About The Graph; Stirring - Fluke 7102 User Manual

About the Graph

The fluid graph illustrates some of the important qualities of the fluids shown.
Temperature Range: The temperature scale in the graph is in degrees Celsius. The fluids' general
range of application is indicated by the shaded bands. Qualities that include pour point, freeze point,
important viscosity points, flash point, boiling point, and others may be shown.
Freezing Point: The freezing point of a fluid is an obvious limitation to stirring. As the fluid approaches
the freezing point, high viscosity can also limit performance.
Pour Point: This represents a handling limit for the fluid.
Viscosity: Points shown are at 50 centistokes and 10 centistokes viscosity. When viscosity is greater
than 50 centistokes stirring is poor and the fluid is unsatisfactory for bath applications. Optimum stirring
generally occurs at 10 centistokes and below.
Fume Point: Use a fume hood. This point is subjective in nature and is impacted by individual
tolerance to different fumes and smells, how well the bath is covered, the surface area of the fluid in the
bath, the size and ventilation of the facility where the bath is located, and other conditions. It is
assumed that the bath is well covered at this point. This is subject to company policy.
Flash Point: The point at which ignition can occur. The point shown can be either the open or closed
cup flash point. Refer to the flash point discussion in
Boiling Point: At or near the boiling point of the fluid, the temperature stability is difficult to maintain.
Fuming or evaporation is excessive. Large amounts of heater power may be required because of the
heat of vaporization.
Decomposition: The temperature can reach a point at which decomposition of the fluid begins.
Further increasing the temperature can accelerate decomposition to the point of danger or
impracticality.

Stirring

Stirring of the bath fluid is important for stable temperature control. The fluid must mix well for good
temperature uniformity and fast controller response. The stirrer is adjusted for optimum performance.
Table 4 shows nominal stirrer motor settings for several fluids.
If the stirrer does not function properly, the instrument oscillates and will not meet published
specifications.
If the bath is used with the probe basket removed, change the stir motor settings until a small
vortex is seen in the liquid.
Do not mix water and oil when you exceed temperatures of 90 °C.
Bath Fluid.
Note
W
Warning
Micro-Bath
Stirring
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