Carrier 38VT 188CTST Series - Page 20

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EN
 Airtightness test
After the refrigerant piping has been ¿nished, execute an airtight test.
For an airtight test, connect a nitrogen gas canister as shown in the ¿gure on this page and apply pressure.
• Be sure to apply pressure from the service ports of the packed valves (or ball valves) at the liquid side and gas
side.
• An airtight test can only be performed at the service ports at the liquid side and gas side on header unit.
• Close the valves fully at the gas side and liquid side. As there is a possibility that the nitrogen gas will enter into
the cycle of outdoor units, re-tighten the valve rods at the liquid side before applying pressure.
• For each refrigerant line, apply pressure gradually in steps at the liquid side and gas side.
Be sure to apply pressure at the gas side and liquid side.
WARNING
Never use oxygen, Àammable gases, or noxious gases in an airtight test.
V
L
V
H
Valve details
To gauge
manifold
Liquid-side
valve
Liquid-side
service port
Piping at site
To
outdoor
unit
To outdoor unit
Gas-side valve
Gas-side
service port
Piping at site
Connected to other follower units
Main piping
Connected to indoor unit
Low pressure
gauge
High pressure
gauge
Gauge
manifold
Reducing
valve
Copper
pipe
Nitrogen
gas
Service port
Brazed
Brazed
Gas side valve fully closed
Header outdoor unit
Copper pipe
Service port
Liquid valve fully closed
Able to detect a serious leakage
1. Apply pressure 0.3 MPa (3.0 kg/cm
2
G) for 5 minutes or more.
2. Apply pressure 1.5 MPa (15 kg/cm
2
G) for 5 minutes or more.
Available to detect slow leakage
3. Apply pressure 4.15 MPa (42.3 kg/cm
2
G) for approx. 24 hours.
• If there is no pressure decrease after 24 hours, the test is passed.
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/cm
2
G) 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, Àare retightening
or other methods. After sealing, execute an airtight test again.
IM_1141001201-1_Book.indd 68 7/1/2564 BE 12:02