T-354 7–2Figure 7.2 Manifold Gauge SetA. Connection to Low Side of SystemB. Connection to either: Refrigerant Cylinder or Oil ContainerC. Connection to High Side of System- - - - -7.3 MANIFOLD GAUGE SETThe manifold gauge set (see Figure 7.2) is used to determine system operating pressure, add refrigerant charge,and to equalize or evacuate the system.When the suction pressure hand valve is frontseated (turned all the way in), the suction (low) pressure can bechecked. When the discharge pressure hand valve is frontseated, the discharge (high) pressure can be checked.When both valves are open (turned counter-clockwise all the way out), high pressure vapor will flow into the lowside. When the suction pressure valve is open and the discharge pressure valve shut, the system can be charged.Oil can also be added to the system.A R-134a manifold gauge/hose set with self-sealing hoses (see Figure 7.3) is required for service of the modelscovered within this manual. The manifold gauge/hose set is available from Carrier Transicold. (Carrier TransicoldP/N 07-00294-00, which includes items 1 through 6, Figure 7.3). To perform service using the manifold gauge/hose set, do the following:Preparing Manifold Gauge/Hose Set For UseIf the manifold gauge/hose set is new or was exposed to the atmosphere, it will need to be evacuated to removecontaminants and air as follows:1. Back seat (turn counterclockwise) both field service couplings (see Figure 7.3) and midseat both handvalves.2. Connect the yellow hose to a vacuum pump and refrigerant 134a cylinder.3. Evacuate to 10 inches of vacuum and then charge with R-134a to a slightly positive pressure of 0.1kg/cm(1.0psig).4. Front seat both manifold gauge set valves and dis connect from cylinder. The gauge set is now ready foruse.OPENED (Backseated )HAND VALVE CLOSED (Frontseated)HAND VALVESUCTIONPRESSUREGAUGEDISCHARGEPRESSUREGAUGEA B C
