Toshiba A90-0132, Service Manual

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17
Refrigerant pipe installation
Leak test
[1] Leak test pressure
For Multi Modular System air conditioner systems: 3.0MPa (30kg/cm 2 G)
[2] Test method
Supply oxygen free nitrogen (OFN) gas to the system as described.
•
The gas-side, liquid-side and balance valves must all be fully closed.
Note that there is a possibility that the nitrogen gas could become mixed into the outdoor unit cycle. Therefore, re-
tighten the valves (gas-side, liquid-side and balance) before applying pressure.
CAUTION:
Never use oxygen, a flammable gas, or a toxic gas for leak tests.
Apply pressure gradually in the prescribed steps for the gas, liquid and the balance sides for each individual refrigerant
system.
Ensure pressure is applied.
STEP 1 :
0.3MPa (3.0kg/cm 2 G) Apply pressure for at least 3 minutes.
STEP 2 :
1.5MPa (15.0kg/cm
2
G) Apply pressure for at least 3 minutes.
STEP 3 :
3.0MPa (30.0kg/cm
2
G) Apply pressure for 24 hours. This step permits detection of slow leaks.
Check for any loss of pressure. No loss of pressure: Pass
Loss of pressure: Check for location of leak
(Ensure you allow for any change in ambient temperature when the pressure was initially applied and the temperature 24
hours later. The pressure will change by approx. 0.01MPa (0.1kg/cm
2 G) per 1°C.)
NOTES:
If piping is long, an airtight test is performed for each divided block.
1) Indoor side + vertical pipe 2) Indoor side + vertical pipe + outdoor side
[3] Leaked position check
When a reduction in pressure is detected in STEPS 1 to 3, check for leakage at connecting points. Check leakage with
foaming agent, etc., and perform re-brazing or re-tightening of flare if leakage is detected.
Connected to indoor unit
Low
pressure
gauge High
pressure
gauge
Packed valve fully
closed (gas side)
Inverter outdoor unit
Main pipe
Gauge
manifold
Detailed drawing of packed valve
To gauge manifold
{
Gas-side
service port
Liquid-side
service port
Liquid-side
packed valve
Gas-side
packed valve
To main
unit
To main
unit
Piping at site
Piping at site
Piping at site
To main unit
Balance
service port
Balance
packed valve
Connected to other fixed-speed outdoor unit
Brazed
Service
port
Copper
pipe
∅
6.4
Copper
pipe
∅
6.4
Reducing
valve
Nitrogen gas
Service port
Fully closed
Fully closed
Packed valve fully
closed (liquid side)
Packed valve fully
closed (balance)