matic and manual monitoring of atmospheric 
contaminents must be considered. For most com- 
pounds, commercial detection units are available; 
however, each has certain shortcomings. Manual 
sniffers are extremely reliable and should be used 
for backup and checking automatic units. Many 
types of hardware have been employed in existing 
diving systems and submersibles. 
Components and materials must be screened as 
soon as preliminary designs are begun. Paints and 
adhesives must be selected with care, for many 
evolve toxic gases during deterioration. Consum- 
ables brought into the structure must be con- 
trolled, including lubricating oils, halogenated 
hydrocarbon solvents, and aerosol packaged prod- 
ucts. When passed through the catalytic burner, 
many create such chemical derivatives as hydro- 
chloric and hydrofluoric acid vapors, even more 
dangerous than the original products. Similarly 
corrosion, fire, and explosion hazards must be 
eliminated through constant surveillance. 
Emergency breathing stations should be in- 
stalled in numbers to support the occupants while 
rescuing them from the station or raising it to the 
surface. Such a system would have to be closed- 
circuit to preclude excessive internal pressure 
build-up within the vehicle or station, unless 
anticipated rescue time is very short. 
Additionally, backpack breathing sets may be 
furnished for use in contaminated areas. These 
must be untethered to allow wearer to pass 
through a lock. When personnel return from a 
contaminated space, some of that atmosphere will 
be brought into the general living compartments; 
provision must be made to control such contami- 
nation. 
b. Climate Control The function of an air condi- 
tioning system is to remove heat and humidity 
from air used as a heat sink by personnel, 
electronic equipment, and various auxiliary equip- 
ment. Within certain limits, control of compart- 
ment temperature and relative humidity is neces- 
sary for personnel comfort and proper operation 
of internal equipment. 
Design of the air conditioning system will be 
influenced by: 
—Outside water temperature. 
—The need to minimize the number and size of 
pressure hull penetrations. 
VI-74 
Three methods of air conditioning are available: 
—Vapor compression. 
—Absorption. 
—Thermoelectric. 
Vapor compression systems currently employed 
in submarines are subject to leakage of refrigerant 
vapors at seals, valves, pipe joints, and control con- 
nections. Absorption systems, such as the lithium 
bromide type generally used, are extremely heavy 
and bulky and have a low coefficient of perform- 
ance. Both the vapor compression unit and the 
absorption system use refrigerants hazardous to 
personnel. 
For example, Freon becomes a personnel haz- 
ard at concentrations of 250 parts per million or 
higher. If not removed by the atmospheric control 
system, these vapors can contaminate the atmos- 
phere during long periods of submergence. Fur- 
ther, Freon also can break down into more 
harmful compounds in the presence of such high 
temperature sources as cigarettes, galley ranges, 
and pyrolytic burners. 
Various internal systems convert energy to 
heat, which is ejected into the internal hull 
atmosphere. The heat must be passed overboard to 
the sea, and since many heat sources may be 
localized, the associated heat removal devices may 
be localized. 
The magnitude of heat rejection associated with 
fixed and variable heat loads must be determined. 
Fixed heat loads are generated by internal systems 
which are required for performance of mission 
functions but are essentially independent of crew 
life support requirements. Included are radiation, 
convection, and conduction from hot piping, 
machinery, and electrical and electronic equip- 
ment. 
Variable heat loads are generated principally by 
life support functions. These include heat from the 
waste and water system, galley, food storage 
refrigeration, laundry and showers, metabolic 
water condensation, body heat, carbon dioxide 
absorbing equipment, and the oxygen recovery 
and supply equipment. 
One approach to designing the heat rejection 
system is to eject all waste heat to the sea through 
a single heat exchanger. An intermediate coolant 
can be used to collect waste heat from the various 
