performed and can be recognized by progres- 

 sive erratic operation. Since reversing ther- 

 mometers which have given satisfactory serv- 

 ice for iy2 years or longer rarely develop this 

 condition, the instruments which develop aging 

 symptoms within this period of time, probably, 

 had one or more of the following faults when 

 they were fabricated : 



Marginal bore diameters at critical places; 



Poorly shaped appendixes; 



Glass stresses from inadequately controlled 

 annealing processes. 



G-4 Equipment and Materials for Manipu- 

 lating Malfunctions. — Equipment and mate- 

 rials for alternately freezing and heating the 

 mercury in the reversing thermometer are re- 

 quired for manipulating malfunctions. In some 

 instances it is desirable also to cool and heat 

 different areas of the instrument simultane- 

 ously. The following items should be available 

 for manipulating malfunctions : 



Ice, dry ice, and/or CO2 gas ; 



Alcohol ; 



A hand hot-air gun (approximately 1,000 

 watts) ; 



A small rubber headed hammer ; 



Several 2,000 ml. beakers, preferably metal; 



A metal pan (approximately 15 inches long, 

 8 inches wide, and 6 inches deep). 



G-5 Detecting the Malfunction in a Revers- 

 ing Thermometer. — In the field, certain mal- 

 functions are obvious and easily detected while 

 others are erratic and can be discovered only 

 by comparing a suspect thermometer with prop- 

 erly functioning instruments. The most com- 

 mon and also the most obvious malfunction is 

 the FTD (fails to drain when righted) type. 

 It is simple to detect and verify, and it is the 

 only malfunction that field personnel should 

 attempt to manipulate aboard ship. All other 

 suspected or observed malfunctions should be 

 verified by the following procedures since even 

 the best reversing thermometer fails to f imction 

 properly on occasion : 



If the malfunctioning or suspect instrument 

 is a protected thermometer, move it to a Nansen 

 bottle equipped with a triple frame containing 

 two properly functioning instruments and 

 check its performance for several casts. 



If the malfunctioning or suspect instrument 

 is an unprotected thermometer, move it to a 

 Nansen bottle equipped with a quadruple 

 frame containing two protected thermometers 

 and an unprotected thermometer which are 

 functioning properly, and check its perform- 

 ance for several casts. If a quadruple frame is 

 not available, move the unprotected thennom- 

 eter to the surface Nansen bottle where its tem- 

 perature should agreed with the protected 

 thermometers. If the malfunction persists, dis- 



G-2 



continue using the thermometer on the opera- 

 tion, tag the instrument with a band of masking 

 tape carrying the type malfunction abbrevia- 

 tion, make an entry on the Reversing Thermom- 

 eter Calibration and History Record (ch. F, 

 fig. F-1), and store the malfunctioning ther- 

 mometer in the carrying case. 



G-6 Manipulating the FTD Type Malfunc- 

 tion Aboard Ship. — In most instances wlien the 

 mercury in a reversing thermometer persist- 

 ently fails to drain back into the reservoir un- 

 less the instrument is tapped, the shape given 

 the throat and bulb of the thermometer during 

 fabrication is responsible. This is the situation 

 in many cases of "failure to drain" and while 

 the inaction is rightly termed, "improper mer- 

 cury behavior," it is not considered a malfunc- 

 tion because the fault can be corrected simply 

 by tapping the Nansen bottle gently. 



On the other hand, sometimes the mercury in 

 a thermometer deteriorates slightly and the im- 

 purities subsequently formed accumulate in the 

 bulb end when the thermometer is left in an 

 inverted position for an unusually long period 

 of time. These thermometers will drain errati- 

 cally at times when righted until the mercury 

 has been thoroughly mixed as a result of the 

 thermometer being exercised. Inexperienced at- 

 tempts to manipulate this simple malfunction 

 results in many good thermometers becoming 

 jDermanently malfunctional from being pounded 

 or jarred on the bulb end to relieve the condi- 

 tion. In most cases the desired manipulation is 

 not successfully achieved and fractures are 

 often created in other critical places of the 

 thermometer. 



When drainage cannot be stimulated by 

 gently tapping the Nansen bottle, the thermom- 

 eter should be considered malfunctional and 

 the following steps should be performed : 



Step 1. Remove the instrument from the Nan- 

 sen bottle thermometer frame and try to stim- 

 ulate drainage by the wrist-flip action (fig. G-1) 

 or by a very light tapping on the bulb end of 

 the thermometer. If this causes the bulb to drain 

 go to step 4. 



Step 2. If this does not stimulate drainage, 

 immerse the entire thermometer in a water bath 

 at 75° C. for about 10 minutes. This warms the 

 mercury enough so that slight tapping will 

 often free it in the bulb and cause it to drain 

 into the reservoir. If it drains go to step 4. 

 Never place thermometer in a horizontal posi- 

 tion. Tilt slightly. 



Step 3. In cases where step 2 is not successful, 

 immerse tlie reservoir end of the thermometer 

 in an ice-, or dry ice-, alcohol solution and draw 

 most of the mercury down into the reservoir 

 (CO2 gas can be used). At the same time, heat 

 the bulb end of the thermometer with a hot-air 

 gun (fig. G-2) while the mercury in the reser- 



