Toshiba RAS-25J2KVSG-ND Service Manual page 72

<Tightening connection>
Align the centers of the connecting pipes and tighten
the flare nut as far as possible with your fingers
tighten the nut with a spanner and torque wrench as
shown in the figure.
Half union
Externally
threaded side
Use a wrench to secure.
Fig. 10-4-5
CAUTION
Do not apply excess torque. Otherwise,
the nut may crack depending on the conditions.
Outer dia. of copper pipe
Ø6.35 mm
Ø9.52 mm
Ø12.70 mm
Tightening torque of flare pipe connections
The operating pressure of R32 is higher than that
of R22 (approx.1.6 times). It is therefore necessary
to firmly tighten the fl are pipe connecting sections
(which connect the indoor and outdoor units) up to the
specified tightening torque. Incorrect connections may
cause not only a gas leakage, but also damage to the
refrigeration cycle.
Fig. 10-4-6
. Then
Flare nut
Internally
threaded side
Use a torque wrench to tighten.
(Unit : N•m)
Tightening torque
16 to 18 (1.6 to 1.8 kgf•m)
30 to 42 (3.0 to 4.2 kgf•m)
50 to 62 (5.0 to 6.2 kgf•m)
Flare at
indoor unit side
Flare at
outdoor unit side
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 a 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 oil inside of the vacuum pump
enters into the air conditioner, which use R32,
refrigeration cycle trouble may result.)
1. Connect the charge hose from the manifold valve
to the service port of the packed valve at gas side.
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 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 the
gauge manifold valve.
6. Open fully the valve stem of the packed valves
(both gas and liquid sides).
7. Remove the charging hose from the service port.
8. Securely tighten the caps on the packed valves.
Compound pressure gauge
–101 kPa
(–76 cmHg)
Handle Lo
Charge hose
Connecting pipe
Service port (Valve core (Setting pin))
Packed valve at liquid side
- 72 -
Pressure gauge
Manifold valve
Handle Hi
(Keep full closed)
Charge hose
Vacuum pump adapter for
counter-f ow prevention
Vacuum
pump
Packed valve at gas side
Fig. 10-4-7