VRF Air-Conditioner IOM
4
system shall not be more than 15.
The bending radius of curve shall be larger than
10cm.
Pinch off evaporator process pipe with pincers
before connecting pipe, discharge the gas in the
evaporator, and then twist the evaporator union
nut with a spanner.
Coat a layer of sealing oil at joint and horn
mouth before connecting pipe.
When connecting and dismantling piping to/from
air conditioner, simultaneously use an ordinary
spanner and a torque spanner.
Figure 9 Piping Connection Diagram
For relevant tightening torque, please refer to
Table 1.
Table 1
Pipe diameter
Tightening torque
(N.m)
φ6.35(1/4")
14.2~17.2
φ9.53(3/8")
32.7~39.9
φ12.7(1/2")
49.5~60.3
φ15.88(5/8")
61.8~75.4
Excessive tightening may damage horn mouth
and lead to refrigerant leakage.
Indoor unit inside has gas with a certain pressure,
so do not directly loose nut to discharge gas in
order to avoid personnel injury; please do not
overexert in order to avoid damaging the flaring.
9.
Air Tightness Leakage Detection
Conduct
air
tightness
leakage
detection
confirmation at the end of piping work.
Leakage detection method:
(a)
Fill dry compressed nitrogen into indoor unit
and piping system, and slowly boost the
pressure to 4.3MPa;
(b)
After maintaining pressure for 10min, coat
soapy water or other foaming agent at the
connection position such as weld and thread
joint, and observe whether there is leakage;
(c)
If any leakage, tighten or repair weld leaking
position after pressure relief.
(d)
Fill into dry compressed nitrogen again and
slowly boost the pressure to 4.3MPa;
(e)
Start to record the reading of pressure gauge
after maintaining pressure for 6h, and then
record the reading of pressure gauge again after
24h;
(f)
If no pressure drop, then the air tightness is
qualified. If any pressure drop, find out the
leakage point and repair, and then repeat the
above d and e procedures until qualified.
Pressure reading is related to temperature
variation, so the temperature variation factor
shall be considered when judging whether there
is pressure drop. The relation of pressure
correction value and temperature variation is:
−
+
+
∗
=
∆
1
273
273
1
2
1
t
t
P
P
P
P
P
∆
−
=
2
correction
△
P--Pressure correction value (bar)
P
correction
---Corrected pressure value (bar)
P
1
---The first pressure reading (bar)
P
2
---The second pressure reading (bar)
t
1
---Temperature at the first pressure reading
(
)
℃
t
2
---Temperature at the second pressure reading
(
)
℃
In air tightness test, do not connect indoor unit
and outdoor unit, otherwise, nitrogen may leak to
outdoor unit.
10.
Thermal Insulation
If no leakage after inspection, respectively wrap
liquid pipe, gas pipe and each connecting
position
with
thick-enough
heat-resistant
Caution
Caution
Evaporator
process
pipe
