Emerson Copeland EazyCool OME-4MTL-09X, Application Manuallines, Page: 11 / 71

6 C6.1.11/0718-0619/E
2.6 Application range
2.6.1 Qualified refrigerant and oil
Oil recharge values can be taken from Copeland brand products Select software available at
www.climate.emerson.com/en-gb .
Qualified
refrigerant
R744 (CO
2
)
Qualified
servicing oil
Polyolester Emkarate RL 68 HB
Oil charge
in litres
OME-4MTL-05X OME-4MTL-07X OME-4MTL-09X
1.5 1.5 1.5
Table 3: Qualified refrigerant and oil
NOTE: Use only lubricants that are qualified for the product. The use of non-approved
lubricants can damage the product and will result in loss of warranty!
NOTE: The polyolester oil is very hygroscopic. Never keep the system open to the ambient. If
for any reason there is no refrigerant in the system, it is recommended to charge the system
with a protective gas, eg, inert gas N
2
.
The r
ecommended quality for carbon dioxide purity class is 4.0 [(≥ 99.99%) H
2
O ≤ 10 ppm,
O
2
≤ 10 ppm, N
2
≤ 50 ppm] or higher.
The characterization of R744 (CO
2
) according to EN 378-1 is safety class A1, not flammable,
ODP = 0 and GWP = 1. High concentrations of CO
2
are dangerous. This refrigerant is odourless and
colourless. Therefore the use of CO
2
detectors is required.
CO
2
is heavier than air. As a result, local concentrations (especially at floor level or in deeper slots =
CO
2
pockets) can be higher than average values in the machine room. The ventilation system must
take this into account.
2.6.2 Application limits
WARNING
Oil dilution due to low superheat! Compressor breakdown!
Low suction
superheat leads to oil dilution. Always operate the system with adequate
superheat to avoid oil viscosity decrease. Additional measures in system
design might help to avoid unacceptable lubrication conditions.
For the application envelope, please refer to Select software at www.climate.emerson.com/en-gb .
2.6.3 Recommendations for minimum suction superheat
– Lubrication conditions
The operation of CO
2
compressors / units at conditions where the viscosity of the oil is low might
become very harmful with regard to compressor lifetime expectancy. Indicators like oil temperature
and discharge temperature must be observed to judge about the lubrication conditions. Depending
on the application (low temp, medium temp, parallel compression, etc.…) different minimum suction
superheat values should be respected to secure maximum protection of the compressor. In general,
higher superheat on the suction inlet of a compressor provides higher safety, but the limits for the
maximum allowable discharge temperature should be considered as well (superheat has a direct
impact on discharge temperature). For medium temperature applications, an absolute minimum of
10K is recommended.
Particular attention should be paid to the following points:
▪
Measuring the suction superheat becomes more critical with larger diameters on the suction
tube. Ensure proper positioning of sensor. Sensor sleeves must be used with large diameters.
▪
The oil temperature is measured by the dedicated unit sensor and can be read out from the
Visograph display in the service menu.
▪
The discharge temperature is observed by the unit controller. The temperature on the discharge
line should never exceed 135°C (measured directly after the compressor shut-off valve). The
temperature of the discharge gas on the outlet of the valve plate is 10-15K higher than the
temperature on the discharge line.