CALIBRATION OF REVERSING THERMOMETERS 



SELECTION AND PREPARATION 



Reversing thermometers are calibrated in groups 

 of 24 with a reliable laboratory standard included in No. 1 

 position of the rack. All thermometers are first carefully 

 inspected and reversed at room temperature to ensure that 

 they will operate properly after insertion in the tank. Any 

 which may require a slight tap to break the mercury 

 column are positioned on either side of No. 1 where they 

 can be reached easily after reversal. Identification numbers, 

 storage numbers in the exercising rack (fig. 11), range, 

 interval, original and latest V^, K, Q, and owner, are listed 

 on individual calibration sheets (fig. 12). The serial 

 number on each thermometer is verified as it is placed in 

 the tank rack. 



The tank temperature is reduced to the lowest 

 scale reading of the main stems prior to loading the ther- 

 mometers in the rack. During the loading process the tank 

 walls and insulation have time to stabilize (approximately 



ti i! S ! . . 



REVERSING RACK 



THERMOMETERS 



Figure IT. Exercising and storage rack for reversing thermometers. 



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