User Guide

12
Solenoid valves are rated in terms of maximum operating-pressure differential
(MOPD) against which the valves will open.
Introduction
With the solenoid valve closed against an inlet pressure of 250 pounds-
per-square-inch gauge (psig) and outlet pressure of 50 psig, the pressure
differential is 250 minus 50, or 200 pounds per square inch (psi).
Example
The MOPD rating of the valve must be equal to or greater than 200 psi, if the
valve is to open properly.
Rating for proper operation
The temperature of the coil windings and the actual applied voltage are prime
factors affecting the MOPD rating. The MOPD is reduced as the coil temperature
increases or the applied voltage is lowered.
The MOPD ratings listed in solenoid manufacturers’ catalogs are determined
by operating the valve with 85 percent of rated coil voltage applied to the
coil after the solenoid coil has attained its maximum temperature under full
rated voltage.
Factors affecting rating
Although the solenoid valve’s primary function within refrigeration systems –
turning refrigerant flow on and off – seems simple enough, this function can
be quite complex and is essential in terms of ensuring correct installation,
service and benefits.
Solenoid valves in
refrigeration systems
The solenoid valve is a vital component in any refrigeration system. Knowing
how it works helps to ensure system benefits, such as energy efficiency, leak
prevention and overall system protection.
Ensuring refrigeration-
system benefits
Knowing how the solenoid valve works increases the likelihood that
contractors will install the valves correctly and in a way that ensures optimum
system performance.
This information will also aid service technicians who may have to remove the
valves to service the system, allowing them to correctly do so and then protect
the system by correctly reinstalling the valves.
Ensuring correct
installation and service
Maximum operating-pressure differential
Conclusion