7341
Users Guide
8-6
significant. The vapors may be dangerous and a fume hood or adequate ventilation
system should be used. As with most oils, mineral oil expands as temperature increases.
Be careful not to fill the bath too full to avoid overflows when heated (see Fluid
Expansion Reservoir in Chapter 7). 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 Oil
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.
Silicone oils are fairly safe and non-toxic, but can be fairly expensive.
Fluid Characteristics Charts
Caution
Due to the unique properties of silicone oils and their ability to
migrate and creep through seals, adequate ventilation must be
used to prevent oil vapors from creating an oily, dirty
environment. Oily, dirty environments reduce the lifetime of the
instruments electrical components.
Table 8-1 and Figure 8-1 have been created to provide help in selecting a heat exchange
fluid media for your constant temperature bath. These charts provide both a visual and
numerical representation of most of the physical qualities important in making a selection.
The list is not all inclusive. There may be other useful fluids not shown in this listing.
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.
Limitations and Disclaimer
The information given in this manual regarding fluids is intended only to be used as a
general guide in choosing a fluid. Though every effort has been made to provide correct
information we cannot guarantee accuracy of data or assure suitability of a fluid for a
particular application. Specifications may change and sources sometimes offer differing
information. Fluke cannot be liable for any personal injury or damage to equipment,
product or facilities resulting from the use of these fluids. The user of the bath is
responsible for collecting correct information, exercising proper judgment, and insuring
safe operation. Operating near the limits of certain properties such as the flash point or
viscosity can compromise safety or performance. Your company’s safety policies
regarding flash points, toxicity, and such issues must be considered. You are responsible
for reading the MSDS (material safety data sheets) and acting accordingly.
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