Flash Point:
The point at which ignition may occur. The point shown may be
either the open or closed cup flash point. Refer to the flash point discussion in
Section 8.1.8, Safety.
Boiling Point:
At or near the boiling point of the fluid, the temperature stabil-
ity 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 may reach a point at which decomposition of
the fluid begins. Further increasing the temperature may accelerate decomposi-
tion to the point of danger or impracticality. Silicone oils can oxidize causing
the fluid to thicken. Replace fluids at the first sign of increasing viscosity.
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 a grounded AC mains supply. Refer to Section
3.1, Specifications, for power details. Power to the bath passes through a filter
to prevent switching spikes from being transmitted to other equipment.
To turn on the bath, switch the control panel power switch to the ON (I) posi-
tion. The stirring motor turns on, the LED display begins to show the bath tem-
perature, and the heater turns 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.
The front panel red/green control indicator shows the state of the heater. The
control indicator glows red when the heater is on and glows green when the
heater is off. The indicator pulses constantly when the bath is maintaining a sta-
ble temperature.
6331 Calibration Bath
User’s Guide
34
