10. The major problem yet to be resolved in the development of a free- 

 swimming diver-carried dual-plate heater is the venting of hydrogen 

 produced by the reaction. The vent system must be operable in virtually 

 any orientation, while preventing excessive electrolyte leakage to sea. 

 Operation of the vent system is further complicated by the clogging 

 nature of the Mg(0H)„ reaction by-products. 



11. The alloyed magnesium-iron powders offer a viable solution to some 

 of the undesirable characteristics of the dual-plate cells, including: 



(a) Higher specific output than the dual-plate cell 



(b) Constant or controlled power output 



(c) Attitude insensitive to venting of H2 



(d) Easily modularized to suit mission requirements 



RECOMMENDATIONS 



1. A plate-type (dual or iron-plated) magnesium-iron heater for use in 

 limited orientation situations, such as mounted on a PTC, SDV or submer- 

 sible, should be built and tested. This heater could also be used as a 

 standby emergency heater for the same vehicles. 



2. Additional test and evaluation of magnesium-iron powdered alloys, 

 including other cathodic materials, should be conducted. Based on the 

 results of these tests, a portable diver-carried heater with constant or 

 variable power output should be designed, fabricated, and tested. 



REFERENCES 



1. Naval Medical Research Institute. Report no. 2: Theoretical 

 thermal requirements for the Mark II diving system, by J. F. Tauber, J. 

 S. P. Rawlins, and K. R. Bondi. Bethesda, Md., 1969. (AD 694013) 



2. Naval Coastal Systems Laboratory. Informal Status Report: Thermal 

 comparison of various diver suit materials, by R. K. Johnson. Panama 

 City, Fla., Mar. 1973. 



3. Navy Experimental Diving Unit. Report no. NEDU-RR-3-51: Test of 

 electrically heated clothing, by T. N. Blockwick. Washington, D. C, 

 Feb. 1951. (AD 731013) 



4. Naval Civil Engineering Laboratory. Technical Note N-1015: Marine 

 Corps diver's backpack battery assembly, by D. Taylor and J. J. Bayles. 

 Port Hueneme, Calif., Jan. 1969. 



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