Oils for refrigerant R744 (CO2)

Characterising the oils

Bitzer oils for R744

Oil

Oil type

Applications

Designation on compressor

BSE60K

polyolester oil (POE)

standard oil charge for subcritical (e.g. cascade) applications

"K" (e.g. 4DSL‑10K)

BSE85K

polyolester oil (POE)

standard oil charge for transcritical applications,
alternative oil charge for subcritical (e.g. booster) applications

"K" (e.g. 4FTE‑30K)

BSG68K

polyalkylene glycol oil (PAG)

standard oil charge and precondition fo applications with low pressure > 40 bar / high pressure > 120 bar,
alternative oil charge for sub- and transcritical compressors in booster applications e.g. with ejectors

"Z" (e.g. 4MTEU‑10LZ)

Material safety data sheets

Apart from this document, please observe the material safety data sheet (MSDS) for the respective oil. It contains information on toxicity, handling, personal protective equipment and disposal of the oil. Material safety data sheets for all Bitzer oils are available on request.

Application range

Application range of oils for R744 in Bitzer reciprocating compressors. For application limits see also Bitzer Software.
(✔): after consultation with Bitzer Application Engineering
✔*: BSG68K is precondition for applications with low pressure > 40 bar / high pressure > 120 bar

Oil

Air conditioning

Medium temperature application

Low temperature application

BSE60K

– –

– –

✔

BSE85K

(✔)

✔

✔

BSG68K

✔*

✔

✔

Technical data

Overview of the technical data of BITZER refrigeration compressor oils.
The density can be linearly interpolated between the specified values.

Oil

Type

Flash-point (°C)

Pour point (°C)

Density (g/ml)

Kinematic viscosity (cSt)

Specific heat capacity (kJ/kg*K)

Thermal conductivity (W/m*K)

at -30°C

at 15°C

at 100°C

at 20°C

at 40°C

at 100°C

at 40°C

at 100°C

at 40°C

at 100°C

BSE55/ BSE60K

POE

280

-51

1.045

1.010

0.948

147

55

9

1.92

2.09

0.15

0.14

BSE85K

POE

246

-42

1.025

0.993

0.930

200

80

11

1.89

2.05

0.14

0.13

BSG68K

PAG

>200

-46

1.039

1.003

0.937

159

68

16

Miscibility gaps

Miscibility gaps for R744: Limit temperature depending on oil content (mass % of oil in oil refrigerant blend).M: Range of complete miscibility.P: Phase separation range (miscibility gap).
Miscibility gaps for R744: Limit temperature depending on oil content (mass % of oil in oil refrigerant blend).
M: Range of complete miscibility.
P: Phase separation range (miscibility gap).

Refrigerant solubility in oil

The following diagrams can be used to read off the refrigerant content in the lubricant depending on refrigerant pressure and oil temperature.

Oils for R744: Refrigerant pressure depending on the oil temperature and the refrigerant content (mass % of refrigerant in oil-refrigerant blend).
Oils for R744: Refrigerant pressure depending on the oil temperature and the refrigerant content (mass % of refrigerant in oil-refrigerant blend).

Warning values for used oils

The listed oils are categorized as group KB according to DIN51503-1. To determine the used condition of the oil, e.g. with respect to water content or total acid number (TAN), the reference values of DIN 51503-2, apply.

Warning values for used Bitzer oils for R744.
(*): that is ± 15% of the value for new oil

Oil

Kinematic viscosity at 40°C (DIN EN ISO3104)

Max. water content
(DIN51777)

Total acid number
(DIN ISO6618)

BSE60K

outside of 47 .. 63 cSt (*)

150 mg H2O/kg oil

0.2 mg KOH/g

BSE85K

outside of 68 .. 92 cSt (*)

150 mg H2O/kg oil

0.2 mg KOH/g

BSG68K

outside of 58 .. 78 cSt (*)

800 mg H2O/kg oil

0.2 mg KOH/g

Elastomer compatibility

Relevant literature recommends the following seaI materials for polyolester oils (POE) and polyalkylene glycol oils (PAG) with R744: