TB 9-4931-428-40
9. Temperature Calibration
a. Performance Check
NOTE
This procedure is to be used for initial calibration of all TI's.
Thereafter the TI will be checked at ZERO point only.
Changes in correction at ZERO point will be applied to all
corrections. That is, if the ZERO point correction increases,
then the increase will be added to all corrections. If the ZERO
point decreases, then the decrease will be subtracted from all
corrections. If the shift in ZERO point exceeds rejection
tolerance specified in table 4, the TI will be replaced. TI's
which do not have ZERO points will be tested at some other
point. Testing at some temperature other than ZERO point
requires a controlled temperature calibration bath and a
temperature standard.
NOTE
Perform (1) through (14) below for initial calibration only. For
subsequent calibrations perform (15) below only.
NOTE
Ensure proper coefficients are loaded into the super
thermometer for the resistance thermometer being used.
(1) Ensure resistance thermometer is connected to the correct channel of the
super thermometer.
(2) Prepare temperature bath No 1 and adjust for 0C indication.
(3) Insert resistance thermometer into temperature bath No. 1.
(4) Record super thermometer indication after at least 3 minutes.
(5) Repeat (4) above three times.
(6) Determine average of indications recorded in (4) above.
(7) When calibrating thermometer set 7910479, select TI model 62C as first item to
be calibrated.
(8) Adjust temperature bath No. 1 to -30 C.
(9) Lower resistance thermometer into temperature bath along with TI selected in
(7) above.
(10) Allow sufficient time for TI and resistance thermometer to stabilize, and record
TI temperature and temperature of resistance thermometer.
(11) Compare TI temperature with temperature of resistance thermometer recorded
in (10) above. Record deviation of TI from resistance thermometer.
(12) Repeat (10) above three times at 5 minute intervals.
