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10.10 Temperature verication
The temperature calibration curve is stored in the sensor
memory and cannot be modied. The calibration is set once at
the factory and do not require subsequent adjustment.
Nevertheless it is recommended to check the temperature
accuracy once a year. A one point check is enough to qualify
the sensor.
10.10.1 Equipment required
• A Dewar ask or any vacuum ask, approximately 8 cm in
diameter and 36 cm deep.
• Ice, preferably made from distilled water.
• Water, preferably distilled and precooled.
10.10.2 Preparing the Ice Point bath
(1) Shave or crush the ice into small pieces, avoiding direct
contact with the hands or any unclean object. The pieces
shall be no more then 5 mm.
(2) Fill the Dewar ask with the crushed ice and add sufcient
water to form a slush, just lling the voids between ice
particles but not enough to oat the ice.
(3) Insert the sensor, packing the ice gently about it.
(4) Let it stand for half an hour to permit the sensor
temperature, the ice particles and the water to equilibrate.
(5) As the ice melts it will be necessary to drain off some water
and add more crushed ice. Gently stir the ice with the sensor
periodically to assist equilibration.
IMPORTANT NOTE: Attention to detail during the preparation
of the Ice Point bath is critical to the accuracy and quality of the
offset verication.
10.10.3 Checking the UTImeter
(6) After 30 minutes have elapsed, gently stir the bath with
the sensor again to ensure complete equilibration of
temperature.
(7) Switch on the UTImeter.
(8) Observe the reading. It should be ±0.10 °C (±0.20 °F)
The temperature must be stable, i.e. within ±0.04 °C
(±0.07 °F).
(9) If it is not OK, refer to section 11 “Trouble shooting”.
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