ENGINEERING EVALUATION 325 



adjacent to the time-lapse panel, and the voltage analog of the temperature was recorded on the 

 preprinted data forms. 



Humidity sensors were installed in the entry, lab, galley, and berthing areas. The humidity 

 system was similar to the temperature system described above, except for the sensors and a 

 signal converter connected between the sensors and the millivolt-to-current converters. The 

 voltage analog of the humidity was obtained from the meter used in the temperature system. 

 The humidity sensor in the entry area failed to operate after Sealab II was placed on the bot- 

 tom, and no data were obtained from this sensor. 



It would not have been necessary to change the output of the MV/I converters to a voltage, 

 but this was done to permit the output information to be telemetered to shore via the benthic lab. 



EQUIPMENT 



General 



All equipment installed in Sealab II was checked and certified for use in the operational 

 environment. Particular emphasis was placed on the elimination of materials which might in- 

 troduce toxic fumes into the closed atmosphere. All equipment cavities and enclosures were 

 either vented for pressure equalization or were proven to be capable of withstanding 1-1/2 

 times the ambient pressure of the Sealab II atmosphere. Performance characteristics were 

 checked in artificial Sealab environments to ensure required operational performance. All 

 equipment used in Sealab II was essentially "off-the-shelf" hardware. 



Refrigerator- Freezer 



The refrigerator-freezer was a Navy "standard stock" item with refrigerator and freezer 

 capacity of five cubic feet each. The two refrigeration systems were of conventional mechani- 

 cal (Freon) type and were powered by 1/6-hp electrical motors. Insulation consisted of four 

 inches of spun fiber glass. In order to reduce heat losses in the helium-rich atmosphere, two 

 inches of cork insulation was added to the outer surfaces of the cabinet. The standard aneroid 

 temperature-sensing elements, which would not operate properly at hyperbaric pressures, 

 were replaced with mercury sensors. These were well protected to reduce the possibility of 

 rupture and spillage of mercury. 



Cooking Equipment 



The cook top for the galley consisted of four heating units installed in the counter top. 

 Each unit had a heat-control switch. The units were rated at 1250 watts at 220 volts; however, 

 the supply voltage was only 208 volts and the maximum output approximately 1180 watts each. 

 A commercial 1500-watt rotisserie and four-slice standard Navy toaster were also included in 

 the galley equipment. 



Water Heater 



The water heater was a Navy "standard stock" type with a storage capacity of 50 gallons 

 and a recovery rate of 50 gph. Maximum power consumption was rated at 7.6 kw. A 

 temperature-and-pressure-sensitive pressure-relief valve was installed and set for a relief 

 pressure of 100 psig. No special insulation was added to the water heater. 



DISCUSSION AND TEST RESULTS 

 Hull 



General — The hull appeared to be leak free and structurally adequate, and generally per- 

 formed its function well. There was little evidence of corrosion or marine fouling. 



