Normally Open
- Compact size
- No disassembly necessary for soldering
Accessories
Actuation coil and cable assemblies available for various voltages, see ‘Coils ESC and Cable Assemblies’
Basic Terms and Technical Information Operating Principles
Directly actuated The magnetic field of the solenoid coil forces a movement of the plunger and thus causes the opening of the valve seat.
Actual pressure drop Nominal pressure drop at Qn1 Calculated nominalcapacity
Nominal capacity of selected valve
Servo actuated The magnetic field of the solenoid coil is only utilized for the opening of the pilot valve seat. The necessary energy to actuate the piston or diaphragm of the main valve seat is provided by the refrigerant flow and results in a certain pressure drop.
Minimum Pressure Drop
Directly actuated solenoid valves do not require a minimum pressure drop for proper operation.
Maximum Operating Pressure Differential (MOPD)
MOPD is the maximum pressure differential between inlet and outlet of the solenoid valve which permits proper opening of the valve. When used with Alco AC solenoid coils all Alco solenoid valves employ 25 bar MOPD.
Operation in conjunction with DC solenoid coils lead to reduced MOPD values depending on valve type and size. The DS2 Chopper Plugs allow the use of 24VAC coils with 24VDC by converting the DC in an AC voltage. Please contact Emerson application engineering for additionaldetails.
Servo operated solenoid valves require a minimum pressure drop of approximately 0.05 bar to remain fully open. In case of insufficent refrigerant flow, this value will not be reached and the solenoid valve may close unintentionally. These closures may lead to malfunctions and oscillations in the refrigeration circuit. Improper sizing of solenoid valves (i.e.,use of excessivelylarge solenoidvalves) is the main cause of this effect. This is particularly important in capacity controlled refrigerationcircuits.
Therefore the decisive factor for proper solenoid valve sizing is the respectivecapacity of the valve and not its connection size.
Formula for calculating the actual pressure drop of a solenoid valve
