In addition, Ø12.7 equivalent pipe length is calculated to confirm that the refrigerant charge quantity is smaller than the maximum
refrigerant charge quantity.
Ø12.7 equivalent pipe length = Piping refrigerant quantity (ℓ)/0.098 = 23.6 (m) ……………………………… (b)
Calculate the refrigerant charge quantity for when total capacity of connected unit coolers is 16 (ℓ).
Refrigerant charge quantity = 10.2 (kg) + 16 (ℓ) x 0.2 (kg/ℓ) + 2.3 (kg) = 15.7 (kg) ……………………………… (c)
There is the relationship as shown by Fig. 28 among the Ø12.7 equivalent pipe length (b), refrigerant charge quantity (c) and maximum
refrigerant charge quantity. Since the refrigerant charge quantity: 15.7 kg is smaller than the maximum refrigerant quantity: 17.9 kg, 15.7
kg is taken as the refrigerant charge quantity. (When Calculated refrigerant charge quantity
≥
Maximum refrigerant quantity, charge in the
maximum refrigerant quantity.)
15
5
10
20
25
30
0
20
40
60
80
100
23.6m
17.9kg
15.7kg
M
aximum r
efr
iger
an
t char
ge quan
tit
y (kg)
φ12.7 equivalent pipe length (m)
5.6.6 Refrigerant charge to stopped compressor
• Charge liquid refrigerant from the medium pressure service port of vessel unit.
• When the unit is energized, turn off the unit’s power supply. Turn the dip switch SW5-7 to ON (Up) and turn ON the unit’s power supply.
Electronic expansion valves and solenoid valves (SVHG1, SV-OIL1-2, SV-INJ1, EEVG, EEVSC and EEV-LB1) in the unit open. When the work
is over, turn the dip switch SW5-7 to OFF (Down).
5.6.7 Refrigerant charge in the cycle when the compressor is running
• While the compressor is running, charge liquid refrigerant from the low pressure side service port. Open the valve on the bomb gradually
after operating the compressor. (Don’t open the valve quickly. It could cause liquid back, resulting in failures on the unit.)
Note:
Overcharge of refrigerant could cause the liquid back from the medium pressure receiver. While the condensing unit is operating, take care to
avoid the degree of superheat of under-dome (under-dome temperature - saturation temperature of medium pressure sensor) becomes lower
than 10 deg.
5. System design recommendations
Fig. 28
41
AB408540130380en-000102
© Danfoss | Climate Solutions | 2023.02
Application Guidelines
