[Science Stickers] Teach you how to choose a suitable valve

The significance of choosing the correct valve

In the fluid piping system, the valve is the control element, and its main function is to isolate the equipment and the piping system, adjust the flow, prevent backflow, adjust and drain the pressure. The correct selection of valves is essential to ensure the safe production of the device, increase the service life of the valve, and meet the long-term operation of the device. Since it is very important to choose the most suitable valve for the piping system, it is also important to understand the characteristics of the valve and the steps and basis for selecting the valve.

Principles of valve selection

Valves used in chemical production equipment should meet the following basic principles:

1. Reliability

Chemical production requires continuous, stable and long-term operation. Therefore, the required valve should have high reliability and a large safety factor. It should not cause major production safety and personal injury accidents due to valve failure; to meet the requirements of long-term operation of the device, long-term continuous production is the benefit.

2. Meet the requirements of process production

The valve should meet the requirements of operating medium, pressure temperature and purpose, which is also the most basic requirement for valve selection. For example, if the valve is required to protect against overpressure, safety valves and overflow valves should be used to discharge excess media; check valves should be used to prevent the backflow of media during operation.

3. Convenient operation, installation and maintenance

After the valve is installed, it should be able to enable the operator to correctly identify the valve direction, opening signs, and indication signals, so as to facilitate timely and decisive handling of various emergency faults. At the same time, the selected valve type structure should be as simple as possible and convenient for installation and maintenance.

4. Economy

Choose a valve with a reasonable price and a simple structure, and the general material can meet the requirements of use, and there is no need to choose a higher-grade material.

Steps to choose valve

The following steps are generally used to select the valve:

1. Clarify the purpose of the valve in the device or process pipeline, and determine the working condition of the valve, such as operating medium, operating pressure, and operating temperature.

2. Determine the type of valve according to the purpose of the valve: such as regulating valve, safety valve, open and closed circuit valve, etc.

3. Determine the form of the valve: According to the application and operating conditions, determine the valve type as: globe valve, ball valve, butterfly valve, diaphragm valve, check valve, bottom valve, etc.

4. Determine the valve Determine the method of operating the valve: manual, electric, pneumatic or hydraulic, electrical linkage or electro-hydraulic linkage, etc.

5. Determine the nominal parameters of the valve: the nominal pressure and nominal diameter of the valve should be determined to match the installed process pipeline. In general, when designing process piping, the applied standard system is the basis for determining the application standards of other components of the pressure piping. The valve is generally

Installed in the process pipeline. Therefore, its operating conditions should be consistent with the design and selection of the process pipeline. After the pressure level of the pipeline is determined, the nominal pressure, nominal diameter, and valve standard of the valve can be determined.

6. Determine the material of the valve: Determine the material of the shell and internal parts of the selected valve according to the medium, working pressure and working temperature of the process pipeline.

7. Determine the connection method of the valve and the pipeline: The connection between the valve section and the pipeline is determined by the operating conditions and adopts flange connection, socket welding, adhesive welding, hot melt butt welding, etc.

8. After the valve model is determined, the geometric parameters of the selected valve can be found: structural length, connection type and size, valve height when opening and closing, the size of the bolt hole connected, the overall size and weight of the valve, which lays the foundation for the on-site installation of the valve basis.

Basis for selecting valve

While understanding and mastering the steps of selecting a valve, it is also necessary to further understand the basis for selecting a valve.

1. The purpose, operating conditions and operation control mode of the selected valve.

2. The nature of the working medium: working pressure, working temperature, corrosion performance, whether it contains solid particles, whether the medium is toxic, whether it is a flammable or explosive medium, the viscosity of the medium, etc.

3. Requirements for valve fluid characteristics: flow resistance, discharge capacity, flow characteristics, sealing level, etc.

4. Requirements for installation dimensions and external dimensions: nominal diameter, connection to the pipeline and connection dimensions, external dimensions or weight restrictions, etc.

5. Additional requirements for the reliability, service life and explosion-proof performance of electric devices of valve products.

This article comes from the Internet, only for learning and communication, no commercial purpose.

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