In pipeline engineering, the correct selection of electric valves is one of the guarantee conditions to meet the requirements of use. Improper selection of electric valves will not only affect the use of the valves, but also bring adverse consequences or serious losses. Therefore, electric valves should be selected correctly in pipeline engineering design. 1. Working environment of electric valve besides the pipeline parameters, electric valve should pay special attention to its working environment conditions, because the electric device in electric valve is an electromechanical device, and its working condition is greatly affected by its working environment. In general, the operating environment of electric valves is as follows:

1. Indoor installation or outdoor use with protective measures;

2. Outdoor outdoor installation with wind, sand, rain, sunlight and other erosion;

3. Having an environment of inflammable, explosive gas or dust;

4. Environment in hot and humid zones and dry tropics;

More than 5, pipes, medium temperature up to 480 ℃;

6 below - 20 ℃, environment temperature;

7. Easy to be flooded or immersed in water;

8. Having the environment of radioactive materials (nuclear power plant and radioactive material test equipment);

9. The environment on the ship or dock (with salt mist, mould and humidity);

10. Places with severe vibration;

11. Places prone to fire; For the electric valve in the above environment, its electric device structure, materials and protective measures are all different. Therefore, the corresponding valve electric device should be selected according to the above working environment.

According to the requirement of engineering control, the control function of electric valve is accomplished by electric device. The purpose of using electric valve is to realize non-manual electrical control or computer control of valve opening, closing and adjusting linkage. The current electric devices are not only used to save manpower. Because the function and quality of products from different manufacturers are quite different, it is equally important to choose electric devices and valves.

Due to the continuous improvement of industrial automation level, the electric control of electric valves is increasingly used. On the one hand, the control requirements of electric valves are getting higher and more complex. Therefore, the design of electric valve in electric control side is also constantly updated. With the development of science and technology and the popularization and application of computers, new and diversified electric control methods will appear continuously. Considering the overall control of electric valve, attention should be paid to the control mode of electric valve. For example, according to the engineering needs, whether to use centralized control mode, single control mode, whether to link with other devices, program control or application computer program control, etc., the control principle is different. The valve electric device manufacturer's sample only gives the standard electric control principle, so the use department should conduct the technical disclosure with the electric device manufacturer to clarify the technical requirements. In addition, when selecting electric valves, consideration should be given to the additional purchase of electric valve controllers. Because in general, controllers need to be purchased separately. In most cases, when a single control is adopted, the controller needs to be purchased, because it is more convenient and cheaper to purchase than the controller designed and manufactured by the user. When the electrical control performance cannot meet the requirements of engineering design, the modification or redesign should be proposed to the production plant.

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