I. safety: if we do not pay attention to safety, disaster will happen.
1. Corrosive medium: Plastic King solenoid valve and stainless steel should be selected; isolation diaphragm type should be selected for the strongly corrosive medium of imported water solenoid valve. In neutral medium, the solenoid valve with copper alloy as shell material should also be selected. Otherwise, rust debris often falls off from the valve shell, especially when the action is not frequent. Ammonia valves cannot be made of copper.
2. Explosive environment: the corresponding explosion-proof grade products must be selected. Waterproof and dust-proof varieties should be selected for outdoor installation or dust-proof occasions.
3. the nominal pressure of solenoid valve should exceed the maximum working pressure in the pipe.
Two. Applicability: does not apply to equal to spend money to buy things, but also add trouble!
1. dielectric properties
1.1 Imported explosion-proof solenoid valve quality gas, liquid or mixed state respectively choose different types of solenoid valve, for example, ZQDF for air, ZQDF-Y for liquid, ZQDF-2 (or-3) for steam, otherwise easy to cause misoperation. ZDF series multi-function solenoid valves can be connected to gas. Liquid. It is best to specify the state of the media when the time is set.
1.2 For products with different dielectric temperatures and specifications, imported ultra-high temperature solenoid valves will burn out the coils and aging the seals, which will seriously affect the life of the products.
1.3 medium viscosity, usually below 50cSt. If the value exceeds this value, the diameter is greater than 15mm, and the ZDF series multi-function solenoid valve is used for special orders. The diameter is less than 15mm, high viscosity solenoid valve is set.
1.4 When the cleanliness of the medium is not high, the backwash filter valve should be installed in front of the solenoid valve. In low pressure fashion, the direct diaphragm solenoid valve can be used as an example, CD-P.
1.5 If the medium is directionally flowing, and ZDF-N and ZQDF-N are not allowed to flow backwards only in two directions, please make special requests.
1.6 medium temperature of imported ultra high temperature solenoid valve should be selected in the allowable range of solenoid valve.
2. pipe parameters
2.1 select the valve port and type according to the requirement of media flow and the way of pipe connection. For example, for switching one pipe to two pipes, CA5 and Z3F for small diameter, ZDF-Z1/2 for medium or large diameter. If you want to control the convergence of two pipes, please select ZDF Z2/1.
2.2 according to the flow and valve Kv value, the nominal diameter can be selected, and the inner diameter of the pipe can also be selected. Please note that some manufacturers have not marked the Kv value, often the size of the valve hole is smaller than the diameter of the interface pipe, must not be greedy for low prices and errors.
2.3 import high pressure explosion proof solenoid valve working pressure difference
The indirect pilot type can be selected when the minimum working pressure difference is above 0.04 Mpa; the direct or step-by-step direct type must be selected when the minimum working pressure difference is close to or less than zero.
3. environmental conditions
3.1 The highest and lowest temperatures of the environment should be within the allowable range, and special orders should be made if there is an overshoot.
3.2 Waterproof solenoid valves should be selected for high relative humidity and raindrops in the environment of imported ultra-high voltage solenoid valves.
3.3 in the environment, special varieties, such as marine solenoid valves, should be selected for occasions such as vibration, bump and impact.
3.4 use in corrosive or explosive environments should be preferred according to safety requirements.
3.5 If the environment space is limited, please choose multi-functional solenoid valve, because it saves bypass and three manual valves and is convenient for online maintenance.
4. power conditions
4.1 import zero voltage differential solenoid valve, according to the type of power supply, choose AC and DC solenoid valves respectively. Generally speaking, AC power supply is easy to use.
4.2 voltage specification should try to give priority to AC220V.DC24V.
4.3 Voltage fluctuation of power supply is usually selected as% 10%. -15% AC, and DC is allowed to be around (% 10). In case of overshoot, voltage stabilization measures or special order requirements must be taken.
4.4, rated current should be selected according to the power supply capacity.
And power consumption. It should be noted that the VA value is higher when AC starts, and the indirect guided solenoid valve should be preferred when the capacity is insufficient.
5. control accuracy
5.1 Ordinary solenoid valves have only two positions of opening and closing. When the control accuracy and parameters are required to be stable, please choose multi-position solenoid valves; Z3CF three-position open solenoid valves have three flow rates: micro-opening, full-opening and closed.
ZDF Z1/1 combined multi-function solenoid valve has four kinds of flow: full open, wide open, small open and full open.
5.2 Operation time: refers to the time when the electrical signal is connected or cut off to the main valve. Only the multi-function solenoid valve of our company can adjust the opening and closing time separately, which can not only meet the control accuracy requirements, but also prevent water hammer damage.
Three. Reliability: unreliability will damage the whole system!
1. Working life. This item is not included in the ex-factory test item. The imported flange solenoid valve belongs to the type test item. In order to ensure the quality, we should choose the famous brand products of regular manufacturers.
2, work standard: divided into long term work system, repeated short time work system and short time work system three kinds. The company's regular products are long term work, that is, the coil allows long-term power. The imported flange solenoid valve is suitable for the case that the valve is opened for a long time and closed only for a short time. It can be used for special orders to reduce power consumption when short working hours are large.
3. Working frequency: When the operating frequency is high, the structure should be preferred to import direct-acting solenoid valves, and the power supply should be preferred to listen to and communicate.
4. Motion reliability
Strictly speaking, this test has not yet been formally included in the professional standards of solenoid valves in China. In order to ensure the quality, we should choose the famous brand products from the regular manufacturers. In some occasions, the number of actions is not much, but the reliability requirements are very high, such as fire protection, emergency protection, etc., must not be taken lightly. In particular, two double insurance should be adopted.
Four. Economy: the import of stainless steel solenoid valves is not economical, which is a waste of money, energy and even life.
It is one of the yardstick of choice, but it must be an economy based on safety, applicability and reliability.
Economy is not only the price of the product, but also the function and quality of the product, as well as the cost of installation, maintenance and other accessories.
More importantly, the cost of a solenoid valve in the whole automatic control system and even in the production line is negligible, and the damage caused by greedy and cheap misselection is huge.
