Air Tightness Test; Evacuation; Heating And Condensation Prevention - Mitsubishi Electric DXK09ZJ-S Technical Manual

its form.
●
Flare connection is used between the unit and refrigerant pipe. Flare a pipe after engaging a
flare nut onto it. Flare dimensions for R410A are different from those for conventional R407C.
Although we recommend the use of flaring tools designed specifically for R410A, conventional
flaring tools can also be used by adjusting the measurement of protrusion B with a protrusion
control gauge.
● The pipe should be anchored every 1.5m or less to isolate the vibration.
●
Tighten a flare joint securely.
CAUTION Do not apply force beyond proper fastening torque in tightening the flare nut.
Fix both liquid and gas operation valves at the valve main bodies as illustrated on the right, and then fasten
them, applying appropriate fastening torque.
Operation valve size (mm) Tightening torque (N·m)
φ6.35 (1/4")
φ9.52 (3/8")

5) Air tightness test

① Although outdoor and indoor units themselves have been tested for air tightness at the factory, check the connecting pipes after the installation work for air tightness
from the operation valve's check joint equipped on the outdoor unit side. While conducting a test, keep the operation valve shut all the time.
a) Raise the pressure to 0.5 MPa, and then stop. Leave it for five minutes to see if the pressure drops.
b) 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 fall
1℃, the pressure also fall 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.
② In conducting an air-tightness test, use nitrogen gas and pressurize the system with nitrogen gas from the gas side. Do not use a medium other than nitrogen gas
under any circumstances.

6) Evacuation

＜Work flow＞
When the system has remaining moisture
inside or a leaky point, the vacuum gauge
indicator will rise.
Check the system for a leaky point and
then draw air to create a vacuum again.
Pay attention to the following points in addition to the above for the R410A and
compatible machines.
○ To prevent a different oil from entering, assign dedicated tools, etc. to each refrigerant
type. Under no circumstances must a gauge manifold and a charge hose in particular
be shared with other refrigerant types (R22, R407C, etc.).
○ Use a counterflow prevention adapter to prevent vacuum pump oil from entering the
refrigerant system.

7) Heating and condensation prevention

(1) Dress refrigerant pipes (both gas and liquid pipes) for heat insulation and prevention of dew condensation.
Improper heat insulation/anti-dew dressing can result in a water leak or dripping causing damage to household effects, etc.
●
(2) Use a heat insulating material that can withstand 120℃ or a higher temperature. Poor heat insulating capacity can cause heat insulation problems or cable
deterioration.
All gas pipes must be securely heat insulated in order to prevent damage from dripping water that comes from the condensation formed on them during a cooling operation
●
or personal injury from burns because their surface can reach quite a high temperature due to discharged gas flowing inside during a heating operation.
Wrap indoor units' flare joints with heat insulating parts (pipe cover) for heat insulation (both gas and liquid pipes).
●
Give heat insulation to both gas and liquid side pipes. Bundle a heat insulating material and a pipe tightly together so that no gaps may be left between them and wrap them
●
together with a connecting cable by a dressing tape.
Both gas and liquid pipes need to be dressed with 20 mm or thicker heat insulation materials above the ceiling where relative humidity exceeds 70%.
●
3. DRAIN PIPING WORK
● Execute drain piping by using a drain elbow and drain
grommets supplied separately as optional parts, where
water drained from the outdoor unit is a problem.
● Water may drip where there is a larger amount of drain
water. Seal around the drain elbow and drain grommets
with putty or adequate caulking material.
Tightening angle (° ) Recommended length of a tool handle (mm)
45∼60 150
14∼18
34∼42 30∼45 200
Airtighteness test completed
Vacuuming begins
Run the vacuum pump for at least one hour after the vacuum
gauge shows -101kPa or lower. (-755mmHg or lower)
Vacuuming completed
Confirm that the vacuum gauge indicator does not rise even if
the system is left for one hour or more.
Vacuum gauge check
Fill refrigerant
CAUTION
Do not put a grommet
Copper pipe protrusion for flaring : B
Copper
pipe outer
diameter
φ6.35
φ9.52
Side cover
The screw of the side cover
is tightened securely.
Do not hold the valve cap area with a spanner.
Outdoor unit
Operation Valve
Cap
Operation Valve
(two-way valve)
-0.1MPa
(-76cmHg)
Handle Lo
Operation Valve
(three-way valve)
Operation Valve
Cap
Check joint
Securely tighten the operation valve cap and the check joint blind nut after adjustment.
Operation valve size Operation valve cap
tightening torque (N·m)
(mm)
φ6.35 (1/4")
20∼30
φ9.52 (3/8")
Wires for connecting indoor
and outdoor units
Liquid piping
(mm)
In the case of a rigid (clutch) type
With an R410A tool With a conventional tool
0∼0.5 1.0∼1.5
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.
Gas side
operation valve
Indoor unit
Check joint
Compound pressure gauge
Pressure gauge
Gauge Manifold
(Designed specifically for R410A)
Handle Hi.
Charge hose
(Designed specifically for R410A)
Vacuum pump adapter
(Anti-reverse flow type)
(Designed specifically for R410A)
Vacuum pump
Charge hose
(Designed specifically for R410A)
Check joint blind nut
tightening torque (N·m)
10∼12
Band (accessory)
Pipe cover (accessory)
Exterior tape
Gas piping
Insulation
● When condensed water needs to be
led to a drain, etc., install the unit on
a flat base (supplied separately as an
Use polychloroprene sheathed flexible cord (cod
Ground the unit. Do not connect the grounding wire to
●
If impropery grounded, an electric shock or malf
A grounding wire must be connected before conn
●
The installation of an impulse withstanding type
●
acccident such as an electric shock or a fire.
Do not turn on the power until the electrical work
●
Do not use a condensive capacitor for power fact
●
an abnormal overheat accident)
For power supply cables, use conduits.
●
Do not lay electronic control cables (remote contr
●
in the malfunctioning or a failure of the unit due
Fasten cables so that may not touch the piping, e
●
When cables are connected, make sure that all el
●
terminal connection and then attach the cover s
penetrates into the box.)
Always use a three-core cable for an indoor-outd
●
Power su
Cable cla
○ It holds
connec
○ This cla
diamet
Please
Cable na
○ It has s
Groundin
○ Please
ground
Indoor - Outdoor Power cab
connecting wire
power cable, indoor - outdoor conn
INSTALLATION TEST
Check the following points again after completion
Explain to the customer how to use the unit and
After installation
Power cables and connecting wires are se
The power supply voltage is correct as the
The drain hose is fixed securely.
Operational valve is fully open.
No gas leaks from the joints of the operat