Over-Temperature Detector; Thermometer Holes - Welch Allyn 9600 Operation Manual

Welch Allyn 9600 Calibration Tester

OVER-TEMPERATURE DETECTOR

In addition to the READY Indicator, the 9600 Calibration Tester contains an
"Over-Temperature Detector." This is a fail-safe feature that protects the
unit against over-temperature conditions, in the unlikely event that a failure
should occur in the temperature-control circuitry. The over temperature
control circuit overrides the normal control circuit, and holds the tempera-
ture slightly above the set point.
If a failure were to occur in the circuitry and it caused the unit to keep
heating indefinitely, the Over-Temperature Detector would activate as soon
as the temperature rose a few tenths of a degree above the set point. If this
were to happen, the READY indicator would not illuminate, thereby alerting
the user that the unit should not be used.

THERMOMETER HOLES

The internal "blackbody" of the 9600 Calibration Tester acts as a heat
reservoir for the thermistor probe and as a heat radiator for the infrared-
sensing aural thermometer.
The large hole under the flap in the top of the Main Unit is for Model 9000
infrared (IR) Aural thermometers and the small hole is for thermistor-based
thermometers. For proper positioning of the thermometers in these holes,
see the following section, "Using the 9600 System."
The surface texture inside the large hole must be flat (dull) and dry for
proper IR readings. This hole should be black; you should only be able to
see its surface under bright light. The small hole, which is not painted black,
must be kept clean and dry.
The coating in this part of the unit is fragile, so please follow the cleaning
instructions carefully. The surface of the unit should not be touched, nor
should any foreign objects be inserted into the unit. It also is important to
avoid spilling liquids onto the unit, even though it has a dust cover. If liquid
or other contaminants are allowed to enter the unit, proper calibration
cannot be assured.
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