Design and Technical Manual

6. SYSTEM DESIGN
CHECKING CONCENTRATION LIMIT11-2.
Check concentration limit following steps

, and take appropriate measures depending on
the situation.

Calculate amount of refrigerant [lbs. (kg)] per refrigerant system.
Amount of refrigerant per
refrigerant system
Amount of additional
refrigerant
Total amount of refrigerant in
system (lbs, kg)
+ =
Amount of factory
charged refrigerant
Amount of refrigerant
added to system based
on pipe length, pipe size
and indoor units.
Note: When one refrigerant
system is divided into 2 or more
refrigerant systems and each
system is independent, total
amount of refrigerant of each
system shall be adopted.

Smallest room volume.
Calculate room volume by regarding portion as one room or the smallest room.

Calculate refrigerant concentration from the results of

and

(a) Without partition
Outdoor unit
Branch box
Indoor unit
Outdoor unit
Indoor unit
Partition
Opening
(b) When there are partitions,
but there is an effective
opening for ventilation
between the rooms.
Branch box
Outdoor unit
Indoor unit
Small
est
room
(c) With partition and without
opening which serve as
passage of air to adjoining
room.
Branch box
When the result of calculation
exceeds the limiting concentration,
perform the same calculations by
shifting to the second smallest,
and the third smallest rooms until
the nal result is below the limiting
concentration.
≤Refrigerant concentration [lb/Mcf (kg/m
3
)]
(R410A)
Total amount of refrigerant in
refrigerant system (lbs,kg)
Capacity of smallest room
where indoor unit is installed
[cf (m
3
)]
- (06 - 141) -
SYSTEM DESIGN SYSTEM DESIGN