Hitachi RAS-10HNCE, Installation And Operation Manual

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PMML0251A rev.2 - 02/2013 26
Refrigerant piping & refrigerant charge
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Evacuation and refrigerant charge
- 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 4.15 MPa
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.
- For charging refrigerant, connect the gauge manifold us-
ing 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 refrig-
erant charge.
-
Continue cooling operation for more than 10 minutes to
circulate the refrigerant.
Thermal insulation
Gas line
Cover the flare nut and union
of the piping connection with
thermal insulation
Liquid line
Liquid stop valve
Gas stop valve
Nitrogen tank
(For air Tight test
& Nitrogen blow
during brazing)
Vacuum cylinder
Manifold
gauge
Outdoor unit
Insulate the liquid pipe for
prevention of the capacity
decrease according to the
ambient air conditions and
the dewing on the pipe sur-
face by the low pressure
Example of Evacuation and Refrigerant Charge.
13.4 REFRIGERANT PIPING LENGTH
The refrigerant piping between the indoor unit and the outdoor unit should be designed using the following table.
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Piping length specification for header branch
(Example for header branch)
1 indoor unit system (O.U. from 3 to 10 HP) 2 indoor units system (O.U. from 3 to 10 HP) 3 indoor units system (O.U. from 4 to 10 HP)
4 indoor units system (O.U. from 4 to 10 HP)
(pictures are as example)
_PMML0251A_r2.indb 26 06/02/2013 9:05:04