Mitsubishi Heavy Industries SRK60ZSX-S Technical Manual page 33

4. CONNECTING PIPING WORK
1. Restrictions on unit installation
Abide by the following restrictions on unit installation.
Improper installation can cause compressor failure or performance degradation.
Dimensional restrictions
Model SRC20/25/35 Model SRC40/50/60
Connecting pipe length(L) 25m or less
Elevation difference between
15m or less
indoor and outdoor units(H)*
* Outdoor unit installation position can be higher as well as lower than the indoor unit installation position.
2. Preparation of connecting pipe
2.1. Selecting connecting pipe
Select connecting pipe according to the following table.
Model SRC20/25/35
Gas pipe ø9.52
Liquid pipe ø6.35
• Pipe wall thickness must be greater than or equal to 0.8 mm.
• Pipe material must be O-type (Phosphorus deoxidized seamless copper pipe ICS 23.040.15, ICS
77.150.30).
NOTE
If it is required to reuse the existing connecting pipe system, refer to 5. UTILIZATION OF EXISTING
PIPE.
2.2. Cutting connecting pipe
(1) Cut the connecting pipe to the required length with pipe cutter.
(2) Hold the pipe downward and remove the burrs. Make sure that no foreign material enters the pipe.
(3) Cover the connecting pipe ends with the tape.
3. Piping work
Check that both liquid and gas service valves are fully closed.
Carry out the piping work with service valves fully closed.
3.1. Flaring pipe
(1) Take out flare nuts from the service valves of outdoor unit and engage them onto connecting pipes.
(2) Flare the pipes according to table and figure shown below.
Flare dimensions for R410A are different from those for conventional refrigerant.
Although it is recommended to use the flaring tools designed specifically for R410A, conventional flaring
tools can also be used by adjusting the measurement of protrusion B with a flare adjustment gauge.
A
Copper pipe
A 0
outer diameter
–0.4
ø6.35 9.1
ø9.52 13.2
ø12.7 16.6
3.2. Connecting pipes
(1) Connect pipes on both liquid and gas sides.
(2) Tighten nuts to specified torque shown in the table below.
Operation valve size (mm) Tightening torque (N·m)
ø6.35 (1/4") 14-18
ø9.52 (3/8") 34-42
ø12.7 (1/2") 49-61
CAUTION
• Do not apply refrigerating machine oil to the flared surface. It can cause refrigerant leakage.
• Do not apply excess torque to the flared nuts. The flared nuts may crack resulting in refrigerant leakage.
5. UTILIZATION OF EXISTING PIPE
(1) Check whether an existing pipe system is reusable or not by using the following flow chart.
Are the outdoor and indoor units connected to the existing pipe system ?
YES
Is it possible to run the unit ?
YES
Does the existing unit use any of the following refrigerant oils ?
Suniso, MS,Barell Freeze, HAB, Freol, ether oil, ester oil.
YES
Do the existing pipe specifications (pipe length, pipe size and elevation difference between indoor and outdoor unit) conform to the restric-
tion of the unit.? (Go to 4.Connecting piping work and check 1.Restrictions on unit installation and 2.Preparation of connecting pipe.)
YES
NO
Is the existing pipe system free of corrosion, flaws and dents?
YES
Is the existing pipe system free of gas leaks?
NO
(Check whether refrigerant charge was required
frequently for the system before.)
YES
Are heat insulation materials of the existing pipe system
NO
free of peel-off or deterioration?
(Heat insulation is necessary for both gas and liquid pipes.)
YES
NO
Is the existing piping system free of any loose pipe support ?
YES
The existing pipe system is not reusable.
The existing pipe system is reusable.
Install the new pipe system.
H
30m or less
20m or less
Model SRC40/50/60
ø12.7
ø6.35
Liquid service valve
Gas service valve
Rigid (clutch) type
Copper pipe
outer diameter
R410A
ø6.35
ø9.52 0-0.5
ø12.7
Do not hold the valve cap area with a spanner
NO
NO
NO
NO
Repair is impossible.
Repair the damaged parts.
Repair
Air tightness is
impossible.
Check the pipe system for air tightness.
Air tightness is OK.
Repair is impossible.
Repair the damaged parts.
Repair
Repair the loose pipe support.
Repair
4. Evacuation
(1) Connect vacuum pump to gauge manifold. Connect charge hose of gauge manifold to service port
of outdoor unit.
(2) Run the vacuum pump for at least one hour after the vacuum gauge shows -0.1MPa (–76cm Hg).
(3) C onfirm that the vacuum gauge indicator does not rise even if the system is left for 15 minutes or more.
