Calibration - TM-9-6685-202-140068

TM 9-6685-202-14

clockwise until upper and lower housings barely meet.

c. Thermometer and Scale Rod Assemblies. If the

Hold upper housing and crank wheel and then unscrew

thermometer has been removed for replacement, imbed

lower housing by turning it counterclockwise (looking at

the replacement thermometer in the existing clay block

the bottom of lower housing) until sections are

inserts and install the holder and screws.

separated. Tighten split locknut and machine screw.

Reassemble upper and lower housing. Check for proper

NOTE

adjustment of valve seat by raising valve disk

Older

barometers

use

the

approximately 1/16 inch off seat retainer and observing

thermometer rod as a current path to

that seat retainer rests on spacers.

the light bracket; therefore, the rod

must be insulated from ground with

4-15. Calibration

insulator washers. Use the insulator

The barometer shall be calibrated at the intervals

washers

recovered

during

prescribed by TB 750-236.

The procedure for

disassembly.

performing the calibration shall be in accordance with

TB 9-6685-32050.

d. Constant Vacuum Regulator Adjustment. Adjust

control spring in housing by turning crank wheel

4-30