anticipate increased symptoms associated with the drying of respiratory membranes among individuals working in these spaces.
Heating designs for submarines differ from those of surface vessels in that they provide regulated humidity for the living and control spaces noted above. Aboard submarines the temperatures should be as follows: DBT: 79°F, WBT: 59°F, RH: 50 percent, WBGT: 63°F (as ET).
With the exception of the above, inside working spaces are usually maintained at lower temperatures, depending on the amount of physical exertion required of personnel working in those areas. These temperatures will be the minimum consistent with comfort.
VENTILATION
The purpose of ventilation is to remove toxic substances, offensive odors, and excessive heat and moisture, and to provide an adequate oxygen supply. Ventilation aboard ship is designed not only to prevent conditions that could lead to acute overheating, but also to maintain an atmosphere conducive to the physical and mental efficiency of personnel. It should be effective during normal operations and in the event of CBR warfare. Ventilation systems must be as flexible as heating systems. Hot weather cooling of given spaces by ventilation is planned so that the temperature within those spaces will remain below specified limits. These limits are determined by using as a base the highest anticipated hot weather (outside) temperature. For planning purposes this is defined as 90°F DBT and 81°F WBT.
Air circulation within compartments must be sufficient to eliminate “dead spaces.” An adequate air exchange will ensure removal of odors and prevent the accumulation of moisture on environmental surfaces. Ventilation exhaust from sanitary spaces, food preparation and dining areas, sculleries, and garbage disposal areas must not be recirculated or introduced into other spaces. Ventilation of food preparation and laundry spaces must be balanced to provide a negative pressure within these areas to allow for a net inflow of air.
Cooling by ventilation is the process of diluting inside air with cooler outside air. It may prove of value aboard a ship in limiting excessive temperature from varied indoor sources (personnel, lighting, laundry equipment, machinery, poorly insulated piping in firerooms and enginerooms, etc.).
Obviously, ventilation alone will not usually cool spaces to a temperature as low as that of outside air. Firerooms and enginerooms require spot cooling, because these spaces produce so much “wild heat” that it is practically impossible to reduce the temperature of the entire space to that of a good working atmosphere. This method of cooling is accomplished by air supplied at a high velocity from ventilation ducts that concentrate their discharge on the watch stander’s station. It maintains the immediate vicinity within the acceptable range despite the high temperature of the general area.
Keeping the ventilation system clean is very important. As the adhering material accumulates, the capacity of the system to deliver air is reduced. Establish a cleaning schedule for the system, with screens, heaters, and cooling coils receiving special attention.
AIR CONDITIONING
Mechanical cooling and dehumidifying of air aboard naval vessels is accomplished by passing air over coils and fins cooled with a refrigerant. As the warm humid air circulates over the coils, it loses heat and the moisture condenses on the fins. The conditioned air is then circulated through a ducting system to appropriate spaces and compartments. Cooling coils may be located in an air supply duct with the refrigerating unit and fan placed remotely, or the entire apparatus may be assembled into a single unit.
Air conditioning is frequently required in spaces containing precision instruments sensitive to extremes of temperature and humidity. Appropriate filtering will ensure air purity within required tolerance limits.
Mechanical cooling is a current feature of the living areas and office spaces of combat ships and most auxiliaries. When still commissioned, hospital ships were routinely air conditioned, with the improved recovery of patients taking precedence over the customary weight and space limitations.
“Cold shock,” defined as rapid heat loss due to increased evaporation of sweat from the skin and damp clothing, may occur in personnel passing from heated areas into air-conditioned spaces. Chills and shivering are common manifestations. