SA 3 134a - Sea Frost Refrigeration

CHANGING CANSThe compressor should be turned off while changing cans. Close the valve on theempty can. Unscrew the can from the valve body. Some pressure may be present. Letthis drop before completely removing the can tap. Switch the tap to the other can, andrethread onto the can.COMMISSIONING PROCEDUREEVACUATION WITH A VACUUM PUMPEvacuation removes air, readying the system for charging.Connect a gauge set to the service ports. Connect the gauge center hose to a highvacuum pump. Start the pump and slowly open the low side/suction gauge hand wheel.As the vacuum drops below 20 inches open both hand wheels fully.EVACUATION LEAK TESTEvacuate the system to the best vacuum (lowest pressure). As the gauge reaches thislow pressure close the valves to the pump. Observe the vacuum gauge and be sure thepressure remains constant for 5 minutes. If the pressure rises rapidly check all theconnections again. Re-evacuate to the lowest pressure and test by holding a vacuumwith the gauges closed. Be sure the system will hold this vacuum. Proceed by openingthe valves and continuing the evacuation process for 30 minutes more. A micron gaugecan be used to measure vacuum. Proper dehydration and evacuation should be on therange of 200 to 500 microns.The evacuation leak check is a preliminary check and is not to be considered a systemleak check.NEW SYSTEM CHARGINGINTRODUCING INITIAL CHARGEAfter the evacuation leak test and pump down, shut off the manifold valves, disconnectthe center hose from the pump and connect it to a can of refrigerant. Vent the hosefrom can tap (refrigerant supply) to the manifold. With the refrigerant can in the inverted(liquid) position, open the discharge side valve (high side) valve and feed in about a 1/2a can of refrigerant (6 to 8 ounces). Close the valve and begin an inspection of all theconnections in the system.21