Vacuum gauge indicator will rise if the system has moisture left inside or has a leakage point.
Check the system for the leakage point. If leakage point is found, repair it and return to (1) again.
(4) Close the Handle Lo and stop the vacuum pump.
Keep this state for a few minutes to make sure that the compound pressure gauge pointer does not
L
swing back.
(5) Remove valve caps from liquid service valve and gas service valve.
(6) Turn the liquid service valve's rod 90 degree counterclockwise with a hexagonal wrench key to open
valve.
Close it after 5 seconds, and check for gas leakage.
U sing soapy water, check for gas leakage from indoor unit's flare and outdoor unit's flare and valve rods.
Wipe off all the water after completing the check.
(7) Disconnect charging hose from gas service valve's service port and fully open liquid and gas opera-
tion valves. (Do not attempt to turn valve rod beyond its stop.)
(8) T ighten service valve caps and service port cap to the specified torque shown in the table below.
Service valve size (mm)
ø6.35 (1/4")
ø9.52 (3/8")
ø12.7 (1/2")
Liquid service valve
Valve cap
Gas service valve
Service port
CAUTION
• To prevent the entering of different oil into the refrigeration system, do not use tools designed for any
other refrigerant type (R22, R407C, etc.).
• To prevent vacuum pump oil from entering into the refrigerant system, use a counterflow prevention adapter.
5. Additional refrigerant charge
Additional refrigerant charge is required only when connecting pipe length exceeds 15 m.
5.1 Calculating additional refrigerant charge
Additional refrigerant charge can be calculated using the formula given below.
Additional refrigerant charge (g) = { Connecting pipe length (m) – Factory charged length 15 (m) } x 20 (g/m)
NOTE
• If additional refrigerant charge calculation result is negative, there is no need to remove the refrigerant.
• If refrigerant recharge is required for the unit with connecting pipe length 15m or shorter, charge the
factory charged volume as shown in the table below.
Factory charged volume(kg)
Conventional
5.2 Charging refrigerant
(1) Charge the R410A refrigerant in liquid phase from service port with both liquid and gas service
1.0-1.5
valves shut. Since R410A refrigerant must be charged in the liquid phase, make sure that refriger-
ant is discharged from the cylinder in the liquid phase all the time.
(2) When it is difficult to charge a required refrigerant volume, fully open both liquid and gas service
valves and charge refrigerant, while running the unit in the cooling mode. When refrigerant is
charged with the unit being run, complete the charge operation within 30 minutes.
(3) Write the additional refrigerant charge calculated from the connecting pipe length on the label at-
tached on the service cover.
CAUTION
Running the unit with an insufficient quantity of refrigerant for a long time can cause unit malfunction.
NOTE
• Consult with our distributor in the area, if you need to recover refrigerant and charge it again.
(2) Clean the existing pipe system according to the procedure given below.
(a) Carry out forced cooling operation of existing unit for 30 minutes.
For 'Forced cooling operation' refer to the indoor unit installation manual.
(b) Stop the indoor fan and carry out forced cooling operation for 3 minutes (Liquid return).
(c) Close the liquid service valve of the outdoor unit and carry out pump down operation (Refer to 6.
PUMP DOWN).
(d) Blow with nitrogen gas. If discolored refrigeration oil or any foreign matter is discharged by the
blow, wash the pipe system or install a new pipe system.
(3) Remove the flare nuts from the existing pipe system. Go back to 4.Connecting Piping work and
proceed to step 2.2 Cutting connecting pipe.
CAUTION
Do not use the old flare nuts (of existing unit). Make sure that the flare nuts supplied with the (new)
outdoor unit are used.
* If the existing piping is specified as liquid pipe ø9.52 or gas pipe ø12.7, refer to the following. (SRC40,50
and 60 only)
<Table of pipe size restrictions>
Additional charge volume per meter of pipe
Liquid pipe
Pipe size
Gas pipe
Maximum one-way pipe length
Length covered without additional charge
Additional charge volume (kg) = {Main pipe length (m) - Length covered without additional
charge shown in the table (m)} X Additional charge volume per meter of pipe shown in the table (kg/m)
32
- -
'17 • SRK-T-203
Service valve cap tightening Service port cap tightening
torque (N·m) torque (N·m)
20-30
10-12
25-35
Compound pressure gauge
Pressure gauge
Gauge manifold
Handle Lo
Handle Hi
Vacuum pump
Charge hose
Model SRC 20/25/35 Model SRC40/50/60
1.45 1.50
0.06kg/m
ø9.52
ø12.7
10
5