Hitachi RAS-3HVRNME-AF, Installation And Operation Manual, Page: 28 / 40

PMML0205A rev.4 - 11/2012
28
Example of YUTAKI S80
refrigerant piping length
Maximum piping length between
outdoor unit and indoor unit (Lmax)
Actual piping length 30 m
Equivalent piping length 40 m
Minimum piping length between
outdoor unit and indoor unit (Lmin)
Actual piping length 3 m
Maximum height difference bet-
ween indoor and outdoor unit (H)
Outdoor unit higher
than indoor unit
30 m
Indoor unit higher than
outdoor unit
20 m
10.4.2. REFRIGERANT PIPING SIZE
Piping connection size of Outdoor Unit & Indoor Unit
Outdoor Unit
Pipe Size
Gas Pipe Liquid Pipe
(3
~
6) HP
Ø
15.88 (5/8”)
Ø
9.53 (3/8”)
Indoor Unit
Pipe Size
Gas Pipe Liquid Pipe
(3 ~ 6) HP Ø 15.88 (5/8”) Ø 9.53 (3/8”)
10.4.3. BRAZING WORK

ATTENTION:
Use nitrogen gas for blowing during pipe brazing. If oxygen,
acetylene or fluorocarbon gas is used, it will cause an explosion
or poisonous gas.
A lot of oxidation film will occur inside of tubes if no nitrogen
gas blowing is performed during brazing work. This film will be
flecked off after operation and will circulate in the cycle, resulting
in clogged expansion valves, etc. This will cause bad influence to
the compressor.
Use a reducer valve when nitrogen gas blowing is performed
during brazing. The gas pressure should be maintained within
0.03 to 0.05 MPa. If a excessively high pressure is applied to a
pipe, it will cause an explosion.
10.5. CAUTION OF THE PRESSURE BY CHECK JOINT
When the pressure is measured, use the check joint of gas stop
valve (A) and use the check joint of liquid stop valve (C) in the
figure below.
At that time, connect the pressure gauge according to the
following table because high pressure side and low pressure
side changes by operation mode.
Cooling
Operation (*)
Heating
Operation
Check Joint for Gas Stop Valve “A” Low Pressure High Pressure
Check Joint for Piping “B”
Exclusive for Vacuum
and Refrigerant Charge
Check Joint for Liquid Stop Valve “C” High Pressure Low Pressure
3HVRNME-AF
(4-6)H(V)RNME-AF

NOTE:
Be careful that refrigerant and oil do not splash to the electrical
parts at removing the charge hoses.
(*) YUTAKI S: cooling operation only applies some models.
YUTAKI S80: cooling operation is only used as pump down
operation.
REFRIGERANT PIPING &
REFRIGERANT CHARGE