TB 9-4931-428-40
6. Preliminary Instructions
a. The instructions outlined in paragraphs 6 and 7 are preparatory to the calibration
process. Personnel should become familiar with the entire bulletin before beginning the
calibration.
b. Items of equipment used in this procedure are referenced within the text by common
c. Unless otherwise specified, verify the result of each test and, whenever the test
requirement is not met, take corrective action before continuing with the calibration.
Adjustments required to calibrate the TI are included in this procedure. Additional
maintenance information is contained in the manufacturer's manual for the TI.
a. Remove TI from protective case.
b. Inspect TI bulb and stem for foreign matter and evidence of deterioration.
c. Hold TI in vertical position and verify that bulb and column are free from gas
bubbles and stem is free from globules of liquid. If not, perform (1), (2), or (3) below
as applicable.
(1) Eliminate gas bubbles in TI bulb by cooling with dry ice or equivalent coolant
until liquid is drawn into bulb. Tap TI gently against pad of paper. Bubbles should rise to
surface and disperse. Hold TI upright while allowing it to return to room temperature.
(2) Eliminate gas bubbles from stem of TI with expansion chambers by slowly and
carefully heating bulb until bubbles are joined. Carefully tap TI against pad of paper or
against palm of hand.
CAUTION
To avoid damage to TI, exercise extreme care when applying
heat. Do not heat with open flame.
(3) Eliminate globules of liquid inside TI stem by carefully and slowly heating TI
bulb until liquid column merges with globules.
NOTE
If globules tend to unite and reappear after bulb cools,
obstructions or oxidation of mercury may be present, and TI
must be rejected.
d. Prepare temperature standard for proper ice mantle formation.