Selection
Solenoid valve selection should be followed by guided security, reliability, applicability, economy four principles and six on-site condition requirements (ie, diameter size, media type, pressure level, supply voltage, action pattern, special functions).
four principles
一. Security: if not pay attention to security, it will lead to disaster!
1. Corrosive media: should use plastic solenoid valve and all stainless steel; for the strong corrosive medium must select isolated diaphragm. Such as CD-F. Z3CF. Neutral medium, it should use copper alloy for the shell material solenoid valve, otherwise the shell rust is often chip off, especially the infrequent acting occasions. Ammonia valve can not use copper.
2. Explosive environments: explosion-proof grade products must be selected accordingly, open-air installation or more dust occasions should use waterproof, dust-proof varieties.
3. Solenoid valve nominal pressure shall not exceed the pipe internal maximum working pressure.
二. Applicability: Not applicable means using money buy nothing, and also trouble!
1. medium characteristic
1.1 gas, liquid or mixed state select different kinds of solenoid valve, such as ZQDF for air, ZQDF-Y for liquid, ZQDF-2 (or -3) for the steam, otherwise easily to cause malfunction. ZDF Series multi-functional solenoid valve is common for the use of air, liquids. So please show the medium state when ordering, and the installing users will no longer debug.
1.2 Medium temperature are different with products specifications, otherwise the coil will be burnt, sealing piece will aging, seriously affect the service life.
1.3 medium viscosity, usually below 50cSt. If it exceeds this value, diameter of greater than 15mm uses ZDF Series multi-function solenoid valve to make a special order. Diameter of less than 15mm orders high viscosity solenoid valve.
1.4 when medium cleanliness is not high, before the media should be equipped with the solenoid valve backflushing filter, when pressure is low, we can choose straight diaphragm solenoid valve, for example, CD-P.
1.5 If the medium is directional flow and is not allowed backflux ZDF-N and ZQDF-N need to use a single two-way flow, please make a special request.
1.6 Medium temperature should be chosen within the allowable range of solenoid valve.
2. Pipeline Parameters
2.1 According to media flow requirements and pipe connection mode to select valve openings and model. For example, we select CA5 and Z3F used for a pipeline switches to the two channels, and the small diameter, medium or large diameter please select ZDF-Z1 / 2. Another example is control of convergence of the two pipelines, please select ZDF-Z2 / 1 and so on.
2.2 In accordance with the value of the selected flow rate and valve Kv DN, but also optional with the pipe diameter. Please note that some manufacturers are not marked with the Kv value, often less than the interface valve hole size diameter, must not covet low price and makes a botch.
2.3 working pressure differential
Minimum working pressure differential above 0.04Mpa can be selected indirect pilot type; minimum working pressure differential close to or less than zero must be selected direct-acting type or sub-step direct type.
3. Environmental conditions
3.1 the maximum and minimum environment temperature should be chosen within the allowable range, if exceed the differential should be needed to show as a special order.
3.2 relative environment humidity is high and there are water droplets and rain and so on, should be selected water-proof solenoid valve.
3.3 Environment often had vibration, bumps and shocks and other occasions should be selected special varieties such as marine solenoid valve.
3.4 Used in a corrosive or explosive environments, it should be given priority to select corrosive-resistant according to the safe requirements.
3.5 if environmental space is limited, please use multi-functional solenoid valve, because it eliminates the need for a bypass, and three manual valves, so it is easy for online maintenance.
4. Power Supply Conditions
4.1 according to power supply types, selecting AC and DC solenoid valves separately. Generally speaking, it is convenient to use AC power.
4.2 Voltage specification with the best preferred to AC220V.DC24V.
4.3 power supply voltage fluctuations, AC is usually chosen +10% .- 15%, DC is almost allowed to ±% 10, if over differential, we should take stabilivolt measures or make special order requests.
4.4 The rated current and power consumption should be based on rated power capacity. it should be noted that the VA value is higher when AC starts, inadequate capacity should be preferred to select the indirect-guided solenoid valve.
5. Control precision
5.1 Common solenoid valve only has open, closed two locations, when in the control of high precision and parameters need smooth , please select mult-position solenoid valves; Z3CF three-position normal open solenoid valve, with low lift, full open and close three kinds of flows;
ZDF-Z1/1 combined multi-functional solenoid valve has a full open, wide open, small open, full open four kinds of flows.
5.2 Action Time: refers to connect or disconnect the electrical signal to the main valve movement completion time, and only our company's patented multi-functional solenoid valve can adjust the opening and closing time, it is not only to meet the control accuracy requirements, but also to prevent water hammer damage.
三、 Reliability: unreliable would damage the entire system!
