Toshiba MCY-MUG0401HSW-E Installation Manual page 33

 Airtight test
Before starting an airtight test, further tighten the spindle valves on the gas side and liquid side.
Pressurize the pipe with nitrogen gas charged from the service port to the design pressure to conduct the airtight
test.
After the airtight test is completed, evacuate the nitrogen gas.
• Apply pressure from the service ports of the packed valves at liquid side and gas side.
• An air tight test can be only performed to the service ports at liquid side and gas side of the outdoor unit.
• Close fully valves at liquid side and gas side. As there is possibility that nitrogen gas enters in the refrigerant
cycle, re-tighten the valve rods before applying pressure.
• For each refrigerant line, apply pressure gradually with steps at liquid side and gas side.
Apply pressure to liquid side and gas side.
REQUIREMENT
Do not use "Oxygen", "Flammable gas" and "Noxious gas" in an airtight test.
Connected to indoor unit
Packed valve fully closed
Main pipe
(gas side)
Fully closed
Fully closed
To detect a gross leakage
1. Apply pressure 0.3 MPa (3.0 kg / cm 2 G) for 3 minutes or more.
2. Apply pressure 1.5 MPa (15 kg / cm 2 G) for 3 minutes or more.
To detect a slow leakage
3. Apply pressure 4.15 MPa (42.3 kg / cm G) for approx. 24 hours.
2
• Check pressure down.
No pressure down: Accepted
Pressure down: Check the leaked position.
NOTE
However, if the environmental temperature changes from the moment of applying pressure to 24 hours after that, the
pressure will change by about 0.01 MPa (0.1 kg / cm²G) per 1 °C. Consider the pressure change when checking the
test result.
REQUIREMENT
When pressure decrease is detected in steps 1-3, check the leakage at the connecting points.
Check the leakage using a foaming agent or other measures and seal the leak with re-brazing, flare retightening or other
methods. After sealing, execute an airtight test again.
63-EN
High pressure
Low pressure
gauge gauge
V V
L H
Gauge
Outdoor unit
manifold
Reducing
valve
Ø6.4
Service port
Copper pipe
Ø6.4
Copper pipe
Service port
Packed valve fully closed
(liquid side)
Nitrogen gas
 Air purge
NOTE
For the air purge at installation time (Discharge of air in connecting pipes), use "Vacuum pump method" from viewpoint
of the protection of the earths environment.
• For protection of the earths environment, do not discharge the refrigerant gas in the air.
• Eliminate the remaining air (nitrogen gas, etc.) in the unit by using a vacuum pump.
If gas remains, performance and reliability of the unit may be reduced.
After the airtight test, discharge nitrogen gas. Then connect the gauge manifold to the service ports at liquid side
and gas side, and connect the vacuum pump as shown in the following figure.
Perform vacuuming for liquid side and gas side.
• Perform vacuuming from both liquid side and gas side.
• Use a vacuum pump with counter-flow preventive function so that oil in the pump does not back up in the pipe
of the air conditioner when the pump has been stopped. (If oil in the vacuum pump enters in to the air conditioner
an error may occur in the refrigeration cycle.)
Connected to indoor unit
Main pipe
Fully closed
Fully closed
• Use a vacuum pump that has a high vacuum (below -100.7kPa (-755mmHg)) and a large exhaust gas amount
(over 40 L / minute).
• Perform vacuuming for 2 or 3 hours though time differs due to pipe length.
In this time, check all valves at liquid and gas sides are fully closed.
• If vacuuming valve amount is not decreased to below -100.7kPa even after vacuuming for 2 hours or more,
continue vacuuming for 1 hour or more.
If -100.7kPa or less cannot be obtained by 3 hours or more vacuuming, detect and repair the leak.
• When the vacuuming valve has reached -100.7kPa or less after vacuuming for 2 hours or more, close valves VL
and VH on the gauge manifold fully. Stop the vacuum pump, leave it as it is for 1 hour and then check the vacuum
does not change. If it does change then there may be a leak within the system.
• After the above procedure for vacuuming has finished, exchange the vacuum pump with a refrigerant cylinder
and advance to the additional charging of refrigerant.
– 32 –
High pressure
Low pressure
gauge gauge
Packed valve fully closed
(gas side)
V V
Gauge
L H
Outdoor unit
manifold
Service port
Service port
Packed valve fully closed
Vacuum pump
(liquid side)
EN
64-EN