Coolex N Product description
Product data sheet
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Coolex® N

Heat transfer fluid based on monoethylene glycol (MEG), offering protection against frost and corrosion in technical systems.

Brief description
  • Red colored
  • Corrosion inhibitor/antifreeze concentrate to be diluted with water
  • Permanent usage temperature: approx. -35 to +150 °C
  • Nitrite-, nitrate-, amine-, silicate-, borate-, phosphate- and heavy metal free
  • Minimum usage concentration 20 % v/v
  • Free of CMR substances (carcinogenic, mutagenic, reprotoxic), e.g. borate
  • Water hazard class: WGK 1 (slightly water polluting)
  • Readily biodegradable and environmentally friendly
  • Long-living product (OAT product; organic acid technology)
  • Not suitable for food-related and pharmaceutical applications (→ Coolex® L)
  • Non-regulated according to ADR/GGVE/GGVSEB
Product description
Coolex® N is a red colored corrosion inhibitor and antifreeze concentrate based on monoethylene glycol. It protects the circuits in technical systems – even in mixed installations – against frost and corrosion. The heat transfer fluid is formulated free of CMR substances as well as nitrite, nitrate, amine, silicate, borate and phosphate. Additionally, it prevents the circuit from scaling.
Coolex® N is universally applicable in many installations, such as:
- Heating and cooling systems
- Hot water heating circuits
- Heat pumps
- Geothermal energy
- Heat recovery systems
- Air conditioning
Etc.

Coolex® N is not suitable for use as a radiator antifreeze.
The corrosion inhibitors in Coolex® N protect the whole heating or cooling circuit sustainably from corrosion.
Coolex® N must always be mixed homogeneously with water (see also at frost protection and usage notes).
Physical parameters
Parameter Unit Value Standard
Density (20 ° C) g/cm³ approx. 1.112 DIN 51757
Refractive index nD20 --- approx. 1.431 DIN 51423
pH value, 1: 2 in water --- approx. 8.0 DIN 51369
Reserve alkalinity ml 0,1 M HCl approx. 4.5 ASTM D 1121
Boiling point (1,013 mbar) °C approx. 160 ASTM D 1120
Kinematic viscosity (20 ° C) mm²/s approx. 22.7 DIN 51562-1
Specific heat (20 ° C) kJ / (kg*K) approx. 2.40 --- (calculated)
Thermal conductivity (20 ° C) W/(m*K) approx. 0.29 --- (calculated)
Specific electrical conductivity (25 ° C), 1: 2 in water uS/cm approx. 2,350 DIN EN 27888
Corrosion protection
The inhibitor system in Coolex® N protects all common used metals in technical systems effectively and sustainably from corrosion.
The following table shows the corrosion perfomance (weight loss in g / m²) according to ASTM D 1384¹.
Material Coolex® N 20 % v/v Coolex® N 33 % v/v Pure MEG² without inhibitors 33 % v/v ASTM Limit at 33 % v/v
copper -0.2 -0.2 -2.6 -3.6
Soft solder -0.4 -0.1 -143 -10.9
Brass -0.4 -0.3 -7.2 -3.6
Steel -0.5 -0.2 -158 -3.6
Cast iron ±0 ±0 -285 -3.3
Cast aluminium -1.6 -0.6 -19 -10.0
¹ Modified ASTM D 1384 test: Instead of using the standard ASTM concentration of 33 % v/v, the usage concentration was reduced to a minimum of 20 % v/v. The reduced concentration intensifies the standard significantly.
The analyses were executed by an independent, certified and accredited laboratory.
The abbreviation „ASTM“ stands for „American Society for Testing and Materials“.
² For comparison.
³ The limits for the maximum acceptable weight changes are given according to the standard ASTM D 3306.
Frost protection and general information
Basically, Coolex® N can be diluted with water in any concentration. Though, the minimum usage concentration of 20 % v/v must not be lowered. The desired frost protection can be adjusted by means of the following table.
Coolex® N should be used as a mixture with water only. The minimum usage concentration of Coolex® N is 20 % v/v. This concentration represents a frost protection (= crystallization point) of approx. -9 °C.
