Stirring; Power; Heater - Fluke 7012 User Manual

Fume Point: The point at which a fume hood should be used. This point is
very 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
others. We assume the bath is well covered at this point. This is also subject to
company policy.
Flash Point: The point at which ignition may occur. See flash point discussion
in Section 8.1.8. The point shown may be either the open or closed cup flash
point.
Boiling Point: At the boiling point of the fluid the temperature stability is diffi-
cult to maintain. Fuming is excessive. Excessive amounts of heater power may
be required because of the heat of vaporization.
Decomposition: All high temperature fluids may be reach a temperature point
at which decomposition of some form will begin. While it always begins slowly
at some lower temperature, the rate can increase to the point of danger or im-
practicality at a higher temperature.
8.2

Stirring

Stirring of the bath fluid is very important for stable temperature control. The
fluid must be mixed well for good temperature uniformity and fast controller
response. The stirrer is precisely adjusted for optimum performance.
8.3

Power

Power to the bath is provided by an AC mains supply. Refer to Section 3.1,
Specifications, for power requirement details. Power to the bath passes through
a filter to prevent switching spikes from being transmitted to other equipment.
Refer to and read the WARNING at the front of this manual concerning brown-
out and over voltage protection.
To turn on the bath switch the control panel power switch to the ON position.
The stir motor will turn on, the LED display will begin to show the bath tem-
perature, and the heater will turn on or off until the bath temperature reaches
the programmed set-point.
When powered on the control panel display briefly shows a four digit number.
This number indicates the number of times power has been applied to the bath.
Also briefly displayed is data which indicates the controller hardware configu-
ration. This data is used in some circumstances for diagnostic purposes.
8.4

Heater

The power to the bath heater is precisely controlled by the temperature control-
ler to maintain a constant bath temperature. Power is controlled by periodically
switching the heater on for a certain amount of time using a solid-state relay.
8 General Operation
Stirring
33