Heidolph Hei-CHILL, Operating Manual, Page: 41 / 92

Attachments
41
Thermal fluids
Each individual thermal fluid covers a recommended temperature range and must be
suitable for the temperature range for your application.
➜ Never use contaminated or degenerated thermal fluid.
The thermal fluid becomes more viscous at the lower limit of the
temperature range and influences the temperature stability, pump
output and cooling output. Especially in water, ice may form that could
destroy the device.
Vapours and odours may develop at the upper limit of the range.
Therefore, only fully utilise the temperature range where required.
Permissible recommended thermal fluids
Heidolph desig-
nation
Chemical
designation
Temperature
range in °C
Viscosity (kin)
in mm²/s
(at 20 °C)
Viscosity (kin)
in mm²/s at
temperature
Thermal fluid Monoethylene
glycol / water
-30 to 90 4 50
to -25 °C
* Safety data sheets for the thermal fluid can be requested at any time if required.
Caution:
Damage to the device, damage to the environment
If water is used as the thermal fluid, incorrect additives could damage
the device and also the environment if the additives escape from the
device.
Do not use the following thermal fluids or additives under any circum -
stances:
▪ Distilled, deionised, fully demineralised water or sea water (due to
their corrosive properties)
▪ Water containing iron (due to rusting)
▪ Untreated river water (due to the formation of algae)
▪ Inorganic salts (due to flocculation)
▪ Chlorine or ammonia as additives (e.g. in cleaning agents and disin -
fectants)
The following water is permissible as a thermal fluid:
▪ Water free of impurities
▪ Water with a pH value between 6.0 and 8.5
▪ Ultra pure water and distilled water after the addition of 0.1 g
sodium carbonate (Na2CO3) per litre of water
The proportion of alkaline earth ions in the water must lie between
0.71 mmol/L and 1.42 mmol/L (corresponds to 4.0 and 8.0 °dH). Hard
water will cause limescale to develop in the device.
In the case of the Heidolph thermal fluid, the water content will fall
after prolonged operation at high temperatures and the mixture will
become flammable (flash point 128 °C).
Use a hydrometer to check the mixing ratio.