milled-flat cast aluminum top. All functions are settable from the digital front panel and display.
These units when received display temperature in
º
C. They may be switched to read in
º
F. See
page 6.
HEATER
Either the plate surface temperature or the actual sample temperature may be set. A sensor in the
plate is used to monitor surface temperature, or, alternately, a 100-ohm, 3-wire, platinum RTD
temperature probe may be connected to the rear of the unit and inserted into the sample to
measure sample temperature. When a temperature is set, power is applied to the heater to
precisely control the temperature at the plate surface or at the sample, as directed by the user.
An optional ramp value may be entered into the unit which causes the temperature to approach
the target value at a controlled rate of temperature change. This can be either an increase or
decrease in temperature. Ramp temperature is always displayed in degrees centigrade.
TIMER
All models come with a count down timer that is settable and displays in hours, minutes and
seconds. The timer can be set to 99:59:59 hours. When the timer is set it starts to count down to
zero. At zero the timer will sound an audible alarm that will ring five times. In addition to the
timer, the unit has an AUTO-OFF function. When the AUTO-OFF function is activated the
heater and stirrer will turn off at the end of any count down timer setting.
ALARMS
In addition to the audible alarm associated with the count down timer, all models have an
over
temperature alarm
that activates at 455
Ε
C on ceramic topped units and 405
º
C on aluminum
topped units. If, for any reason, the plate surface temperature runs away and exceeds either
value, the units will turn on the over temperature alarm LED, sound an audible alarm, and shut
the heater off. If or when the heater plate surface cools to below 450
º
C for ceramic tops or
400
º
C for aluminum tops, the heater will turn on again, and the alarm LED and audible alarm
will turn off.
NOTE: Failing to place the temperature probe in the solution and then setting
a probe temperature will cause the heater to heat to over 455
Ε
C and set off the OVER
TEMPERATURE ALARM. Also, the OVER TEMPERATURE ALARM may come on if a
very large sample is placed on the unit and a probe temperature is set. This setting can
cause the heater surface to go over 455
Ε
C to achieve the probe temperature set to heat the
large sample.
STIRRERS
All stirrers are a motor driven magnet which revolves directly under the heater plate. It is
normal to stir a solution while heating. A stir bar is used in the solution and couples with the
motor driven magnet and stirs the solution.
5
VII. FRONT AND REAR PANEL CONTROLS
FRONT PANEL
