Airtight Test, Evacuation, And Refrigerant Charging - Mitsubishi Electric PUH-P10MYA Installation Manual

H Flare nut
[Tightening torque: 120 N·m (1200 kg·cm)
Loosen and tighten this nut using a double-ended wrench.
Coat the flare contact surface with refrigerator oil (Ester oil, ether oil or alkylbenzene
[small amount]).]
I ø12.7 PUH-P8, 10
J ø25.4 PUH-P8
ø28.58 PUH-P10
K Field piping
[Braze to the connecting pipe. (When brazing, use unoxidized brazing.)]
L Close-packed packing
M Hollow packing
Appropriate tightening torque by torque wrench:
Copper pipe external dia. (mm)
ø6.35
ø9.52
ø12.7
ø15.88
Tightening angle standard:
Pipe diameter (mm) Tightening angle (°)
ø6.35, ø9.52 60 to 90
ø12.7, ø15.88 30 to 60
[Fig. 8.2.3] (P.3)
Note:
If a torque wrench is not available, use the following method as a standard:
When you tighten the flare nut with a wrench, you will reach a point where
the tightening torque will abrupt increase. Turn the flare nut beyond this point
by the angle shown in the table above.
1. Nitrogen gas pressurization
(1) After pressurizing to the design pressure (3.3 MPa) using nitrogen gas, let stand for about one
day. If the pressure does not drop, airtightness is good.
However, if the pressure drops, since the leaking point is unknown, the following bubble test
may also be performed.
(2) After the pressurization described above, spray the flare connection parts, brazed parts, flanges,
and other parts that may leak with a bubbling agent (Kyuboflex, etc.) and visually check for
bubbles.
(3) After the airtight test, wipe off the bubbling agent.
2. Pressurization using refrigerant gas and nitrogen gas
(1) Pressurizing to a gas pressure of approximately 0.2 MPa, pressurize to the design pressure
(2.94 MPa) using nitrogen gas.
However, do not pressurize at one time. Stop during pressurization and check that the pres-
sure does not drop.
(2) Check for gas leaks by checking the flare connection parts, brazed parts, flanges, and other
parts which may leak using an R407C compatible electric leak detector.
(3) This test may be used together the with bubble type gas leak test.
2 Evacuation
Evacuate with the ball valve of the outdoor unit closed and evacuate both the
connection piping and the indoor unit from the service port provided on the ball
valve of the outdoor unit using a vacuum pump. (Always evacuate from the
service port of both the liquid pipe and the gas pipe.) After the vacuum reaches
5 Torr, continue evacuation for at least one hour or more.
* Never perform air purging using refrigerant.
[Fig. 8.3.2] (P.3)
A System analyzer B Lo Knob
D Ball valve E Liquid pipe
G Service port H Three-way joint
J Valve K Cylinder
M Vacuum pump
Note:
• Always add an appropriate amount of refrigerant. Also always seal the
system with liquid refrigerant. Too much or too little refrigerant will cause
trouble.
• Use a gauge manifold, charging hose, and other parts for the refrigerant
indicated on the unit.
10
Tightening torque (N·m) / (kg·cm)
14 to 18 / 140 to 180
35 to 42 / 350 to 420
50 to 57.5 / 500 to 575
75 to 80 / 750 to 800
Airtight test procedure
C Hi Knob
F Gas pipe
I Valve
L Scale
Caution:
• Always remove the connecting pipe from the ball valve and braze it out-
side the unit.
- Brazing the connecting pipe while it is installed will heat the ball valve and
cause trouble or gas leakage. The piping, etc. inside the unit may also be
burned.
• Use ester oil, ether oil or alkylbenzene (small amount) as the refrigerator
oil to coat flares and flange connections. (For R407C models)
- The refrigerator oil will degrade if it is mixed with a large amount of mineral
oil.
8.3. Airtight test, evacuation, and refriger-
ant charging
1 Airtight test
Perform with the stop valve of the outdoor unit closed, and pressurize the
connection piping and the indoor unit from the service port provided on the
stop valve of the outdoor unit. (Always pressurize from both the liquid pipe and
the gas pipe service ports.)
[Fig. 8.3.1] (P.3)
A Nitrogen gas B To indoor unit
D Lo Knob E Hi Knob
G Liquid pipe H Gas pipe
J Service port
<For R407C models>
The method of conducting the airtight test is basically the same as for R22 models.
However, since the restrictions have a large affect on deterioration of the refrigera-
tor oil, always observe them. Also, with nonazeotropic refrigerant (R407C, etc.),
gas leakage causes the composition to change and affects performance. There-
fore, perform the airtightness test cautiously.
• If a flammable gas or air (oxygen) is used as the pressurization
gas, it may catch fire or explode.
• Do not use a refrigerant other than that indicated on the unit.
• Sealing with gas from a cylinder will cause the composition of
the refrigerant in the cylinder to change. (For R407C models)
• Use a pressure gauge, charge box, and other parts especially for
R407C. (For R407C models)
• An electric leak detector for R22 cannot detect leaks of R407C.
• Do not use a haloid torch. (Leaks cannot be detected.)
• Use a graviometer. (One that can measure down to 0.1 kg.)
• Use a vacuum pump with a reverse flow check valve. (For R407C mod-
els)
(Recommended vacuum gauge: ROBINAIR 14830A Thermistor Vacuum
Gauge)
Also use a vacuum gauge that reaches 0.5 Torr or greater after operating
for five minutes.
3 Refrigerant Charging (For R407C models)
Since the refrigerant used with the unit is nonazerotropic, it must be charged in
the liquid state. Consequently, when charging the unit with refrigerant from a
cylinder, if the cylinder does not have a syphon pipe, charge the liquid refriger-
ant by turning the cylinder upside-down as shown below. If the cylinder has a
syphon pipe like that shown in the figure at the right, the liquid refrigerant can
be charged with the cylinder standing upright. Therefore, give careful attention
to the cylinder specifications. If the unit should be charged with gas refrigerant,
replace all the refrigerant with new refrigerant. Do not use the refrigerant re-
maining in the cylinder.
[Fig. 8.3.3] (P.3)
C System analyzer
F Stop valve
I Outdoor unit
Restriction