by the UCTs. One of the divers felt the probe end of the telescoping rod was slightly heavy and 

 could use a small amount of buoyancy (less than 2 pounds). This addition would make the tool 

 almost neutrally buoyant in the water and easier to handle and operate. 



Two of the divers commented on the need for diver training in the operation of the tool. 

 Neither felt the amount of training required would be excessive, perhaps an hour or so of 

 instruction in its use, restrictions, operating procedure, and search techniques. In addition, many 

 of the operators commented that the audio output turned off at least once when they switched 

 sensitivity settings. 



Controls were judged easy to operate and located properly for a hand-held tool. In the 

 2- to 3-foot visibility, the display could be seen and the individual LEDs were distinguishable. 

 One diver commented that the green color of the display LEDs might be more difficult to see 

 under certain limited visibility conditions than a red display. 



None of the divers felt the need to increase the length of the standoff because of 

 interference from ferromagnetic items of their scuba gear. One diver commented that he was 

 able to swim with the tool as he operated it. 



High/Low Temperature Testing. To verify the operation and performance of the 

 BP&CL at extreme operating and storage temperatures, both high and low temperature tests were 

 performed. Table 8 shows the TEMP thresholds for temperature. Temperature thresholds as 

 listed in the manufacturer's literature on the commercial Ferex are also listed for comparison. 

 Since the modifications to the commercial unit were limited to the housing and the LED operator 

 display, the manufacturer's temperature values apply only to the sensing probe and the processing 

 electronics. 



Table 8. TEMP and Manufacturer Thresholds for Temperature 



Characteristic 



TEMP Thresholds 



Manufacturer 



Operational Water Temperature 



28 to 85 °F 



-22 to 130 "F 



Nonoperational (storage) 

 Temperature 



-20 to 140 °F 



-67 to 158 "F 



To verify the cold operating and cold storage temperature thresholds in the TEMP (28 °F 

 and -20° F, respectively), the BP&CL was tested in the NCEL Polar Laboratory Facility. These 

 tests were performed in air and in a tank filled with fresh water. The temperature in the fresh 

 water tank was regulated by adjustment of the air temperature in the cold chamber. A 

 thermocouple with digital readout was used to monitor the temperature of the water. Air 

 temperature was monitored using the temperature gages provided in the cold chamber. 



To begin the cold tests, the air temperature in the cold chamber was lowered to about 

 -17°F. The BP&CL was then placed in the chamber (going from a temperature of about 63°F 

 to -IT^F) over night while the cold air cooled the water in the tank. In the morning, new 

 batteries were placed in the BP&CL and the tool was turned on and used (in air) to find rebar 

 placed in the cold chamber. The BP&CL was then placed in the tank while the water 



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