(1) The instructions outlined in this section are preparatory to the calibration
process. Personnel should become familiar with the entire procedure before
(2) Items of equipment used in this procedure are referenced within the text by
common name and item identification number as listed in tables 2 and 3. For the
identification of equipment referenced by item numbers prefixed with A, see table
2, and for prefix B, see table 3.
f. Equipment Setup
NOTE: Avoid unnecessary drafts on standard thermometer and TI during calibration.
(1) Remove TI from protective case.
(3) (This step is for liquid-in-glass thermometers only.) Hold TI in vertical
position. If bulb and column are not free from gas bubbles and stem is not free
from globules of liquid, perform following steps if applicable.
(a) 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
or against palm of hand. Bubbles should rise to surface and disperse.
(b) Eliminate gas bubbles from stem of TI by slowly and carefully heating
bulb until bubbles are joined. Carefully tap TI against pad of paper or
against palm of hand.
To avoid damage to TI, exercise extreme care when applying heat.
Damage may result if thermometer or or bulb is overheated.
(c) 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.
g. Calibration Process
NOTE: Unless otherwise specified, verify the results of each test and take corrective
action whenever the test requirement is not met before continuing with the calibration.
NOTE: The range of the standard thermometer overlap. Select the standard thermometer
with the best accuracy for the specific temperature check to be made.
h. Ambient Temperature
(1) Performance Check
(a) Place TI and appropriate standard thermometer (A1 or A2) side by side
in vertical position, using support stand (B3). Allow approximately 15
minutes for TI to stabilize.
(b) Compare indication of TI and standard thermometer and record the
NOTE: The temperature conversion formulas below may be used:
F = (C x 9/5 +32)
C = 5/9 x (F-32)
(c) Repeat (b) above twice.
(d) Average the three indications recorded in (b) above. The average will
not exceed a value four times greater than the accuracy of the standard