Hitachi YUTAKI S Serie Manual De Instalación Y Funcionamiento página 23

PIPING AND
REFRIGERANT CHARGE
10. PIPING AND REFRIGERANT CHARGE

CAUTION:
- Use refrigerant R410A in the refrigerant cycle. Do
not charge oxygen, acetylene or other flammable
and poisonous gases into the refrigerant cycle when
performing a leakage test or an air-tight test.
- These types of gases are extremely dangerous and can
cause an explosion. It is recommended that compressed
air, nitrogen or refrigerant be used for these types of tests.
- Check to ensure that no pressure exists inside the stop
valve before removing the flange.
■
Evacuation and Refrigerant Charge
Evacuation and refrigerant charging procedure should be
performed 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. Suspend the refrigerant piping at certain
points and prevent the refrigerant piping from touching the
weak part of the building such as wall, ceiling, etc., (If touched,
abnormal sound may occur due to the vibration of the piping.
Pay special attention in case of short piping length)
Apply refrigerant oil thinly to the seat surface of flare nuts and
pipe before tightening.
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 HRNME
outdoor units inside of the field-supplied piping.
Operate the vacuum pump for 1 to 2 hours until the pressure
decreases lower than a pressure of 756 mmHg in vacuum.
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 refrigerant
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.
Outdoor Unit
Gas Stop valve
Liquid
Gas Line
Line
Indoor Unit
Example of Evacuation and Refrigerant Charge for HRNME

NOTE:
Charge the refrigerant correctly after calculation.
-
Overcharge and insufficient charge of the refrigerant may
cause the compressor failure. Insulate the liquid pipe
for prevention of the capacity decrease according to the
ambient air conditions and the dewing on the pipe surface
by the low pressure.
- Check to ensure that there is no gas leakage. When large
amount of the refrigerant leaks, the troubles as follows
may occur:
- Oxygen deficiency
- Generation of Harmful gas Due to Chemical Reaction
with fire.
- Use thick gloves to protect your hands from liquid
refrigerant injuries when handling refrigerant.

CAUTION:
Check for refrigerant leakage in detail. If a large
refrigerant leakage occurs, it will cause difficulty with
breathing or harmful gases would occur if a fire was being
used in the room. An excess or a shortage of refrigerant is
the main cause of trouble to the units. Charge the correct
refrigerant quantity.
PMML0215A rev.1 - 02/2012
Nitrogen tank
(For Air Tight
Test & Nitrogen
Blow during
Brazing)
Charging
Cylinder
Liquid Stop Vacuum
valve cylinder
25