Mitsubishi Electric American Standard NAXSKS18A112A Série Manuel D'installation page 5

4. Refrigerant piping work
D
C
Fig. 4-4
(inch)
A
45˚± 2˚
Flare cutting dimensions
A
Flare nut tightening torque
B
Fig. 4-5
4.4. Purging procedures and leak test
1) Remove service port cap of stop valve on the side of the outdoor unit gas pipe.
2) Connect gauge manifold valve and vacuum pump to service port of stop valve on
the gas pipe side of the outdoor unit.
Stop valve cap
*4 to 5 turns
(Torque 19.6 to
*Close 29.4 N•m, 200 to
Stop valve for
300 kgf•cm)
*Open
LIQUID
Hexagonal
wrench
Service port cap
(Torque 13.7 to 17.7
N•m, 140 to 180
kgf•cm)
Precautions when using the control valve
Service port
A
Control valve
Open
Close Charge hose
Body
Liquid pipe
A
B
Gas pipe
B
Insulation
C
Taping
D
A
B
C
D
–0.101 MPa
Compound pressure gauge
(–30 in.Hg
(for R410A)
[–760 mmHg])
Pressure gauge
(for R410A)
Gauge manifold valve
(for R410A)
Handle
Handle High
Low
Charge hose
Stop valve for
(for R410A)
GAS
Adapter for
preventing the
Vacuum pump (or the vacuum
back flow
pump with the function to
prevent the back flow)
When attaching the control valve to the
service port, valve core may deform or
loosen if excess pressure is applied.
This may cause gas leak.
When attaching the control valve to the
service port, make sure that the valve
core is in closed position, and then
tighten part A. Do not tighten part A
or turn the body when valve core is in
open position.
4.3. Connecting pipes (Fig. 4-4, Fig. 4-5)
• Fasten flare nut with a torque wrench as specified in the table (refer to 4.2.).
• When fastened too tight, flare nut may eventually break and cause refrigerant leak-
age.
[Fig. 4-5]
• Apply thin layer of refrigerant oil to pipe and joint seating surface before tightening
flare nut.
A
• Use 2 wrenches to tighten piping connections.
• Use leak detector or soapy water to check for gas leaks after connections are
completed.
• Apply refrigerant oil over the entire flare seat surface.
• Use the flare nuts for the following pipe size.
Gas side Pipe size inch (mm)
Liquid side Pipe size inch (mm)
*1: The flare nut is attached to its pipe.
*2: The flare nut is in the outdoor unit accessory.
Do not use the flare nuts other than the attachment. If it is used, a gas leakage or
even a pipe extraction may occur.
• Refrigerant pipe bending radius must be 4 in. (100 mm) or more.
• Make sure the pipes do not contact the compressor. Abnormal noise or vibration
may result.
Pipes must be connected starting from the indoor unit.
1
Flare nuts must be tightened with a torque wrench.
Flare the liquid pipes and gas pipes and apply a thin layer of refrigerant oil
2
(Applied on site).
Warning:
Be careful of flying flare nut. (Internally pressurized)
Remove the flare nuts as follows:
1. Loosen the nut until you hear a hissing noise.
2. Do not remove the nut until the gas has been completely released (i.e., hiss-
ing noise stops)
3. Check that the gas has been completely released, and then remove the nut.
(Fig. 4-5)
A
Pipe diameter
inch (mm)
1/4" (6.35) 11/32 - 23/64
3/8" (9.52) 1/2 - 33/64
1/2" (12.7) 41/64 - 21/32
5/8" (15.88) 49/64 - 25/32
3) Run the vacuum pump 15 minutes or more.
4) Check the vacuum with the gauge manifold valve, then close it and shut off the
vacuum pump.
5) Leave as it is for one or two minutes. Make sure pointer gauge manifold valve
remains in the same position. Confirm that pressure gauge shows -0.101 MPa
[Gauge] (-30 in.Hg [-760 mmHg]).
6) Quickly remove gauge manifold valve from service port of stop valve.
7) After refrigerant pipes are connected and evacuated, fully open all stop valves on
both sides of gas pipe and liquid pipe. Operating the unit without fully opening the
valves lowers the performance and causes problems.
8) Refer to 4.1. Refrigerant pipe, and charge the prescribed amount of refrigerant if
needed. Be sure to charge slowly with liquid refrigerant. Otherwise, composition
of the refrigerant in the system may be changed and affect performance of the air
conditioner.
9) Tighten cap of service port.
10) Conduct a leak test.
B
C
D
NAXSKS24A112A
NAXSKS18A112A NAXSKS30A112A
NAXSKS36A112A
1/2 (12.7) 5/8 (15.88)
1/4 (6.35) 3/8 (9.52)
Flare dimensions
øA dimensions
inch (mm)
(8.7 - 9.1)
(12.8 - 13.2)
(16.2 - 16.6)
(19.3 - 19.7)
5