282 



WET SUITS 



Table 36 



THERMAL CONDUCTIVITY OF VARIOUS MATERIALS [10] 



(Range of Typical Values Near Room Temperature) 



♦ Somewhat lower for sea water depending on pressure, 

 temperature, and salinity. 



Table 37 



BREAK CHARACTERISTICS OF MICROBALLOON/ 



PVC PLASTISOL SAMPLES 



Self- Contained Power Source 



The choice of heat-release materials (resistance wires, carbon yarn, liquids, etc.) would 

 have to be made after selection of the portable power pack for use by the free- swimming aqua- 

 naut. Overall power efficiency was the principal criterion, because of the rather high heat 

 level required and the long exposure period (three hours). 



Radio-isotopes, thermochemical reactions, fuel cells, and thermoelectric heating were 

 ruled out on the basis of nonavailability of off-the-shelf components which could be integrated 

 into a suit system. Secondary cells were considered because of their availability and the need 

 for only minor modifications to adapt them for the application. 



A simple formula was derived to determine the size and apparent weight in water of sec- 

 ondary batteries providing one kilowatt-hour of stored energy. The apparent weight is: 



W. 



(W, 



,) 



where 



Wj, is the dry weight of the battery, lb 



Vb is the volume of the battery, in.^ 



P^ is the weight density of sea water, 0.037 lb/in. ^ [11] 



