Service manual

112
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.
Detailed drawing of packed valve
To gauge manifold
{
Liquid-side
service port
Liquid-side
packed valve
Balance
service port
Balance
packed valve
Piping
at site
Gas-side
service port
Gas-side
packed valve
Piping at site
Piping
at site
To main unit
To main
unit
To main
unit
Connected to Indoor Unit
Connected to other fixed-speed Outdoor Unit
Packed valve fully
closed (liquid side)
Packed valve fully
closed (balance)
Inverter Outdoor Unit
Service
port
Service port
Gauge
manifold
Nitrogen
gas
Reducing
valve
Ø6.4
Copper
pipe
Ø6.4
Copper
pipe
Packed valve fully
closed (gas side)
Fully
closed
Fully
closed
Brazed
Low-
pressure
gauge
High-
pressure
gauge
Main pipe
V
L VH