Toshiba RAS-18UFHP-ES Service Manual page 43

<Tightening connection>
Align the centers of the connecting pipes and tighten
the flare nut as far as possible with your fingers. Then
tighten the nut with a spanner and torque wrench as
shown in the figure.
CAUTION
• Do not apply excess torque, otherwise the nut
may crack depending on the conditions.
Outer dia.
of copper pipe
∅6.35 mm
∅12.70 mm
• Tightening torque of flare pipe connections
The operating pressure of R-410A is higher than that
of R-22 (Approx. 1.6 times). It is therefore necessary to
tighten firmly flare pipe connecting sections (which
connect the indoor and outdoor units) up to the
specified tightening torque. Incorrect connections may
not only cause a gas leakage, but also damage the
refrigerant cycle.
Fig. 8-5-4
Half union
Externally
threaded side
Use a wrench to secure.
Fig. 8-5-5
CAUTION
• KEEP IMPORTANT 4 POINTS FOR PIPING
WORK
(1) Take away dust and moisture (Inside of the
connecting pipes).
(2) Tight connection (between pipes and unit).
(3) Evacuate the air in the connecting pipes using
VACUUM PUMP.
(4) Check gas leak (connected points).
(Unit : N·m)
Tightening torque
16 to 18 (1.6 to 1.8 kgf·m)
50 to 62 (5.0 to 6.2 kgf·m)
Flare at
outdoor unit side
Flare nut
Internally
threaded side
Use a torque wrench to tighten.
8-5-3. Evacuating
After the piping has been connected to the indoor unit,
you can perform the air purge together at once.
AIR PURGE
Evacuate the air in the connecting pipes and in
the indoor unit using vacuum pump. Do not use the
refrigerant in the outdoor unit.
For details, see the manual of the vacuum pump.
<Using a vacuum pump>
Be sure to use a vacuum pump with counter-flow
prevention function so that inside oil of the pump does
not flow backward into pipes of the air conditioner
when the pump stops. (If inside oil of the vacuum pump
enters into the air conditioner which adopts R-410A, a
trouble of the refrigeration cycle may be caused.)
1. Connect the charge hose from the manifold valve to
the service port of the gas side packed valve.
2. Connect the charge hose to the port of the vacuum
pump.
3. Open fully the low pressure side handle of the
gauge manifold valve.
4. Operate the vacuum pump to start for evacuating.
Perform evacuating for about 15 minutes if the
piping length is 20 meters. (15 minutes for 20
meters) (Assuming a pump capacity of 27 liters per
minute.) Then confirm that the compound pressure
gauge reading is –101 kPa (–76 cmHg).
5. Close the low pressure side valve handle of gauge
manifold.
6. Open fully the valve stem of the packed valves (both
sides of Gas and Liquid).
7. Remove the charging hose from the service port.
8. Securely tighten the caps on the packed valves.
Compound pressure gauge
-101kPa (-76cmHg)
Handle Lo
Charge hose
(For R-410A only)
Connecting pipe
– 42 –
FILE NO. SVM-02009
Pressure gauge
Manifold valve
Handle Hi
(Keep full closed)
Charge hose
(For R-410A only)
Vacuum pump
adapter for
counter-flow
prevention
(For R-410A only)
Vacuum
pump
Packed valve at gas side
Service port
(Valve core (Setting pin))
Packed valve at liquid side
Fig. 8-5-6