How to select the control valve

Selection note: visual inspection must be carried out, and the nameplate of the valve should comply with the provisions of the current national standard "General Valve Mark" GB 12220. For valves with working pressure greater than MPA and shut-off on the main pipe, strength and tightness performance tests should be carried out before installation, and they should be used only after they are qualified.

During the strength test, the test pressure is times of the nominal pressure, the duration is not less than 5min, and the valve housing and packing should be qualified without leakage.

During the tightness test, the test pressure is multiple of the nominal pressure; The test pressure should meet the requirements of GB 50243 standard for the duration of the test, and the sealing surface of the valve disc should be qualified if there is no leakage.

Choose the right brand, the valve produced by a good valve manufacturer is safe to use, and Shanghai Guardian valve is good.

Answer, support me.

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 influential first-line brands of water system valves and industrial valves can be used as a reference, but for reference only: Suzhou Neway Valve, Shanghai Guanlong Valve, Shanghai Qizhong Valve, 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.

How to select the control valve mainly refers to the following elements.

1. According to the process conditions, select the appropriate structural form and material. For example, the body material of the control valve is selected according to the characteristics of the medium, and the sealing material is selected according to the temperature.

2. According to the characteristics of the process object, select the flow characteristics of the Vton control valve. For example, there are linear, 100% and so on.

3. According to the process operation parameters, select the appropriate Vton control valve caliber size. For example, choose the right caliber according to the flow rate.

4. According to the requirements of the process, select the required auxiliary devices.

5. Reasonable selection of executive agencies. The response speed of the actuator should be sufficient for the process.

6. Choose self-powered, electric, pneumatic according to the energy source.

Requirements for control stroke time: The actuator of the selected Vton control valve should be able to meet the requirements of the valve stroke and the leakage level of the process. In some cases, such as the selection of pressure regulating valves (including vent valves), the actual possible pressure difference should be considered for appropriate amplification, that is, the actuator is required to provide a large force.

Otherwise, when there is an abnormal situation in the process, the actual pressure difference between the front and back of the regulating valve is large, and there will be a danger that it cannot be closed or opened.

If you ask about process valves, those are generally according to the caliber, and the requirements for adjustment accuracy are not high, and there are many enterprises in Fuyang, Zhejiang, and it is also more suitable.

If you need an industrial valve, then the selection of the control valve needs to use these parameters: valve front, valve pressure, medium, temperature, pipe diameter, dynamic viscosity, density, and then the general control valve companies have their own selection software, and these parameters can be entered into the selection.

Are you talking about industrial or building use, the selection method is different, first determine the medium, water or vapor or chemicals? The second is the adjustment or switching, as well as the material of the valve, cast copper, cast iron, cast steel? If it is an electric valve, the actuator is also selected, and the actuator must determine the signal.

Models are selected based on the manufacturer's product range.

So what is a control valve? The control valve, also known as the control valve, is the final control element in the field of industrial automation process control that changes the process parameters such as medium flow, pressure, temperature, and liquid level by accepting the control signal output by the regulation control unit and using power operation. It is generally composed of an actuator and a valve.

There are many types of control valves, how do we choose?

1. How to choose the model of the distribution control valve.

When choosing a control valve model, the first thing to consider is the functional aspect. According to the temperature, corrosion and other properties of the pipeline conveying medium, the temperature resistance, corrosion resistance (corrosion resistance, cavitation, erosion), anti-blocking, differential pressure p (including the normal working pressure difference, the differential pressure when the valve is closed), and the leakage should meet the process requirements. This aspect is mainly reflected in the body of the regulating valve.

In terms of regulating valve parameters, the selection of regulating valve parameters mainly includes the selection of action mode, adjustment speed, adjustable ratio verification, flow characteristics selection, valve caliber selection, and accompanying opening verification and other parameters. This item is mainly the selection of the technical parameters of the control valve actuator.

2. What are the models of control valves?

1) Pneumatic control valve.

Classified according to the form of pneumatic actuator.

a) Thin film actuators. It is also divided into straight-mounted type (positive action and reaction) and side-mounted type (positive action and action).

b) Piston actuator, which is divided into proportional type (positive and negative and two-position.

c) Long stroke actuator.

d) Rolling film actuators.

Classification according to the form of regulation: (a) modulation; (b) severance; (c) Adjustment cut-off type.

Classification by moving type: (a) linear stroke; (b) Angular travel.

Classified according to the shape of the spool: (a) flat spool; (b) Plunger-shaped spool; (c) window-shaped spool; (d) sleeve-shaped spool; (e) Multi-stage spool; (f) Deflector spool; (g) Butterfly spool; (h) Ball spool.

Classification according to flow characteristics: (a) straight line; (b) equal percentages; (c) parabola; (d) Quick open.

According to the form of the upper bonnet, the classification is quiet: (a) ordinary type; (b) Dispersion (heat absorption) type; (c) long-necked; (d) Bellows sealed type.

2) Electric control valve.

Classified according to the form of electric title mechanism: (a) angular stroke; (b) straight stroke; (c) Multi-turn type.

Classified by attachment form: (a) servo amplifier; (b) Limit switches.

Classification according to flow characteristics: (a) straight line; (b) equal percentages; (c) parabola; (d) Quick open.

Classified according to the form of the upper cover: (a) ordinary type; (b) Dispersion (heat absorption) type; (c) long-necked; (d) Bellows sealed type.

Selection principle of control valve:

1. According to the process conditions, select the appropriate structural form and material.

2. According to the characteristics of the process object, select the flow characteristics of the control valve.

3. According to the process operation parameters, select the appropriate caliber size of the regulating valve.

4. According to the requirements of the process, select the required auxiliary devices.

5. Reasonable selection of executive agencies. The response speed of the actuator should be sufficient for the process.

Requirements for control stroke time: The selected control valve actuator should be able to meet the requirements of valve stroke and process leakage level. In some cases, such as the selection of pressure regulating valves (including the venting Xiaohuai valve), the possible pressure difference of the actual Qiao companion should be considered for appropriate amplification, that is, the actuator is required to provide a large force.

Otherwise, when there is an abnormal situation in the process, the actual pressure difference between the front and rear of the regulating valve is large, and there will be a danger that it cannot be closed or opened.

The parameters required for the selection of pneumatic control valves include:

1. The type of medium (gas, liquid or steam).

2. The density macro state or specific gravity of the medium.

3. Pressure before and after the valve.

4. Flow rate and temperature.

The pneumatic control valve is to use compressed air as the power source, the cylinder as the actuator, and with the help of electrical valve positioners, converters, solenoid valves, position retention valves and other accessories to drive the valve, realize the switching or proportional adjustment, and receive the control signal of the industrial automation control system to complete the early adjustment of the pipeline medium: flow, pressure, temperature and other process parameters to shield the source.

Pneumatic control valves are characterized by simple control, fast response, and intrinsically safe conditions, without the need for additional explosion-proof measures.