How to Select a Solenoid Valve for Chemicals
Selection of the right solenoid valve for chemicals implies a thorough evaluation of process medium, operating conditions and system requirements.
1.What is the chemical medium? What is the exact chemical name? What is the concentration? What is the purity? What else is in there? Compatibility properties can differ according to the concentration of the same chemical. Refer to the chemical resistance chart, which is provided by the manufacturer.
2.Use the right materials. Check valve body, internal parts, seals and gaskets. Such materials as stainless steel, PTFE, EPDM, FKM have different limits of chemical resistance. There is no material suitable for all chemicals. Verify chemical resistance at actual operating temperature and concentration.
3.Verify pressure and temperature. Calculate the minimum, normal and maximum operating pressure and temperature. Keep the valve and the seals within their limits. For pilot operated designs, verify the minimum differential for operation.
4.Determine flow requirements. Calculate required flow rate and allowed pressure drop. Check flow coefficient, port size and working range of the valve. Inappropriate valve sizing leads to improper dosing or unsatisfactory flow performance.
5.Select the proper operating configuration. Select normally closed or normally open according to the default state desired. Verify that system pressure and flow requirements match direct acting or pilot operated design.
6.Check electrical specifications. Check AC/DC voltage, power consumption, coil duty rating, electrical connector and environmental protection.
7.Check connections and installation. Standard of thread or flange, direction of flow, installation orientation, and available space.
8.Evaluate safety and maintenance needs. Consider requirements for leakage, risks of chemical exposure, cleaning procedures, replacement parts and accessibility of maintenance. Specialized equipment or certifications may be required for hazardous chemicals applications.
Finally, ask for technical drawings, pressure and temperature ratings, chemical compatibility and relevant test results. Choosing the right valve can help to increase dosing accuracy, equipment reliability, chemical handling safety and reduce premature failure and maintenance costs.
Advice for Avoiding Common Mistakes in Chemical Solenoid Valve Design
1.Do not assume universal chemical resistance. Identify precise medium, concentration, temperature and exposure conditions.
2.And do not forget about seal compatibility. Even though the body is compatible with the metal does not mean that the seals are not going to suffer.
3.Do not over-size or under-size the valve. Do the calculation for flow rate and pressure differential, not for the pipe size.
4.Verify the operating pressure. Check that the valve will operate within minimum and maximum pressures of the system.
5.Choose the right valve gear. Pilot operated and direct acting valves have different operating requirements.
6.Define the default valve position. Determine if the process requires a normally closed or normally open valve upon loss of power.
7.Verify the coil specifications. Match power supply, voltage, duty cycle and ambient temperature conditions.
8.Consider chemical leakage risks. Ensure the appropriate sealing performance. Provide proper containment where needed.
9.Check installation requirements. Pay attention to flow direction, mounting position and connection requirements.
- ย Maintenance schedule. Ensure inspection and cleaning and component replacement can be done safely.