Usage concentrations and frost protection:
Frost protection
Coolex® N/water mixture Concentration of Coolex® N % m/m Crystallization point (ASTM D 1177) Solidifying point (DIN ISO 3016) Density [g / cm³]
20 % v/v 21.78 approx. -9 °C approx. -12°C approx. 1.027
27 % v/v 29.18 approx. -14 °C approx. -18 °C approx. 1.038
30 % v/v 32.32 approx. -16 °C approx. -20 °C approx. 1.042
34 % v/v 36.47 approx. -19 °C approx. -24 °C approx. 1.047
39 % v/v 41.60 approx. -24 °C approx. -30 °C approx. 1.054
44 % v/v 46.68 approx. -29 °C approx. -35 ° C approx. 1.060
50 % v/v 52.70 approx. -36 °C approx. -43 ° C approx. 1.068
Mixtures with Coolex® N concentrations above 60 % v/v are not reasonable since the frost protection is decreasing at concentrations higher than 60 % v/v (exceeding the Eutectic Point of the mixture).

The frost resistance of Coolex® N/water mixtures can be determined with an antifreeze tester or a refractometer.
Both instruments can be obtained at Coolex Chemie GmbH – please contact us!
Application fields
Coolex® N/water mixtures are universally applicable in all common heating and cooling systems like heat pumps, air conditioning or warm water heating systems, heat recovery or geothermal systems as well as a heat transfer medium in industrial production plants.
Coolex® N is not suitable for any food-related or pharmaceutical application. Alternatively, Coolex® L is recommended.
Application notes
  • Coolex® N must be always diluted with water homogeneously. Homogeneous Coolex® N/water mixtures do not seperate anymore – even after years of application.
  • For diluting Coolex® N only water with a chloride concentration below 100 ppm must be used. Ideally, de-ionized water is used only. Factory-made Coolex® N/water mixtures are made with de-ionized water only – to offer optimal water quality.
  • The minimum usage concentration of Coolex® N/water mixtures is 20 % v/v. This represents a frost resistance (crystallization point) of approx. -9 °C.
  • Due to the danger of bacterial growth and microbial induced corrosion, the minimum usage concentration should not fall short.
  • The frost resistances relating to each specific application can be found in the table „usage concentrations and frost protection“.
  • Since Coolex® N/water mixtures are based on glycol, they show a much lower surface tension than pure water. This may lead to a dissolution of existing rust layers if an old system is topped up with the heat transfer fluid. Thus, old systems should be flushed with water until they are rust-free. In particular cases, sufficient cleaning of the old system by pickling may be necessary. Coolex® N/water mixtures should be filled only in clean systems without rust damages.                  Please note: Due to their huge surface, fine residues of rust can lead to an early waste of the corrosion inhibitors.
  • Zinc-coated (galvanized) pipes should be avoided in the installation. Glycol/water mixtures dissolve the zinc surface and lead to both elemental zinc and – as a result of its reaction with glycol – zinc glycolates. This does not affect the corrosion performance of Coolex® N since the corrosion inhibitors will protect the steel surface under the zinc layer. However, zinc and/or zinc glycolates may settle at the mechanical seal of the circulating pump and damage it, which may eventually lead to a leakage. In order to get rid of the deposits, a fine filter can be installed and cleaned regularly (e.g. in a bypass). In practice a mesh size of 100 to 150 µm proved to be adequate for this application.
  • Before initial filling of the heating or cooling circuit all parts of the system must be cleaned thoroughly (e.g. flushing). Rust and tinder must be removed.
  • Temporarily emptied systems should be refilled as soon as possible (within a few days) in order to prevent a possible corrosion damage.
  • Because Coolex® N/water mixtures have a much higher viscosity than pure water, the pressure drop in the system pipes must be taken into account. Specific data can be provided at request.
  • Please note: Pure glycol/water mixtures without corrosion inhibitors should not to be used since these fluids are more corrosive than pure water.
Material compatibility
The following table⁴ lists all plastics and elastomers which are compatible with Coolex® N/water mixtures:
Nitrile rubber NBR Polyamide PA (up to approx. 110 ° C) ⁵
Olefin rubber EPDM Silicone rubber And
Natural rubber NR Polypropylene PP
Styrene-butadiene rubber SBR (up to approx. 100 ° C) ⁵ Fluorocarbon elastomers FKM
Polyethylene (low and high density) LD-PE, HD-PE Acrylonitrile butadiene styrene ABS
Polytetrafluoroethylene PTFE Polyester resins UP
Polyvinylchloride (hard) PVC, h Polyacetal POM
⁴ All plastics and elastomers have been tested at a temperature of 80 ° C. Please also note the manufacturer's instructions for the elastomers.
⁵ Literature values.
Additionally, hemp and PTFE tapes are suitable for pipe thread sealing as well.
Packagings
Standardly, Coolex® N (concentrate) is available in polyethylene containers, steel drums, IBC’s (Intermediate Bulk Containers) and road tankers:
Packaging PE container PE container PE container PE container Steel drum IBC Road tanker
Packing content 10 liters 20 liters 30 liters 60 liters 216 liters 1.000 liters 23.000 kg
Fill weight Coolex® N (concentrate) 10 kg (ON REQUEST) 20 kg (ON REQUEST) 30 kg 60 kg 230 kg 1.100 kg 10,000 to 23,000 kg
Coolex® N/water mixtures are available in IBC’s (1,000 liters) or road tankers (min. 10,000 kg).
Ecology and toxicology
Coolex® N does not contain any toxic inhibitors and has a good biodegradability. Due to its MEG base, Coolex® N is rated as „H302: Harmful if swallowed and H373: May cause kidney disease through prolonged or repeated exposure“.
Additionally, the product is labeled with the GHS07 and GHS08 pictograms.
This labeling is valid even for the corresponding water mixtures.
According to VwVwS, both Coolex® N concentrate and its corresponding water mixtures are rated as WGK 1 (slightly water polluting). For more details, please consult the corresponding safety data sheets.
Special/Miscellaneous
  • WGK: Both the concentrate and the corresponding water mixtures of Coolex® N are classified in water hazard class 1 (slightly water polluting). Coolex® N is environmentally friendly and good biodegradable.
  • CMR-free formulation: Coolex® N does not contain any CMR substances (cancerogenic, mutagenic and reprotoxic effects).
  • RoHS: The Coolex® N formulation does not contain any substances which are restricted according to EU Directive 2011/65/EU (lead, mercury, cadmium, chromium, chrome (VI), polybrominated biphenyl, polybrominated diphenyl ether).
  • Coolex® N is a modern, long-living heat transfer fluid based on Organic Acid Technology (OAT) with extreme long change intervals.
  • REACH (Registration, Evaluation, Authorization and Restriction of Chemicals): All substances in Coolex® N are registered or pre-registered according to EC Regulation No. 1907/2006.
  • Coolex® N is also suitable as an additive according to VDI 2035.
Physical data Coolex® N
Crystallization point [° C] Concentration [% v/v] Concentration [% m/m] Temperature [°C] Density [kg/m³] Kinematic viscosity [mm²/s] Specific heat [kJ / (kg * K)] Cubic expansion coefficient [*10-6/K]
-9 20 21.78 -5 1034 4.3 3.78 264
0 1033 3.4 3.78 290
10 1030 2.4 3.79 340
20 1028 1.8 3.80 388
40 1019 1.1 3.83 478
70 1002 0.63 3.90 598
90 988 0.49 3.95 667
-14 27 29.18 -10 1048 6.5 3.63 277
-5 1046 5.0 3.63 303
0 1045 4.1 3.64 326
20 1038 2.1 3.66 418
40 1027 1.3 3.70 502
70 1010 0.70 3.76 615
90 997 0.55 3.81 681
-19 34 36.47 -15 1063 10.0 3.48 310
-10 1061 7.8 3.48 332
-5 1059 6.1 3.49 353
0 1056 4.9 3.50 375
10 1052 3.5 3.51 417
20 1047 2.5 3.53 458
40 1037 1.5 3.56 534
70 1019 0.81 3.63 636
90 1005 0.60 3.68 695
-29 44 46.68 -25 1082 27.3 3.28 335
-15 1078 15.0 3.29 373
-5 1073 8.6 3.31 411
0 1070 7.0 3.32 431
10 1065 4.8 3.33 466
20 1060 3.4 3.35 501
40 1048 1.9 3.39 568
70 1029 1.0 3.45 659
90 1016 0.73 3.50 712
-36 50 52.70 -35 1097 74.5 3,15 328
-25 1092 34.4 3.17 367
-15 1087 18.6 3.18 404
-5 1082 10.9 3.20 439
0 1079 8.5 3.20 456
10 1074 5.8 3.22 490
20 1067 4.0 3.24 523
40 1056 2.2 3.27 585
70 1037 1.2 3.33 669
90 1023 0.83 3.38 720
All values given in the table above are calculated with mathematical formulas which base on experimental data (can be provided on request). Small deviations from the real values are unavoidable.
Coolex® N: Kinematic viscosity [mm²/s]
Coolex® N: Frost resistance (crystallization point/ solidifying point)[°C]
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