It is also true that many instruments may be cleaned up and repaired to a minor 

 degree by the field personnel before being returned to the testing stations, thus 

 rendering pre-repair tests ineflfectual. But these conditions can be ironed out. 



6.1.2. Frequency of Calibration 



As mentioned above, most instruments are recalibrated when they are complete- 

 ly inoperative. There should be a properly scheduled system of recalibration of in- 

 struments vi^ithout their having to become inoperative. Recalibration at frequent 

 periods serves to produce more reliable data and more reliable corrective factors 

 for data taken. A three months recalibration period has been generally suggest- 

 ed as a goal to shoot at. Of course, the more frequent, the better, commensurate 

 with reasonable cost, etc. 



6.1.3. Bathythermograph Test Log and Repair History 



In many cases a history of repair is kept of a given Bathythermograph. This 

 has been confined to special instruments used by scientific personnel. 



A complete, up-to-date, test log and repair history for a bathythermograph 

 unit would (1) aid immensely in the evaluation of the data obtained, (2) produce 

 a statistical record of Bathythermograph performance, showing its main manu- 

 facturing weaknesses, and the major causes for damage by the personnel operating 

 them, and (3) establish the optimum time for scheduled recalibration before be- 

 coming inoperative. 



6.1.4. Uniformity Between Testing Stations 



Standardization of testing procedures requires that the various testing sta- 

 tions employ the same techniques for testing, and if at all possible, the same type 

 of testing equipment. In addition, the independent absolute measuring devices 

 should be cross calibrated between stations to insure standard absolute values. 



At present there is some standardization of testing stations attempted through 

 the proper Navy manuals for testing procedures, but in general the actual 

 practices followed are quite varied. It seems quite in order that uniformity be- 

 tween stations be a part of a general program outlining standardization for 

 all test procedures. 



6.1.5. Capacity of Testing Stations 



The older installations hold one or two Bathythermographs for simultaneous 

 test cycles. The newer units on the West Coast can hold up to six units. In view 

 of the large number of Bathythermographs that need frequent recalibration, the 

 testing stations should be designed with the idea of being able to test several 

 units at one time. This is particularly important if the testing cycle is increased in 

 scope to account for the aforementioned features. 



6.1.6. Hysteresis 



It is important that a test pattern to inspect for hysteresis be made in the 

 calibration procedure. A concurrently acting temperature versus depth trace which 

 was then reversed would show any tendency to hysteresis in the instrument. 



6.1.7. Rate of Response 



No test at present computes the rate of response of the Bathythermograph to 

 changes in temperature and depth. Rate of response is particularly important in 



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