To obtain reliable performance with solenoid valves on refrigeration or air conditioning systems, it demands careful consideration of application requirements during the selection process. Parker Sporlan offers a wide variety of solenoid valve sizes and styles which may be employed in refrigeration and air conditioning systems to electrically control refrigerant flow. Solenoid valves are electrically operated ‘stop-valves’. These are either fully open or fully closed. Remember these do not modulate flow.
Solenoid valves are typically classified according to the stem and plunger action.
A pilot operated valve makes use of pressure differential across the valve to allow for higher flow capacities without the need of a large solenoid coil. A minimum of 1 psi pressure differential is required to allow the disc/piston/diaphragm to return to its normal position. This is THE key statement, without a minimum pressure drop across the valve, once in operation the main port will not return to normal.
There has always been a tendency in the industry to select solenoid valves based on line size. However, due to the pressure drop required for proper operation, this policy is risky and not recommended.
In other words, if a liquid line solenoid valve is being selected for a system having 5/8-inch OD liquid line, there is a tendency to select any valve having 5/8 ODF connections. For example, we have 4 valve series with 5/8 OD connection sizes ranging from 6.0 tons to 23 tons. If a capacity of 15 tons is required, choosing solely based on line size can lead to detrimental scenarios.
Choose solenoid valve based on system capacity with a minimum of 1 psi pressure drop. Then choose from available connection sizes. If the desired connection sizes are unavailable, bushings and couplings can be used to adapt to the existing line size, which will NOT affect valve performance.
Example: 15 ton, R410A, Liquid Line Solenoid valve with 5/8 OD connections:
In this example, the E14 would be the best option. The reason is the load on the system may drop thus causing a marginally sized valve to be too big.
Article contributed by Henry Papa, sales engineer, Sporlan Division of Parker Hannifin.
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