Security:
1, corrosive media: plastic king solenoid valve and stainless steel should be selected; The isolation diaphragm type must be used for the strong corrosive medium. Neutral medium, it is also appropriate to choose copper alloy for the valve shell material of the solenoid valve, otherwise, the valve shell often rust chips off, especially in the case of infrequent action. Ammonia valve can not use copper.
2, explosive environment: must choose the corresponding explosion-proof grade products, open installation or dust occasions should choose waterproof, dust-proof varieties.
3, the nominal pressure of the solenoid valve should exceed the highest working pressure in the tube.
Applicability:
1. Medium characteristics
1) Quality gas, liquid or mixed state respectively choose different varieties of solenoid valve;
2) Medium temperature products of different specifications, otherwise the coil will burn, seal aging, seriously affect the service life;
3) Medium viscosity, usually below 50cSt. If more than this value, diameter greater than 15mm, with multifunctional solenoid valve; Diameter less than 15mm, with high viscosity solenoid valve.
4) When the cleanliness of the medium is not high, the backwash filter valve should be installed in front of the solenoid valve. When the pressure is low, direct acting diaphragm type solenoid valve can be used;
5) If the medium is directional flow, and does not allow backflow, need to use two-way flow;
6) Medium temperature should be selected within the allowable range of the solenoid valve.
2. Pipeline parameters
1) Select the valve opening and model according to the medium flow direction requirements and pipeline connection mode;
2) According to the flow rate and valve Kv value selected nominal diameter, also can choose the same pipe diameter;
3) Working pressure difference: the lowest working pressure difference above 0.04Mpa can be used indirect pilot type; If the minimum working pressure difference is close to or less than zero, direct acting type or step by step direct type must be used.
3. Environmental conditions
1) The maximum and minimum temperature of the environment should be selected within the allowable range;
2) In the environment of high relative humidity and water droplets rain, waterproof solenoid valve should be selected;
3) In the environment often vibration, turbulence and impact occasions should choose special varieties, such as Marine solenoid valve;
4) Use in corrosive or explosive environment should be preferentially selected according to safety requirements of corrosion resistant type;
5) If the environmental space is limited, the multifunctional solenoid valve should be selected, because it eliminates the bypass and three manual valves and is convenient for online maintenance.
4. Power supply conditions
1) According to the type of power supply, choose AC and DC solenoid valves respectively. Generally speaking, AC power supply is convenient to access;
2) AC220V.DC24V is preferred for voltage specification;
3) Power supply voltage fluctuation usually AC selection +%10% -15%, DC allowed ±%10, if out of tolerance, must take voltage regulation measures;
4) The rated current and power consumption should be selected according to the power supply capacity. It should be noted that the VA value is high when AC starting, and the indirect pilot solenoid valve should be preferred when the capacity is insufficient.
5. Control accuracy
1) The common solenoid valve only open, close two positions, in the control accuracy requirements and requirements of stable parameters need to choose more than one solenoid valve;
2) Operation time: refers to the time when the electric signal is connected or cut off until the main valve is completed;
3) Leakage: The leakage value given on the sample is the common economic grade.
Reliability:
1. Working life, which is not included in the ex-factory test item, belongs to the type test item. To ensure quality should choose regular manufacturers of famous brand products.
2. Working system: Divided into long-term working system, repeated short-time working system and short-time working system. For a long time valve open only short time closed, it is appropriate to choose normally open solenoid valve.
3. Working frequency: When the frequency of action is high, the structure should be preferred to direct acting solenoid valve, and the power supply should be preferred to AC.
4. Operation reliability
Strictly speaking, the test has not been formally included in the Chinese solenoid valve professional standards, in order to ensure the quality of the regular manufacturers should choose famous brand products. Some occasions are not much action, but the reliability requirements are very high, such as fire, emergency protection, must not be taken lightly. Especially important, should also take two use double insurance.
Economy:
It chooses one of the dimensions, but must be economical on the basis of safety, applicability and reliability.
Economy is not only about the price of a product, but also about its function and quality, as well as the cost of installation, maintenance and other accessories.
More importantly, a solenoid valve in the whole automatic control system in the whole automatic control system and even in the production line accounted for very little cost, if costed by small and cheap wrong selection and caused damage group is huge.