1、 working life, this is not included in leave factory test project, belonging to type test project. In order to ensure quality, you should select brand-name manufacturers.
2、 the working standard: long-term system, repeated short-term work system and short-term work system three kinds. Our company's conventional products are long-term work system, in which the work coil to allow long-term electricity. For the valve opens a long time but only with a short-term closure case, it is suitable to select normal open solenoid valve. When used in short-term work system and with large quantities, they can be used as a special order to reduce power consumption.
3、 the working frequency: when action frequency requests is high, the structure should be preferred to select direct drive type solenoid valve, the power should be selected the AC.
4、 operating reliability
Strictly speaking, this test project has not been yet formally included in our solenoid valve professional standards, to ensure the quality it is needed to choose the brand-name manufacturers. the number of actions in some occasions are not many, but with very high reliability requirements, such as fire protection, emergency protection, must not be taken lightly. Particularly important, we should use in conjunction to take two pairs of insurance.
四. Economy: without economy is a waste of money, energy and even life
It is one of the chosen scale, but it must be the economy based on a safe, suitable and reliable.
Economy is not only the product price, but also to give priority to their functions and quality, as well as the installation and maintenance, and other accessories required cost.
More important, the share of the cost of a solenoid valve in the entire self-controlled systems throughout the entire production line is very little, if just for the sake of small cheap and the wrong group of selected damage is enormous.
Six on-site condition requirements
1、 according to the pipe parameters to choose solenoid valve: diameter specifications (ie, DN), interface mode (connection mode)
（1） In accordance with on-site piping diameter size or flow requirements to determine the diameter (DN) size.
（2） interface mode, generally DN> 65 should be selected flange interface, DN ≤ 65 can be according to the user requests to choose threaded or flanged type
2、 According to media type to select solenoid valve: the body materials, sealing materials, the temperature group
（1） Corrosive Fluid: Body material should use stainless steel or PTFE (polytetrafluoroethylene, commonly known as plastic king), and the optional fluorine rubber or PTFE sealing material.
（2） The edible or ultra-clean fluids: Body material should use sanitary stainless steel, and matching silicone rubber sealing material.
（3） high-temperature fluids: To choose high temperature resistant electrical materials and sealing materials solenoid valve, but also to choose the structure of piston-type principles.
（4） fluid status: ranging from a gaseous, liquid or mixed state, especially when the diameter is greater than 25 must be separate because it has something to do with guided hole parameters.
（5） Fluid Viscosity: usually below 50cSt t can arbitrary choose, if it exceeds this value, it would take choice of high-viscosity solenoid valve.
（6） fluid cleanliness: when medium contain impurities, before the solenoid valve we should install the filter and other optional structures.
3、 according to the pressure grade to select solenoid valve principle, structural type
（1） When the solenoid valve takes a long time to start, and continuous opening time is much longer than the closing time, should use normal open type.
（2） If the frequent switching on and off or short open time, or the open and closed time is almost the same, then select normally closed type.
（3） but there are some conditions for security protection, such as the furnace flame monitoring, gas leak alarm, fire safety linkage system, you should choose an emergency cut off solenoid valve instead of a long-term power-on selection (long-term power is only a relative concept), it is also not allowed to choose normal open type.
（4） self-holding type solenoid valve (also known as: Bi-stable) is a new technology, it is mainly used for the need of conserving energy or low-voltage drive occasions.
4、 Supply voltage options: try to give priority to select a common AC220V, DC24V which is more convenient.
5、 according to the length of working hours or special need to select the control mode: normally closed, normally open type, self-sustaining, emergency cut-off type (manual reset)
（1） Nominal pressure: This parameter is the same with other common valves meaning, is based on the pipe nominal pressure or 1.5 times of the using pressure to decide.
（2） Working pressure differential: refers to when the solenoid valve is in closed or open state, the value that the front-end pipeline pressure subtracts back-end pipeline pressure; when no pressure differential, low pressure differential, vacuum, we must use direct action type or sub-step direct-action principle; when with a certain pressure, the various principles of structural forms can be selected.
6、 According to the environmental requirements to select auxiliary functions: explosion-proof, check, manual, water fog, water-pouring, diving
（1） flammable and explosive environment: must choose the appropriate level of explosion-proof solenoid valves (our company's existing: EXDⅡCT5)
（2） When the pipes media has backflow phenomenon, choose our ZC series solenoid valve with check function.
（3） When need on-site manual operation for solenoid valve, choose our ZCA / B series solenoid valve with manual features.
（4） The open-air installation or dust multiple occasions should use waterproof, dust-proof varieties (the protection grade is above IP45). For the fountain, or diving underwater pipeline, it is necessary to adopt driving solenoid valve (the protection grade is above IP68).
