at the 1-psi (6.9-kPa) hydrogen overpressure. Fresh seavater is pumped, 

 counter flow, through milled channels surrounding the copper tubing. 

 The rate is slightly greater than the slurry expulsion rate to provide 

 for water consumed by the reaction. The entering fresh seawater is 

 preheated by the expelled slurry. Tests of the economizer showed it to 

 be approximately 75% effective in recovering heat from the spent elec- 

 trolyte. 



Heat Circulation System 



Heat is distributed to the diver by means of a second fluid (sea- 

 water) that is circulated through a heat distribution garment surround- 

 ing his body. A schematic of the system is shown in Figure 23. The 

 pump circulates water at a rate of 0.6 gal/min (2.27 £/min) through the 

 semi-closed circuit loop. As this fluid passes through the electrolyte- 

 immersed heat exchanger, its temperature is raised to approximately 

 115 F (46 C). A piston-type thermostatic actuator, which is mounted in 

 the temperature control valve (Figure 26), senses the temperature of the 

 water delivered from the heat exchanger. The position of the thermostat 

 is set so that if the temperature exceeds 110 F (43 C), the piston will 

 open a throttling valve that will allow the hot water to escape to the 

 sea. 



An equal volume of cold seawater is automatically taken in through 

 the always-open suction port at the pump. The cold water mixes with the 

 warm water returned from the diver before entering the heat exchanger, 

 and lowers the temperature of the water delivered to the diver. A 

 handle on the valve allows the diver to adjust the set point position of 

 the thermostat. With this handle the diver suit water inlet temperature 

 is adjustable for comfort control. By opening the valve, the diver can 

 bypass some or all of the heated water and circulate cool water through 

 the suit. The high temperature set point can be adjusted to a maximum 

 of 110°F (43°C). 



System Components 



The pumps for circulating the diver suit water and fresh electrolyte 

 are shown in Figure 27. The permanent magnet DC motors are housed in 

 watertight pressure vessels. To avoid the need for shaft seals, mag- 

 netic couplings are used to drive the centrifugal pump impellers. 

 The pumps are activated by an electronic control panel (Figure 27) 

 that also monitors the system. The control panel contains three sets 

 of LEDs* which, when lighted, give the diver the following information: 



Light emitting diodes. 



14 



