Mitsubishi Heavy Industries SRK25GZ-L1 Handbook page 157

(2) Connection of refrigerant piping
¡ The service valve corresponding to each indoor unit is as illustrated in the right figure.
¡ Regarding the change in the sizes of gas side pipes (usage of the variable joints); if a 3.2/
4.0/5.0 kW class indoor unit (gas side pipe 12.7) is going to be connected to the rooms A
and C service valves (9.52), or if a 2.2-2.8 kW class indoor unit (gas side pipe 9.52) is
going to be connected to the rooms B and D service valves (12.7), variable joints (1, 2)
available as accessories must be applied to the gas side service valves.
[Examples of use of variable diameter joints]
Connection of indoor unit of Class 3.2 to A unit.
Liquid side operational valve (ø6.35)
Operational
valve for room A
Gas side operational
valve (ø9.52)
Copper packing
¡ Securely fit the copper packing between the service valve and the variable diameter joint to prevent shifting.
¡ Cover the pipes with tape so that dust and sand do not enter the pipe until they are connected.
[Connection of pipes]
¡ When connecting the pipes to the outdoor unit, be careful about the discharge of fluorocarbon gas or oil.
¡ Make sure to match the pipes between the indoor unit and the outdoor unit with the correct service valves.
(1) Preparations
Indoor
Push
Remove
¡ Remove the flare nut (from both
liquid and gas sides).
(2) Connection
Indoor
Liquid side
Gas side
¡ Secure the nut with a specified tightening
torque to avoid any gas leaks.
¡ Specified tightening torques are as follows:
Liquid side (ø 6.35): 17mm in width across flat of the flare nut: 15.7-19.6 N·m (1.6-2.0 kgf·m)
Gas side (ø 9.52): 22mm in width across flat of the flare nut: 29.4-39.2 N·m (3.0-4.0 kgf·m)
Gas side (ø 12.7): 24mm in width across flat of the flare nut: 39.2-49.0 N·m (4.0-5.0 kgf·m)
(3) Air purging
To protect the global environment, use a vacuum pump that do not release flourocarbon gas into the atmosphere.
Note: Fully open the service valves (on both liquid and gas sides) after completing air purging
(a) Remove the cap on both gas and liquid sides before starting operation.
(b) After completing the operation, do not forget to tighten the cap (gas may leak).
(c) Conduct air purging for all connected indoor units.
ø6.35 pipe
3.2 kW class
Indoor unit
ø12.7 pipe
Variable diameter joint 2 (ø9.52-ø12.7)
Outdoor
Push
Remove
¡ Remove the flare nut (from both
liquid and gas sides).
Outdoor
Liquid side
¡ Secure the nut with a specified tightening
torque to avoid any gas leaks.
Service valve
for room D
Service valve
for room C
Service valve
for room B
Service valve
for room A
A dimensions
Liquid side: ø 6.35:9 ~9.5dia
Gas side:
A
ø 9.52: 13.2 ~ 14dia
ø 12.7: 16.2 ~ 17dia
¡ Fit the removed flare nut to the joint pipe, and then flare it.
Gas side
¡ When air purging with a vacuum pump,
secure the nut with a specified tightening
torque to avoid any gas leaks.
¡ When air purging with a refrigerant from
an outdoor unit, just temporarily secure the
nut.
SCM-HG (4 room)
Earth screw
ø12.7
ø9.52
ø12.7
ø9.52
Liquid Gas
Liquid Gas
side side
service service
valve valve
155