Emerson 3000 Motorized Ball Valve-Digital Scroll Compressors, Manual Flushing, Control

Water-Cooled Models—Self-Contained Compressor

4.3.2High Pressure Valve - 350 psig (2413 kPa) System for 3-Ton Units (Metrex Valve) Adjustment

The valve may be adjusted using a 1/8" diameter rod. Turn the adjusting collar nut counterclockwise to raise head pressure; turn it clockwise to lower head pressure. Rotation directions are viewed from top of valve spring housing.

Figure 22 Metrex Valve adjustment

Adjusting collar nut

Table 12 Refrigerant control settings psi (kPa)

Low Pressure	Low Pressure	High Pressure
Cut Out	Cut In	Cut Out
20 (137.9)	65 (448.2)	400 (2758)

Manual Flushing

The valve may be flushed by rotating the socket head screw clockwise. This screw must be in the OUT position (counterclockwise) for normal valve operation.

4.4Motorized Ball Valve—Digital Scroll Compressors

On digital scroll units, discharge pressure is controlled by a motorized ball valve. During unloaded operation, the pressure changes during each digital cycle could cause excessive repositions with a pressure-operated water regulating valve. The control algorithm for the motorized ball valve uses an intelligent sampling rate and adjustable pressure thresholds to reduce valve repositions. The valve assembly consists of the brass valve, linkage and actuator.

4.4.1Control

The valve actuator operates on 24VAC power and is controlled by a 2-10VDC proportional control signal. The valve will move from fully open to fully closed in 60 seconds. At 2VDC, the valve is closed; at 10VDC, the valve is fully open. There is a 20-second delay to position the motorized ball valve before starting the compressor.

Liebert® Challenger 3000™ 40