Solenoid valve selection

1. Economical
There are many solenoid valves that can be used in general. In the process of selection, the most economical product should be selected, but it must be economical on the basis of safety, application and reliability. Economy is not only the price of the product, but also its function and quality, as well as the cost of installation, maintenance and other accessories. More importantly, the cost of a solenoid valve in the entire automatic control system and even in the production line is very small. If it is greedy for small and cheap and wrongly selected, it will cause huge damage. In a word, economy not only refers to product price, but also product performance-price ratio to comprehensive cost-price ratio.

2. Security
(1) Corrosive medium: plastic king solenoid valve and all stainless steel should be used; for strong corrosive medium, isolation diaphragm type must be used. For neutral medium, it is also advisable to use a solenoid valve with copper alloy as the valve casing material, otherwise, rust chips often fall off in the valve casing, especially in the occasions where the action is not frequent. Ammonia valves cannot be made of copper.
(2) Explosive environment: Products with corresponding explosion-proof grades must be selected, and waterproof and dust-proof varieties should be selected for outdoor installation or in dusty occasions.
(3) The nominal pressure of the solenoid valve should exceed the maximum working pressure in the pipe.

3. Reliability
1. Working life, this item is not included in the factory test item, but belongs to the type test item. In order to ensure the quality, brand-name products from regular manufacturers should be selected.
2. Work system: There are three types of long-term work system, repeated short-time work system and short-time work system. For the case where the valve is opened for a long time and only closed for a short time, a normally open solenoid valve should be used. When used in short-time working system and large batches, special orders can be made to reduce power consumption.
3. Operating frequency: When the operating frequency is required to be high, the structure should preferably be a direct-acting solenoid valve, and the power supply should preferably be AC.
4. Action reliability: Strictly speaking, this test has not been officially included in the professional standards of my country's solenoid valves. In order to ensure the quality, brand-name products from regular manufacturers should be selected. In some occasions, the number of actions is not many, but the reliability requirements are very high, such as fire protection, emergency protection, etc., must not be taken lightly. It is especially important to take two consecutive double insurances.

4. Applicability
1. Medium characteristics
1.1 Choose different types of solenoid valves for gas quality, liquid state or mixed state. It is best to inform the medium state when ordering, so that the installation user does not need to adjust the mode.
1.2 The medium temperature is different for products of different specifications, otherwise the coil will burn out and the seals will be aged, which will seriously affect the service life.
1.3 Medium viscosity, usually below 50cSt. If it exceeds this value, the ZDF series multi-function solenoid valve should be used for special order if the diameter is larger than 15mm. The diameter is less than 15mm to order high viscosity solenoid valve.
1.4 When the cleanliness of the medium is not high, a recoil filter valve should be installed in front of the solenoid valve. When the pressure is low, a direct-acting diaphragm solenoid valve can be used.
1.5 If the medium is in directional circulation, and reverse flow is not allowed, ZDF-N and ZQDF-N only need to use bidirectional circulation, please make special requirements.
1.6 The medium temperature should be selected within the allowable range of the solenoid valve.

2. Pipeline parameters
2.1 Select the valve diameter and model according to the medium flow direction requirements and the pipeline connection method.
2.2 Select the nominal diameter according to the flow rate and Kv value of the valve, or the same as the inner diameter of the pipeline.
2.3 Working pressure difference, indirect pilot type can be used when the minimum working pressure difference is above 0.04Mpa; direct-acting type or step-by-step direct type must be used when the minimum working pressure difference is close to or less than zero.

3. Environmental conditions
3.1 The maximum and minimum temperature of the environment should be selected within the allowable range. If there is any excess, a special order should be made.
3.2 When the relative humidity in the environment is high and there is water droplets and rain, the waterproof solenoid valve should be selected.
3.3 There are often vibrations, bumps and shocks in the environment, and special varieties should be selected, such as marine solenoid valves.
3.4 For use in corrosive or explosive environments, corrosion resistance should be selected first according to safety requirements
3.5 If the environment space is limited, please choose a multi-function solenoid valve, because it saves the bypass and three manual valves and is easy to maintain online.

4. Power Conditions
4.1 According to the type of power supply, select AC and DC solenoid valves respectively. Generally speaking, AC power is easy to use.
4.2 AC220V.DC24V should be preferred for voltage specification.
4.3 The power supply voltage fluctuation is usually +%10%.-15% for AC, and ±%10 for DC is allowed. If it is out of tolerance, voltage stabilization measures must be taken or special order requirements must be put forward.
4.4 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 during AC starting, and the indirect pilot solenoid valve should be preferred when the capacity is insufficient.

5. Control accuracy
5.1 Ordinary solenoid valves only have two positions: open and close. When the control accuracy is high and the parameters are required to be stable, please choose a multi-position solenoid valve; -Z1/1 combined multi-function solenoid valve has four flow rates: full open, wide open, small open and full open.
5.2 Action time: refers to the time from when the electrical signal is turned on or off to the completion of the main valve action. Only the multi-function solenoid valve patented by our company can adjust the opening and closing time respectively, which can not only meet the requirements of control accuracy, but also prevent water hammer damage.

5.3 Leakage
The leakage value generally given on the sample is a common economic grade. If it is too high, please make a special order.