Precautions Concerning Piping Connection And Valve Operation - Mitsubishi Electric CITY MULTI PURY-P-THMU-A (-BS) Manuel D'installation

<Example>
Indoor 1: 30 A: ø28.58 mm [1-1/8 in]
2: 96 B: ø9.52 mm [3/8 in]
3: 12 C: ø9.52 mm [3/8 in]
4: 15 D: ø9.52 mm [3/8 in]
5: 12 E: ø9.52 mm [3/8 in]
6: 24 F: ø22.2 mm [7/8 in]
G: ø19.05 mm [3/4 in]
The total length of each liquid line is as follows:
ø28.58 mm [1-1/8 in]: A = 40 m [131 ft]
ø22.2 mm [7/8 in]: F = 3 m [10 ft]
ø19.05 mm [3/4 in]: G = 1 m [4 ft]
ø9.52 mm [3/8 in]: C + D + E + a + b + f = 50 m [164 ft]
ø6.35 mm [1/4 in]: c + d + e = 20 m [64 ft]
Therefore,
<Calculation example>
Additional refrigerant charge
= 40 m [131 ft] × 0.36 kg/m [3.88 oz/ft] + 3 m [10 ft] × 0.23 kg/m [2.48 oz/ft] + 1 m [4 ft] × 0.16 kg/m [1.73 oz/ft] + 50 m [164 ft] × 0.06 kg/m [0.65 oz/ft] + 20 m [64 ft] ×
0.024 kg/m [0.26 oz/ft] + 2 kg [71 oz] + 2 kg [71 oz] + 5kg [177 oz]
= 27.8 kg [983 oz]
10.. Precautions concerning piping
connection and valve operation
• Conduct piping connection and valve operation accurately and carefully.
• Removing the pinched connecting pipe
When shipped, a pinched connecting pipe is attached to the on-site high-
pressure and low-pressure valves to prevent gas leakage.
Take the following steps 1 through 4 to remove the pinched connecting
pipe before connecting refrigerant pipes to the outdoor unit.
1 Check that the refrigerant service valve is fully closed (turned clockwise
all the way).
2 Connect a charging hose to the service port on the low-pressure/
high-pressure refrigerant service valve, and extract the gas in the
pipe section between the refrigerant service valve and the pinched
connecting pipe (Tightening torque 12 N·m).
3 After vacuuming gas from the pinched connecting pipe, sever the
pinched connecting pipe at the location shown in [Fig.10.2.1] and drain
the refrigerant.
4 After completing 2 and 3 heat the brazed section to remove the
pinched connecting pipe.
[Fig. 10..1]
<B> <A>
C
B
A
E
D
<A> Refrigerant service valve (low-pressure side/brazed type)
<B> Refrigerant service valve (high-pressure side/brazed type)
Shaft
A
Fully closed at the factory, when connecting the piping, and when
vacuuming. Open fully after these operations are completed.
<When opening>
• Turn the shaft counterclockwise with a hexagonal wrench.
• Turn around the shaft until it stops.
<When closing>
• Turn the shaft clockwise with a hexagonal wrench.
• Turn around the shaft until it stops.
Service port
B
Available for gas venting of the pinched connecting pipe, or vacuuming in the
refrigerant pipes on the site.
(Tightening torque 12 N·m)
Cap
C
Remove the cap before operating the shaft. Be sure to return it to the original
position after completing the operation.
Pinched connecting pipe severing portion
D
Pinched connecting pipe brazing portion
E
1
40 m [131 ft] a: ø9.52 mm [3/8 in] 10 m [32 ft]
10 m [32 ft] b: ø9.52 mm [3/8 in] 5 m [16 ft]
20 m [64 ft] c: ø6.35 mm [1/4 in] 5 m [16 ft]
5 m [16 ft] d: ø6.35 mm [1/4 in] 10 m [32 ft]
5 m [16 ft] e: ø6.35 mm [1/4 in] 5 m [16 ft]
3 m [10 ft] f: ø9.52 mm [3/8 in] 5 m [16 ft]
1 m [4 ft]
At the
conditions
below:
Warning:
• The sections between the refrigerant service valves and the pinched
connecting pipes are filled with gas and refrigerant oil. Extract the gas
and refrigerant oil in the above-mentioned pipe section before heating
the brazed section to remove the refrigerant service valve pinched
connecting pipe.
- If the brazed section is heated without first extracting the gas and
refrigerant oil, the pipe may burst or the pinched connecting pipe may blow
off and ignite the refrigerant oil, causing serious injury.
Caution:
• Place a wet towel on the refrigerant service valve before heating the brazed
section to keep the temperature of the valve from exceeding 10 °C [48 °F].
• Direct the flame away from the wiring and metal sheets inside the unit
to prevent heat damage.
Caution:
• Refrigerant pipe connection
This product includes connecting pipes for front piping and bottom post-
piping. (Refer to [Fig.10.2.2])
Check the high-pressure/low-pressure piping dimensions before connecting
the refrigerant pipe.
Refer to item 9.2 Refrigerant piping system for piping dimensions.
Make sure that the refrigerant pipe is not touching other refrigerants pipes,
unit panels, or base plates.
Be sure to use non-oxidative brazing when connecting pipes.
Be careful not to burn the wiring and plate when brazing.