TB 9-4931-426-40
NOTE
Follow normal precautions when using thawing rod.
h. Insert triple point of water cell thawing rod (supplied with unit) in well until ice
mantle is free from well. When ice mantle is free, it will remain stationary when cell is
quickly rotated.
NOTE
If ice mantle re-freezes, insert thawing rod for a few seconds to
free it.
i. After ice mantle is free, replace top on triple point of water cell.
j. Verify that pilot light on TI is alternately blinking on and off, and then allow 15 to
20 minutes for stabilization.
CAUTION
Do not allow heavy ice crust to form across surface of water in
glass of triple point of water cell.
k. Establish reference temperature in accordance with (1) through (7) below:
(1) Verify that pilot light on TI is cycling on and off.
(2) Check triple point of water cell for good ice mantle. If necessary, insert thawing
rod into reentrant well until ice mantle is free.
(3) Chill resistance thermometer for 5 minutes and insert into reentrant well of
triple point of water cell.
(4) After at least 3 minutes record super thermometer indication.
(5) Repeat (4) above three times.
(6) Determine average of indications recorded in (4) above.
NOTE
The average value of resistance recorded is for 0.01C and must
be corrected to 0C.
(7) Refer to the calibration table for the resistance thermometer and determine by
interpolation the table resistance ratio value for 0.01C. Divide the resistance obtained in
8. Ice Point Accuracy
a. Performance Check
(1) Fully insert resistance thermometer into TI reentrant well and allow 30
minutes for unit to stabilize.
NOTE
TI should be in operation 1 hour before any readings are taken.
