TB 9-4931-426-40
Table 2. Minimum Specifications of Equipment Required
Manufacturer and model
Common name
Minimum use specifications
(part number)
Range: -30C to +260C
Rosemount Aerospace, Model 162C
Accuracy: 0.003C
THERMOMETER
or 162CE
SUPER
Range: -38C to +250C
Hart Scientific, Model 1590
THERMOMETER
Accuracy: 0.003C
TRIPLE POINT OF WATER Set point: 0.0100C
Invensys Systems, Model 5901A or
Accuracy: 0.0005C
CELL
5901B
CALIBRATION PROCESS
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
name as listed in tables 2.
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 this TI.
d. Unless otherwise specified, all controls and control settings refer to the TI.
7. Equipment Setup
a. Ensure that reentrant well of TI is filled with mineral oil.
b. Turn TI ON-OFF power switch to ON, and allow 45 minutes for unit to cycle
(blinking of pilot light).
c. Remove triple point of water cell rubber well insert, drain water residue, and pre-
cool complete cell assembly by refrigeration for at least 12 hours.
NOTE
Make sure that pre-cooling does not freeze water in glass cell.
d. Dry triple point of water cell carefully, particularly thermometer well, and replace in
insulating jacket.
e. Place triple point of water cell in vertical position and fill well with pulverized dry
ice (fine snow to 1/16 inch particles), using plastic funnel. Replenish as necessary until ice
mantle forms.
f. Allow ice mantle to form and completely envelop well; mantle must not touch outer
glass wall. When satisfactory mantle is formed, pour out dry ice.
g. Insert small piece of rubber into well to protect glass bottom.
