Mitsubishi Heavy Industries 140KXZEN1 Service Manual Download

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Fix both liquid and gas service valves at the valve main bodies as illustrated on the right,
and then fasten them, applying appropriate fastening torque.

Tightening angle

(

)

Tightening torque

(N·m)

6.35 (1/4")

9.52 (3/8")

12.7 (1/2")

15.88(5/8")

150
200
250
300

Use a torque wrench. If a torque wrench is not available,
fasten the flare nut manually first and then tighten it
further, using the left table as a guide.

Recommended length

of a tool handle (mm)

Service valve size

(mm)

Do not hold the valve cap area with a spanner.

●

Do not apply any oil on a flare joint.

●

Blazing must be performed under a nitrogen gas flow

. Without nitrogen gas, a large quantity of foreign matters (oxidized film) are created, causing a critical failure

from capillary tube or expansion valve clogging.

●

Brazing of the service valve and the pipes should be performed while cooling the valve body with a wet towel.

●

Perform flushing. To flush the piping, charge nitrogen gas at about 0.02MPa with a pipe end closed with a hand. When pressure inside builds up to a sufficient
level, remove the hand to flush. (in flushing a pipe, close the other end of the pipe with a plug).

Plug the end of the pipe with tape, or other
material, and fill the pipe with nitrogen gas.

Only use nitrogen gas (N

２

)

Taping

＜

２

＞

Nitrogen

Brazing

Flatten

Adhesive tape

Station valve

Primary side

Secondary side

0.02MPa

Hand

Relief valve

Nitrogen

gas

Operation procedure

①

During the pipe installation at site, keep the service valves shut all the time

②

Blazing must be performed under a nitrogen gas flow

. Without nitrogen gas, a large

quantity of foreign matters (oxidized film) are created, causing a critical failure from
capillary tube or expansion valve clogging.

③

Give

sufficient protections

(compressed and brazed or with an adhesive

tape)

so that water or foreign matters may not enter the piping

④

Perform flushing. To flush the piping, charge nitrogen gas at about 0.02MPa with a pipe

end closed with a hand. When pressure inside builds up to a sufficient level, remove the
hand to flush. (in flushing a pipe, close the other end of the pipe with a plug).

Nitrogen

gas

①

Although an outdoor unit itself has been tested for air tightness at the factory, please check the connected pipes and indoor units for air tightness from the check

joint of the service valve on the outdoor unit side. While conducting a test,

keep the service valve shut all the time

②

Since refrigerant piping is pressurized to the design pressure of a unit with nitrogen gas for testing air tightness, please connect instruments according the drawing below.

Under no circumstances should chlorine-based refrigerant, oxygen or any other combustible gas be used to pressurize a system.

Keep the service valve shut all the time

. Do not open it under any circumstances.

Be sure to pressurize all of the liquid, gas pipes

③

In pressurizing the piping, do not apply the specified level of pressure all at once, but gradually raise pressure.
a)

Raise the pressure to 0.5 MPa, and then stop. Leave it for five minutes or more

to see if the pressure drops.

Then raise the pressure to 1.5 MPa, and stop. Leave it for five more minutes

to see if the pressure drops.

c) Then raise the pressure to the specified level (4.15 MPa), and record the ambient temperature and the pressure.
d)

If no pressure drop is observed with an installation pressurized to

the specified level

and left for about one day

it is acceptable

. When the ambient temperature

changes 1

℃

, the pressure also changes approximately 0.01 MPa. The pressure, if changed, should be compensated for.

e) If a pressure drop is observed in checking e) and a) – d), a leak exists somewhere. Find a leak by applying bubble test liquid to welded parts and flare joints and

repair it. After repair, conduct an air-tightness test again.

④

Always pull air from the pipes after the airtightness test.

To indoor unit

Gauge manifold

Lo knob

Hi knob

Service point

(check joint)

Service valve

Liquid pipe

Gas pipe