Refrigerant Charge - Hitachi Ras-2Hvnp Installations- Und Betriebshandbuch

14
1 Refrigerant piping & refrigerant charge

14.4 REFRIGERANT CHARGE

C A U T I O N
Do not charge OXYGEN, ACETYLENE, or other flammable
•
and poisonous gases into the refrigerant because an explo-
sion can occur. It is recommended that oxygen free nitrogen
be charged for these types of tests cycle when performing
a leakage test or an airtight test. These types of gases are
extremely dangerous,
Insulate the unions and flare-nuts at the piping connection
•
part completely.
• Insulate the liquid piping completely to avoid a decrease of
performance; if not, it will cause sweating on the surface of
the pipe.
Charge refrigerant correctly. Overcharging or insufficient char-
•
ging could cause a compressor failure.
• Check for refrigerant leakage in detail. If a large refrigerant
leakage occurred, it would cause difficulty with breathing or
harmful gases would occur if a fire were being used in the
room.
If the flare nut mut is tigthened too hard, the flare nut may
•
crack after a long time and cause refrigerant leakage.
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Evacuation and refrigerant charge
Evacuation and refrigerant charging procedure should be perfor-
med according to the following instructions.
The stop valve has been closed before shipment. However, make
sure that the stop valves are closed completely.
Connect the indoor unit and the outdoor unit with field-
-
supplied refrigerant piping.
Connect the gauge manifold using charging hoses with a
-
vacuum pump or a nitrogen cylinder to the check joints of
the liquid line and the gas line stop valve.
Check for any gas leakage at the flare nut connection, by
-
using nitrogen gas to increase the pressure at 4.15MPa
for outdoor units inside of the field-supplied piping.
Operate the vacuum pump for 1 to 2 hours until the pres-
-
sure decreases lower than a pressure of 756 mmHg in
vacuum.
14.5 CAUTION OF THE PRESSURE BY CHECK JOINT
When the pressure is measured, use the check joint of gas stop
valve, and use the check joint of liquid piping in the figure below.
At that time, connect the pressure gauge according to the fo-
llowing table because of high pressure side and low pressure side
changes by operation mode.
Check Joint for Gas Stop Valve
Check Joint for Liquid Stop Valve
27
PMML0248A
Cooling Heating
Operation Operation
Low Pressure High Pressure
Exclussive for Vacuum Pump
and Refrigerant Charge
For charging refrigerant, connect the gauge manifold
-
using charging hoses with a refrigerant charging cylinder
to the check joint of the liquid line stop valve.
Charge the proper quantity of refrigerant according to
-
the piping length (Calculate the quantity of the refrigerant
charge).
Fully open the gas line stop valve, and slightly open the
-
liquid line stop valve.
Charge refrigerant by opening the gauge manifold valve.
-
Charge the required refrigerant within the difference range
-
of ±0.5kg by operating the system in cooling.
Fully open the liquid line stop valve after completing refri-
-
gerant charge.
Continue cooling operation for more than 10 minutes to
-
circulate the refrigerant.
Remove the "close" plate from the stop valve and hook the
-
attached "Open" plate at the stop valve.
Gas line
Liquid stop valve
Outdoor unit
Gas stop valve
Manifold
gauge
Vacuum cylinder
Example of Evacuation and Refrigerant Charge for HVN(P/C)
N O T E
Be careful that refrigerant and oil do not splash to the electrical
parts at removing the charge hoses.
Liquid line
Nitrogen tank
(For air tight test & nitrogen blow
during brazing)
Stop valve (liquid)
Stop valve (gas)