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Physical properties of Thermera
Operating temperature ranges:
Thermera
products can be used within a very extensive operating
temperature range. Freezing point is used as a basis
for product classification.
Standard products: The standard Thermera products are:
-
Thermera AC -
- Thermera R -
The figure in the product name indicates the freezing
point of the product in question, i.e. the recommended
lowest continuous operating temperature of the fluid.
In addition to the above standard products, Thermera
can be delivered, in order to optimise large systems,
with any frost resistance specified by the user, down
to -50°C.
The continuous maximum operating temperature for all
Thermera products is +110°C. In temperatures exceeding
this point, betaine begins to degrade slowly, and in
temperatures exceeding 150°C the degradation is quick.
The degradation products of betaine are not corrosive
or otherwise harmful to people or the environment.
Freezing point
The method used for determination: ASTM D 2386-97 Freezing
point is the temperature below which solid crystals
may build up in a solution. To determine the freezing
point, a solution is cooled down while stirring, until
crystals appear. After the first crystals have built
up, the solution is left to warm up slowly while stirring.
The temperature in which all the crystals have disappeared
is the freezing point of the solution. It is most common
that the freezing point value is given for heat transfer
fluids according to this method. SEE
FREEZING POINT At the freezing point, and at least
4 degrees centigrade below this point, the product is
still completely reliable. This means that Thermera
-20, for instance, can be used in a continuous temperature
of -20°C, and for short periods of time it endures even
about -24°C.
Congealing
point (or solidifying point)
The
method used for determination: ASTM D 1177-65 Congealing
point is another term frequently used for cold endurance.
Congealing point is determined in the same way as freezing
point, but cooling is continued as long as the sample
has undergone so-called thickening, i.e. the viscosity
has increased so much that the solution cannot be pumped
any longer. So congealing point is the temperature in
which the product does not work any longer. For low-concentration
solutions, Thermera products’ congealing point is about
4 degrees lower than the freezing point, and for high-concentration
solutions it is about 10 degrees lower.
Frost
resistance measurements of Thermera products
In
addition to the manufacturer’s own laboratories, the
VTT Technical Research Centre of Finland has also measured
the Thermera products. VTT is an impartial research
organisation of 3,000 employees, which produces a wide
range of technology and research services for both Finnish
and international customers, companies and the public
sector.
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