SmartCool
TM
- D
Precision Air Conditioning
20
Precision Air Conditioning
Installation, Maintenance and Commissioning Manual :6877419 02/2013
Liquid Line Refrigerant
Charge (kg/m)
The following table shows the refrigerant charge / metre for the liquid line, using R410A
and assuming a liquid line temperature of 40°C.
Liquid Line (m)
kg/m
3/8”
0.05
1/2”
0.09
5/8”
0.15
3/4”
0.21
7/8”
0.30
1 1/8”
0.53
IMPORTANT
The pipe sizes/refrigerant charges quoted are for guidance only. It is the responsibility of
the installing contractor/site engineer to check the pipe sizes/refrigerant charges are correct
for each system installation and application. Excess pressure drop on a system may require
additional refrigerant charges to ensure correct unit operation.
Split systems may require additional oil which should be added to the low side of
each compressor.
Design should be in accordance with accepted refrigeration practice to ensure good oil
return to the compressor(s) under all normal operating conditions.
Calculation of Liquid Line
Refrigerant Charge (kg)
The liquid line refrigerant charge can be calculated using the following equation:
LR = L x m
Where:
LR = Total Liquid Line Refrigerant charge (kg)
L
= Length of Interconnecting pipework (metres)
m
= Liquid Line Refrigerant charge / metre. Refer to
Liquid Line Refrigerant
Charge (kg/m), above.
Calculation of System
Refrigerant Charge (kg)
The system refrigerant charge can be calculated using the following equation:
SR = LR + IR + OR
Where:
SR = Total System Refrigerant charge (kg)
LR = Total Liquid Line Refrigerant charge. (As calculated from above)
IR
= Indoor Unit Refrigerant Charge.
OR = Outdoor Unit Refrigerant Charge.
Example
Indoor Unit Model Ref.
= SC19D055-X2X2-0
Outdoor Unit Model Ref.
= CR50 Condenser
Interconnecting Pipework
= 10 metres
Selecting The Liquid Line Size
From the
Refrigerant Pipe Sizing Guide
, the liquid line size given for pipework length of 10 metres
is:
Liquid Line Size
= 5/8”
Liquid Line Refrigerant
Charge
LR = L x m
Where:
L
= 10 metres
m
= 0.15 kg/m
LR = 10 x 0.15
Liquid Line Charge = 1.5 kg
System Refrigerant Charge
SR = LR + IR + OR
Where:
LR
= 1.5 kg. (As calculated from above)
IR
= 4.41 kg
OR = 4.9 kg
SR = 1.5 + 5.57 + 4.9
System Refrigerant Charge = 10.81kg / Circuit
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