Pressure Test, Evacuation And Dehydration - Toshiba MAR-C104M8-1-PE Service Manual

11. PRESSURE TEST, EVACUATION AND DEHYDRATION

When Multi controllers are delivered from the factory the PMV's are in the fully open position. After power is
supplied to the system the PMV's assume their required operating position, including closed. Before
performing the pressure test or evacuation ensure that all Multi controller PMV's are in the fully open
position as shown in the "Manual operation of valves" (10.5).
11.1 Precautions for R407C Systems
• R407C outdoor units use synthetic oils which are extremely hygroscopic. Therefore ensure that the
refrigerant system is NEVER exposed to air or any form of moisture.
• Mineral oils are unsuitable for use in these units and may lead to premature system failure.
• Use only equipment which is suitable for use with R407C. Never use equipment which has been
used with R22.
• R407C should only be charged from the service cylinder in the liquid phase. It is advisable to use a
gauge manifold set equipped with a liquid sight glass fitted in the centre (entry) port.
11.2 Pressure test.
• Supply oxygen free nitrogen (OFN) gas at a pressure of 30kgf/cm
suction gas side service valve.
11.3 Evacuation and Dehydration.
• When removing air and dehydrating refrigerant pipe work use an approved type of vacuum pump,
do NOT use refrigerant to purge the air.
2-Pipe evacuation positions:
3-Pipe evacuation positions:
(Refer to diagrams below).
• Ensure to create a vacuum of -76cmHg at both the Liquid and Gas sides.
2-Pipe
Charge port
3-Pipe
Charge ports
Packed valves
Liquid pipe
Gas pipe
Liquid pipe
Discharge
gas pipe
Liquid pipe and Gas pipe charge ports.
Liquid pipe and Discharge gas pipe charge ports.
Service valve
Service valve
Suction gas pipe
59
2 G to the charge port on the