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Adjustment during Operation
Adjusting Refrigerant Quantity of the Refrigeration Unit
During determination of refrigerant quantity, temperature setting of all cooling coils of the showcase needs to be set to
the lowest temperature without activation of the thermostat for making the refrigeration unit operating continuously.
(1) Method of determining refrigerant quantity
Check the operating condition of the refrigeration unit and adjust to the correct refrigerant quantity.
1. Set the low pressure according to the Table 1 and Table 2. (Refer to the "Low Pressure Setting" shown in the
"Setting and Indication of the Control PCB".
2. Check that the suction gas temperature is 18 °C or below.
3. Check that the superheat of the suction gas temperature is secured by 10 K or higher.
4. When the showcase and cooling coils are fully cooled, check the superheat of the evaporator outlet
temperature.
Set value of superheat ±2 K is appropriate (6 to 10 K in the case of 8 K setup value)
Table 1 Refrigeration (Refrigerator, vegetable/daily
foods, meat/fi sh)
ON value (MPa)
OFF value (MPa)
This setting is for determining refrigerant quantity. After fi nishing refrigerant quantity determination,
Caution
change the setting of ON value and OFF value according to the purpose of operation. (Refer to the
"Low Pressure Setting" shown in the "Setting and Indication of the Control PCB".
When charging refrigerant while ambient temperature is 25 °C or below, check superheat during summer season.
The guideline of high pressure and intermediate pressure against ambient temperature is as shown in Table 3 and 4.
Ambient temperature can be checked in the back mode 2. (Refer to the "List of Setting and Display" in the "Setting
and Indication of the Control PCB")
Table 3 Refrigeration (Refrigerator, vegetable/daily foods, meat/fi sh)
Ambient temperature (°C)
High pressure (MPa)
Intermediate pressure (MPa)
Table 4 Freezing (Freezer, ice)
Ambient temperature (°C)
High pressure (MPa)
Intermediate pressure (MPa)
Shortage of refrigerant tends to cause lower level of high pressure and higher level of intermediate
Caution
pressure.
Table 2 Freezing (Freezer, ice)
2.96
ON value (MPa)
2.80
OFF value (MPa)
0
5
10
5.2
5.6
6.1
3.8
4.1
4.3
0
5
10
4.2
4.8
5.3
1.8
2.1
2.5
EN - 37
15
20
25
6.5
7.0
7.4
4.5
4.7
4.9
15
20
25
5.9
6.4
6.9
2.8
3.1
3.5
1.52
1.42
30
35
40
7.9
8.3
8.8
5.1
5.4
5.6
30
35
40
7.5
8.0
8.6
3.8
4.1
4.5
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