Table of Contents
Advertisement
Leak Test and Vacuum drying
Leak test
Leak test should be made by pressurizing nitrogen gas to
3.8MPa(551.1psi). If the pressure does not drop for 24 hours, the sys-
tem passes the test. If the pressure drops, check where the nitrogen
leaks. For the test method, refer to the following figure. (Make a test
with the service valves closed. Be also sure to pressurize liquid pipe,
gas pipe and high/low pressure common pipe)
The test result can be judged good if the pressure has not be reduced
after leaving for about one day after completion of nitrogen gas pres-
surization.
During this test, set DIP switch as Vacuum Mode.
Nitrogen gas cylinder
NOTE
!
If the ambient temperature differs between the time when pressure is
applied and when the pressure drop is checked, apply the following
correction factor
There is a pressure change of approximately 0.01 Mpa (1.5 psi) for
each 1 °C of temperature difference.
Correction= (Temp. at the time of pressurization – Temp. at the time of
check) X 0.1
For example: Temperature at the time of pressurization
3.8 MPa (551 psi) is 27 °C (81 °F).
24 hour later: 3.73MPa(541psi), 20 °C (68 °F)
In this case the pressure drop of 0.07 MPa(10 psi) is be-
cause of temperature drop
And hence there is no leakage in pipe occurred.
CAUTION
!
To prevent the nitrogen from entering the refrigeration system in
the liquid state, the top of the cylinder must be at higher position
than the bottom when you pressurize the system.
Usually the cylinder is used in a vertical standing position.
Vacuum
Vacuum drying should be made from the service port provided on the outdoor
unit's service valve to the vacuum pump commonly used for liquid pipe, gas
pipe and high/low pressure common pipe. (Make Vacuum from liquid pipe, gas
pipe and high/low pressure common pipe with the service valve closed.)
* Never perform air purging using refrigerant.
• Vacuum drying: Use a vacuum pump that can evacuate to -100.7 kPa (-14.6
psi, 5 Torr, -755 mmHg).
1. Evacuate the system from the liquid and gas pipes with a vacuum pump for
over 2 hrs and bring the system to -100.7 kPa (-14.6 psi).
After maintaining system under that condition for over 1 hr, confirm the vac-
uum gauge rises. The system may contain moisture or leak.
2. Following should be executed if there is a possibility of moisture remaining
inside the pipe.
(Rainwater may enter the pipe during work in the rainy season or over a long
period of time)
After evacuating the system for 2 hrs, give pressure to the system to 0.05
MPa (7.3 psi)(vacuum break) with nitrogen gas and then evacuate it again
with the vacuum pump for 1hr to -100.7 kPa (-14.6 psi)(vacuum drying). If
the system cannot be evacuated to -100.7 kPa (-14.6 psi) within 2 hrs, re-
peat the steps of vacuum break and its drying.
Finally, check if the vacuum gauge does not rise or not, after maintaining the
system in vacuum for 1 hr.
Vacuum pump
WARNING
!
• If the primary charging is not performed after vacuum, wet air
may go into the outdoor unit. If air is mixed with the refrigerant,
the refrigerant cycle may malfunction and the unit may be dam-
aged.
• Charging of refrigerant while the compressor is working is pro-
hibited. Otherwise, liquid may go into the compressor. It may
cause faults of the compressor.
• Use a gravimeter accurate to 0.1 kg (0.22 lbs).
• If other refrigerants are mixed in the original refrigerant, a refrig-
erant cycle may cause malfunction or damage.
• Add accurate refrigerant quantity via calculation.
Too much or too little refrigerant may cause problems
• Repeated on and off of the indoor units without charging refrig-
erant may cause faults of EEV.
• Since R410A is a mixed refrigerant, the required additional re-
frigerant must be charged in its liquid state. If the refrigerant is
charged in its gaseous state, its composition changes and the
system will not work properly.
13
Advertisement
Table of Contents
