Mitsubishi Heavy Industries SRK25GZ-L1 Handbook page 721

Models FDC808HES3, 1008HES3
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) Charging with additional refrigerant
The length of piping will require charging with additional refrigerant. Refer to the table below for making the additional charge. If
your calculations show that the additional charge amount is a minus number, charging is not required.
Item
Piping length already
A
charged with refrigerant.
Standard refrigerant volume.
B
(When piping is 0 meters.)
Additional charge volume
C
per 1 meter of main piping.
Amount of charge
D
at time of shipping
Maximum permissible
E
charge volume.
Notes (1) Use the table above to find the amount of additional charge (kg/m)
C per 1 meter of piping.
(2) The value in ( ) indicates the amount of additional charge per 1
meter of piping for main piping up to 30 meters.
Method of Calculation
Refer to the example of calculation on the next page for the piping length code in the formula (L,
For additional charging G = Amount of additional charge (kg.)
Twin and triple specifications
G = main piping L (m) × C + branch piping length
Confirm for additional charge volume (FDC508HES3 only)
• If the calculated required charge is greater than the maximum permissible charge volume shown in the table above, use the
following formula to find the amount of the insufficient refrigerant amount for the weight of the additional charge.
• If the calculated required charge is less than the maximum permissible charge volume shown in the table above as well as greater
than amount of charge at the time of shipment, use the following formula to find the amount of the insufficient refrigerant
amount for the weight of the additional charge.
Amount
FDC508 FDC808 FDC1008
(m) 5 5
(kg) 1.73 5.11
0.02
(kg/m) 0.045
(0.035)
(kg)
1.90 5.33
_
(kg) 3.18
(m) × f + branch piping length
1
G (kg) = E (kg) _ D (kg)
G (kg) = Reguired charge amount (kg) _ D (kg)
Air purge
(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
Gas service valve
¡ f = Additional charge amount per 1 meter of
branch piping
208, 258, 308: 0.025kg/m
5
408, 508: 0.035kg/m
7.25
0.07
7.60
_
(m) × f + branch piping
2
V MULTI
(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).
Open state
, ~ ).
1 3
(m) × f – (D – B)
3
(only for triple specifications)
719