the pressure in the equipment is within a certain working pressure range, the force of the internal medium acting on the valve disc is less than the force added by the loading mechanism on the valve, and the difference between the two constitutes the sealing force between the valve disc and the valve seat, so that the valve disc is pressed against the valve seat, and the medium of the equipment cannot be discharged. When the pressure in the equipment exceeds the specified working pressure and reaches the opening pressure of the safety valve, the force of the internal medium acting on the alarm valve is greater than the force exerted on it by the loading mechanism, so the valve disc leaves the valve seat, the safety valve is opened, and the medium in the equipment is discharged through the valve seat, if the displacement of the safety valve is greater than the safe release amount of the equipment, the pressure in the equipment gradually decreases, and after a short period of exhaust, the pressure drops back to the normal working pressure.

At this time, the force of the internal pressure acting on the valve disc is less than the force exerted on it by the loading mechanism, and the valve disc is pressed against the valve seat again, the medium stops discharge, and the equipment continues to operate at normal working pressure. Therefore, the safety valve is closed or opened by itself to prevent the equipment from overpressure by the force of the medium on the disc and the force of the loading mechanism.

The principle of the globe valve is to use the torque of the valve stem to give a downward pressure to the sealing surface, and rely on the pressure of the valve stem to make the sealing surface of the valve disc and the sealing surface of the valve seat fit tightly, so as to prevent the inflow of the medium or adjust the flow rate of the medium. The opening and closing parts of the globe valve are cylindrical discs, the sealing surface is flat or conical, and the disc moves in a straight line along the center line of the fluid.

The self-operated pressure regulating valve controls the opening and closing of the valve according to the pressure in the pipeline and its own spring force to cut off the medium in the pipeline.

1. The electric valve is usually connected by an electric actuator and a valve, and becomes an electric valve after installation and commissioning. The electric valve uses electric energy as the power to connect the electric actuator to drive the valve, and realize the opening and closing and adjusting of the valve. So as to achieve the purpose of switching or adjusting the pipeline medium.

2. The drive of the electric valve is generally driven by a motor, and it takes a certain amount of time to simulate the opening or closing action, which can be adjusted. Relatively resistant to voltage shocks. The solenoid valve is quick to open and close quickly, and is generally used in places with small flow and low pressure and large switching frequency; Electric valves are reversed.

The opening of the electric valve can be controlled by the experience, and the state is open, closed, half-open and half-closed, which can control the flow of the medium in the pipeline and the solenoid valve can not meet this need. The three-wire electric valve has three lines, F and N, F stands for forward action (or open action) control line, R stands for reverse action (or close action) control line, and N stands for ground line. Solenoid valves are a type of electric valves; It is to use the magnetic field generated by the electromagnetic coil to pull the valve core, so as to change the on-off of the valve body, the coil is powered off, and the valve core is retracted by the pressure of the spring.