Mitsubishi Heavy Industries SRK25GZ-L1 Handbook page 343

¡ Take care so that the piping to be worked does not contact the parts contained in the unit.
IMPORTANT
If it contacts the inner parts, abnormal sound or vibration may occur.
(c) Leak test and air purge
Perform the procedure according to the following instructions.
¡ Perform the air purge of Indoor unit and refrigerant piping by vacuuming method without fail.
Request
Models FDC(P)208~508 type
Leak test
1) After tightening all flared nuts on the Indoor
unit and Outdoor unit, hold the service valves
(both of liquid and gas sides) of the Outdoor
unit in fully closed position and perform the
leak test from the charge port of service valve
to confirm that there is no leakage.
(
Use nitrogen gas for leak test. Execute
the test at the pressure of 3.0 MPa.
Hexagonal Head Wrench
(Size 4)
Open
FDC(P)208, 258, 308 Liquid / gas service valve
FDC(P)408, 508
Models FDC808, 1008 type
Leak test
(1) The unit's air-tightness test has been conducted but after completing
the piping connections conduct an air-tightness test of the connected
piping and the indoor units using the outdoor gas side service valve
check joint. Be sure to conduct this test with the service valve closed.
1 When the pressure has been increased to 0.5 MPa stop increasing
the pressure and maintain this state for at least 5 min. to check if
the pressure drops.
2 Next, increase the pressure to 1.5 MPa and again maintain this
state for at least 5 min. to check if the pressure drops.
3 Then increase the pressure to 3.0 MPa and maintain this state for
approx. one day to check if the pressure drops.
Use nitrogen gas for the air-tightness check.
Hexagonal Head Wrench
(Size 4)
Open
Liquid service valve
(d) Heat insulation for refrigerant piping
(i) The gas piping and liquid piping must be insulated
against heat and condensation by heat insulation
material.
1) Condensation can form on the gas line during cooling op-
eration and drain off, causing leakage problems. Also,
people can be burned by the high temperatures on the sur-
face of the piping due to the flow of discharge gas during
heating. To prevent this, the piping should be wrapped in
insulating material.
2) Insulate the flare connection sections of the indoor unit
with insulating material (pipe covering). (Perform this
for both gas and liquid lines.)
3) Wrap the gas and liquid piping with insulation, making
sure that no gaps can form inside. Bundle the piping and
wires together and wrap with exterior tape.
Air purge
2) While holding the service
valves (both of liquid and gas
sides) of the Outdoor unit at
f u l l y c l o s e d p o s i t i o n ,
perform vacuuming at –0.1
MPa (–76 cmHg) or under
from the service valve charge
)
port.
Liquid service valve
3) After completion of vacuuming,
remove the cap nut for the valve
stem and fully open the service
valve (for both of liquid and gas)
as shown in the right illustration.
After confirming that the valve is
fully open, tighten the cap nuts (for
valve stem and charge port).
Handle
Pin
Open state
FDC(P)408,508
Gas service valve
Air purge
(3) After completion of
(2) While holding the
service valves (both
of liquid and gas
sides) of the Outdoor
unit at fully closed
position, perform
vacuuming at –0.1
MPa (–76 cmHg) or
under from the servi-
ce valve charge port.
Handle
Pin
Open state
Gas service valve
Indoor/outdoor
connection wire
Liquid piping
Use a material with good heat transfer resistance
qualities (120 °C or more)
FDT ( N ) -H
vacuuming, remove the
cap nut for the valve
stem and fully open the
service valve (for both
of liquid and gas) as
shown in the right
illustration.
After confirming that
the valve is fully open,
tighten the cap nuts (for
valve stem and charge
port).
Exterior tape
Gas piping
Insulating material
341