DRUCK & TEMPERATUR Leitenberger GmbH •
Bahnhofstr. 33 • D-72138 Kirchentellinsfurt • GERMANY
Tel. +49 (0) 7121-90920-0 • Fax +49 (0) 7121-90920-99 • [email protected] •
• www.druck-temperatur.de
www.LR-Cal.net
MANUAL
Portable Temperature Calibraon Bath
FLUID 100 and FLUID 100-N
14
3.1.2 Viscosity
Viscosity is the property of fluids that indicates it‘s resistance to mixing and it depends on the type
of fluid and temperature.
The more viscous the fluid, the more difficult the mixing of the fluid and consequently the
distribuon of a uniform temperature inside the bath.
Liquids with a viscosity higher than 20 censtokes (cts) do not allow a good performance of the
bath, therefore they should be avoided in the
and
. Oil
FLUID 100
FLUID 100-N
LR-
LR-
Cal
Cal
viscosity is established at room temperature.
The value for water (at 20°C) is
1 cst.
Viscosity at room temperature
silicone oil 47V5
5 cst
silicone oil 47V10
10 cst
water-glycol-mix 50%
5 cst
Remember that viscosity, especially in oils, varies considerably when the temperature changes:
this is the reason that characterises the use of oil in a well-defined field: normally the oil becomes
more viscous when the temperature drops, creang problems in mixing and uniform distribuon
of the temperature.
3.1.3 Thermal expansion
Thermal expansion indicates how liquid volume changes with variaon of the temperature. It is an
important factor especially regarding oils, which increase in volume with increase of temperature.
Read the filling instrucons and do not fill over the values indicated because thermal expansion
could cause the liquid to escape from the bath.
Silicone oils increase by about 10% with respect to their inial volume with a temperature increase
of 100°C.
3.1.4 Life span
The life span that you can expect depends on many condions: evaporaon, chemical
deterioraon, gelling, etc.
The life span of an oil becomes shorter becauer the higher the temperature the greater oxidaon
of the oil in contact with air.
To increase the life span:
• Use the most suitable oil at high temperature for the shortest me possible
• Place the appropriate cover with holes on the bath to allow passage of the probes, in order to
limit contact between the hot oil and air.
For example: connous use at 125°C, in open bath condions, of 47V5 silicone oil cause
deterioraon in a few tens of hours; with the deterioraon of its condions the viscosity increases
considerably; at temperature below zero the 47V5 silicone oil becomes doughy and mixing in the
bath is impossible.
3.1.5 Bath filling
Fill the temperature calibrator with the suitable fluid depending on the field of calibraon. The
liquid we recommend is 47V5 silicone oil (resp. 47V10). Fill the bath with about 43-43 cl of oil. Do
not exceed the recommended quanty, as the thermal expansion at high temperatures could
cause the liquid to escape from the upper opening.
