Toshiba RAS-18N3KV-E Service Manual page 61

Imperial (wing nut type)
Outer dia. of copper pipe
∅ 6.35
CAUTION
∅ 12.70
<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.
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
∅6.35
∅12.70
<Tightening orque of flare pipe connections>
The operating oressure of R410A is higher than that
of R22 (approx. 1.6 times). It is therefore necessary
to firmly tighten the flare 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.
Flare at indoor unit side
Fig. 10-4-6
R410A
1.5 to 2.0
2.0 to 2.5
Flare nut
Internally
threaded side
Use a torque wrench
to secure.
(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
10-4-4. 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 the air conditioner,
which use R410A, refrigeration cycle trouble may happen.)
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
(For R410A only)
Connecting pipe
Service port
(Valve core (Setting pin))
Packed valve at liquid side
– 60 –
FILE NO. SVM-12071
Pressure gauge
Manifold valve
Handle Hi
(Keep full closed)
Charge hose
(For R410A only)
Vacuum pump
adapter for
counter-flow
prevention
(For R410A only)
Vacuum
pump
Packed valve at gas side
Fig. 10-4-7