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7012 Calibration Bath
User's Guide
8.1.10.4
8.1.10.5
8.1.11
8.1.11.1
30
low freeze point. Methanol is very toxic so care must be taken when using and
disposing of this fluid.
Mineral Oil
Mineral oil or paraffin oil is often used at moderate temperatures above the
range of water. Mineral oil is relatively inexpensive. At lower temperatures
mineral oil is quite viscous and control may be poor. At higher temperatures
vapor emission becomes significant. The vapors may be dangerous and a fume
hood should be used. As with most oils mineral oil will expand as temperature
increases so be careful not to fill the bath too full that it overflows when heated.
The viscosity and thermal characteristics of mineral oil is poorer than water so
temperature stability will not be as good. Mineral oil has very low electrical
conductivity. Use caution with mineral oil since it is flammable and may also
cause serious injury if inhaled or ingested.
Silicone Oils
Silicone oils are available which offer a much wider operating temperature
range than mineral oil. Like most oils, silicone oils have temperature control
characteristics which are somewhat poorer than water. The viscosity changes
significantly with temperature and thermal expansion also occurs. These oils
have very high electrical resistivity. Silicon oils are fairly safe. These oils are
relatively expensive.
Fluid Characteristics Charts
Table 2
and
Figure 6
have been created to provide help in selecting a heat ex-
change fluid media for your constant temperature bath. The charts provide both
a visual and numerical representation of most of the physical qualities impor-
tant in making a selection. The list is not all inclusive, many usable fluids may
not have been shown in this listing.
Limitations and Disclaimer
Every effort has gone into making these charts accurate, however, the data here
does not imply any guarantee of fitness of use for a particular application.
Working near the limits of a property such as the flash point or viscosity limit
can compromise safety or serviceability. Sources of information sometimes
vary for particular properties. Your company's safety policies as well as per-
sonal judgment regarding flash points, toxicity, etc. must also be considered.
You are responsible for reading the Material Safety Data Sheets and making a
judgment here. Cost may require some compromises as well. Hart Scientific
cannot be liable for the suitability of application or for any personal injury,
damage to equipment, product or facilities in using these fluids.
The charts include information on a variety of fluids which are often used as
heat transfer fluid in baths. Because of the temperature range some fluids may
not be useful with your bath.
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