2
Introduction
The Hart model 9101 zero point dry-well is a precision instrument which main-
tains a constant temperature at 0°C. It can be used to provide a stable zero ref-
erence for thermocouples or for calibrating temperature probes.The 9101 has
three wells so that multiple probes may be calibrated and compared at once.
The 9101 uses solid-state electronics to control the temperature of an aluminum
block. The block temperature is monitored with a high sensitivity thermistor
sensor. The controlling circuit adjusts the current to thermoelectric modules
which cool the block maintaining a stable temperature. Since the current to the
cooling modules is constant DC there is no problem with induced EMF noise in
the user’s probes or thermocouples due to switching transients of the cooling
circuits. Because the temperature control is done with solid-state electronics the
9101 is rugged and stable. The zero point dry-well will not be damaged by
subfreezing temperatures during shipping or storage.
The 9101 is calibrated at the factory for NIST traceable accuracy. It may also
be easily calibrated in the field to the user’s own standard.
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2 Introduction
Figure 1
9101 Zero Point Calibrator