Toshiba HFC R407C, Service Manual

Page: 69 / 80

69
Refrigerant pipe installation
Leak test
Airtight test
Carry out an airtight test after the refrigerant piping is complete. For an airtight test, connect a nitrogen
gas bottle as shown, and apply pressure (use oxygen-free nitrogen, OFN).
The pressure test must be completed before supplying power to ensure that the Multi Controller PMVs
(pulse modulating valves) are open.
The test must be completed with the indoor units, Multi Controllers and outdoor unit connected.
• Be sure to carry out the test from the service ports of the packed valves at the discharge gas,
liquid and suction gas side.
• Keep all of the valves at discharge gas, liquid and suction gas sides fully closed. Nitrogen may
enter the cycle of the outdoor unit. Therefore, retighten the valve rod before applying pressure.
(For all valves.)
• For each refrigerant line, apply pressure gradually at the discharge gas, liquid and suction gas
sides.
Never use oxygen, or a flammable noxious gas.
Low
pressure
gauge High
pressure
gauge
Packed valve fully closed
(gas suction side)
Inverter outdoor unit
Gauge
manifold
Brazed
Service port
Copper
pipe
ø 6.4
Regulator
Nitrogen
gas
Service port
Flare
connection
Flare
connection
Packed valve fully
closed (liquid side)
Packed valve fully closed
(gas discharge side)
To detect a large leakage
Step 1: 0.3 MPa (3 kg/cm
2
G) Apply pressure for 3 minutes or more
Step 2: 1.5 MPa (15 kg/cm
2
G) Apply pressure for 3 minutes or more
To detect a fine leakage
Step 3: 3.0 MPa (30 kg/cm
2 G) Apply pressure for 24 hours
• Check for a reduction in pressure.
If there is no reduction in pressure this is acceptable.
If there is a reduction in pressure check for a leakage.
(Note: If there is a difference of ambient temp. between when the pressure was applied and 24 hours later,
then pressure could change by approx. 0.01 MPa (0.1 kg/cm
2
G) - so correct the pressure change.
Service port at gas
discharge side
Service port at
liquid side
Service port at
gas suction side
To
manifold
Detailed drawing of packed valve
Copper
pipe
ø 6.4