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Selecting the appropriate solenoid valve requires a comprehensive consideration of multiple key parameters and application scenarios. The following analysis is conducted from dimensions such as core parameters, medium characteristics, environmental conditions, and control requirements to help users precisely match their needs:
I. Define the core parameters
1. Diameter and flow requirements
Calculation method: Determine the diameter of the solenoid valve (DN value) based on the pipe diameter and the medium flow rate.
Example: If the inner diameter of the pipe is 25mm and the medium flow requirement is 10m3/h, an electromagnetic valve with a diameter of ≥DN25 should be selected to avoid excessive flow rate or pressure loss due to insufficient diameter.
CV value matching: Verify whether the solenoid valve meets the flow requirement by calculating the flow coefficient (CV value). The CV value represents the water flow rate (GPM) passing through the valve when it is fully open and the pressure difference is 1psi.
2. Pressure range
Working pressure: Ensure that the rated pressure of the solenoid valve (such as PN16, Class150) is higher than the maximum working pressure of the system and leaves a 20% safety margin.
Pressure resistance capacity: If the system experiences pressure fluctuations or water hammer phenomena, a solenoid valve with a higher pressure resistance grade should be selected (such as a design with an overpressure of 1.5 times).
3. Medium compatibility
Material selection:
Water/oil medium: Brass and stainless steel (304/316L) materials are selected.
Corrosive media: Select PTFE, PVC or Hastelloy seals according to the type of medium.
High-temperature medium: The temperature resistance range should cover the medium temperature (such as -40℃ to +200℃).
Viscosity influence: For high-viscosity media (such as ink, resin), direct-acting or pilot-operated solenoid valves should be selected to prevent the valve core from getting stuck due to medium retention.
Ii. Analyze the characteristics of the medium
1. Physical state
Gas/liquid: For gas media, solenoid valves with exhaust structures (such as vacuum solenoid valves) should be selected. For liquid media, attention should be paid to the anti-drip and leak-proof design.
Particle content: For media containing impurities, a filter (recommended to be 50 mesh or above) should be installed, or an electromagnetic valve with self-cleaning function should be selected.
2. Chemical properties
pH: For strong acid media (pH<2), PTFE or ceramic seals should be selected. For weak acid media (pH=4-6), EPDM rubber seals can be used.
Oxidizing property: For media with high chloride ion content, 304 stainless steel should be avoided and 316L or titanium alloy should be used instead.
Iii. Assess environmental conditions
1. Temperature range
Low-temperature environment: Below -20℃, anti-freezing type solenoid valves (with heating sleeves or specially designed for low-melting-point media) should be selected.
High-temperature environment: Above +80℃, high-temperature resistant coils (such as H-class insulation) and metal sealing structures should be adopted.
2. Protection level
Humid/dusty environment: Select IP65 or above protection grade to prevent coil short circuit or valve body rusting.
Explosive environment: Explosion-proof solenoid valves (such as ExdIICT4) should be selected and matched with the corresponding gas group.
3. Vibration and Shock
Vibration conditions: Select solenoid valves with anti-vibration design (such as adding spring buffer structures), or fix them with brackets to reduce the risk of resonance.
Iv. Determine the control mode
1. Driver type
Direct-acting type: Suitable for small diameter (DN≤15) and low pressure difference (≤0.1MPa) scenarios, with a short response time (<50ms).
Pilot type: Suitable for large diameter (DN≥20) and high pressure difference (≥0.5MPa) scenarios, it has low power consumption but requires a minimum starting pressure.
Step-by-step direct-acting type: Combining the advantages of both, it takes into account both low-voltage starting and high-voltage flow capabilities.
2. Power supply type
AC/DC selection:
AC220V: It has strong versatility, but a surge protector needs to be installed.
DC24V: High safety, suitable for explosion-proof or long-distance control.
Power consumption: Low-power solenoid valves (<5W) are suitable for battery-powered or solar systems.
3. Control signal
Switch type: Directly controlled on and off through a relay, suitable for simple start and stop scenarios.
Proportional type: Linear flow regulation is achieved by inputting a 4-20mA signal, suitable for precision metering systems.
V. Special Functional Requirements
1. Safety protection
Explosion-proof certification: The petrochemical industry must comply with ATEX or IECEx standards.
Overload protection: The solenoid valve with an internal thermal protector can prevent the coil from burning out.
2. Installation method
Space limitation: Compact solenoid valves (such as two-way cartridge valves) are suitable for integrated devices.
Direction requirement: Clearly mark the medium flow direction to avoid seal failure caused by reverse installation.
3. Maintenance requirements
Online maintenance: The modularly designed solenoid valve can have its coil or valve core replaced separately, reducing downtime.
Life index: Select a model with high reliability based on MTBF (Mean Time Between Failures) (such as industrial grade ≥ 500,000 times).
Vi. Summary of the Selection Process
Determine the basic parameters: diameter, pressure, medium and temperature