Vilter VSM 71-701 Operation And Service Manual Download

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HA4AOAS - Inlet/Outlet Economizer Port / Side Load Pressure

Regulator

Purpose:

To maintain an operating pressure in the economizer or side load vessel, while providing a means

of protecting the compressor motor from overloading from high economizer loads during start-up, or from
high side loads.

Construction:

This valve is made up of an Outlet Pressure Regulator Base, an Inlet Pressure Regulator

Module, and a Shut Off Solenoid.

Operation:

The Shut Off Solenoid must be energized to activate the HA4AOAS valve. For a flash type or

shell & coil type economizer, or for side load applications, the solenoid must be activated when the
compressor starts. For a direct expansion type, the solenoid is generally activated when the compressor
reaches 30% to 70% compressor capacity, depending on the system.

Adjusting the Inlet / Economizer or Side Load Pressure

The estimated economizer operating pressure of the valve will be as shown on the performance printout for
the compressor unit. Side load pressure settings would be set as required for the system. By means of a
pressure gauge, the actual economizer operating pressure can be determined by placing the Inlet Pressure
Regulator module range spring at minimum force (control module stem should be fully turned counter-
clockwise). Leaving the regulator in this position, the actual economizer compressor port pressure can be
read. NOTE: The compressor must be at 100% capacity and at normal operating suction and discharge
pressures before the actual port pressure can be determined. Once this pressure is known, the module stem
should be turned clockwise until there is a slight increase in pressure shown on the gauge. Increasing the
turns on the module stem will raise the inlet pressure.

Adjusting the Outlet / Maximum Port Pressure

The Outlet Pressure setting is a maximum pressure setting that will allow the compressor to load to 100%.
If too much economizer or side port gas flow occurs, port pressure increases resulting in a motor amperage
increase, which may result in amp limiting and the compressor will not load to 100%. In order to adjust the
Outlet Pressure Module, its range spring should be set near maximum force (control module stem should be
fully turned clockwise). If the compressor is not able to fully load because of Amp limiting, the outlet
pressure needs to be decreased by turning the stem counter-clockwise until there is a decrease in pressure
shown on the gauge. Reduce outlet pressure until motor amperage drops and the compressor is able to load
to 100% capacity. Make sure that the Outlet Pressure setting is at least 10 psig higher than the inlet pressure
to prevent a conflict in operation of the inlet and outlet features of the valve. NOTE: There must be
abnormally high gas flow to set the outlet feature. It may not be necessary to use the outlet feature if the
compressor motor has been sized large enough so that the unit does not amp limit on high economizer or
side load gas flow.

Vilter VSM 71-701, Operation And Service Manual

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