Parker® LAC-4-DS180 ERP_073978

The valve designation LAC stands for low ambient control. The LAC-4 is a 3-way modulating valve that responds to discharge pressure. As shown in figures 1 and 2, the discharge pressure bleeds around the pushrod to the underside of the diaphragm. The discharge pressure opposes the dome pressure. When the outdoor ambient falls, the condensing pressure falls. This causes the discharge pressure to fall as well. When the discharge pressure falls below the dome pressure, the valve modulates open to the discharge port which allows discharge gas to bypass the condenser. Mixing the discharge gas with the liquid creates a high pressure at the condenser outlet, reducing the flow and causing liquid to back up in the condenser. Flooding the condenser reduces the area available for condensing. This reduction in effective condenser surface area results in a rise in condensing pressure. During summer conditions, the discharge pressure is high thus closing the discharge port. Hence, there is full liquid flow from the condenser to the receiver.

Parker® LAC Head Pressure Control Valve, 1/2 in Nominal, ODF Connection, 3 -Port/Way, 180 lb/sq-in Pressure, Steel Element, 6.11 in H x 1.94 in Dia

• Dual setting (omit for standard dome element)

• Catalog https://assets.unilogcorp.com/267/ITEM/DOC/Parker_LAC_4_DS180_Catalog.pdf