turn, ball valve has been placed in each line bypassing the 

 needle valves. Use of these allows more rapid transfer 

 of water and has reduced the total time needed between 

 calibration points. 



AIR CONDITIONING 



An air conditioning system was installed in the 

 calibration room to maintain the air temperature within 

 ±2°C. Previously, considerable changes in ambient temper- 

 ature occurred throughout the day due to solar heating of the 

 south wall. The atmospheric temperature stabilization in 

 the room has now made control of the bath temperature to 

 ±0, 002°C possible throughout an operation. 



ARRANGEMENT OF CONTROLS 



The controls for the calibration tank, the thermal 

 system, temperature controller, and temperature standard 

 are within easy reach of the operator (fig. 8). A large 

 space immediately in front of the tank allows him to have 

 easy access to the water even if he is working with bulky 

 transducers and cumbersome bundles of cables. There is 

 adequate room for recorders and resistance bridges used 

 in the calibration of the instruments. 



.^TEMPERATURE 

 /RECORDER-MONITOR 



CONTROL PANEL 



^WITCHE" 



TEMPERATURE 

 • . •_fi/CONTROLLER 



MUELLER BRIDGE 



TEMPERATURE STANDARD) 



[TABLES FOR CONVERTING 

 MUELLER BRIDGE 

 RESISTANCE READINGS 

 TO DEGREES CENTIGRADE 



Figure 8. Access fo all controls by operator. 



17 



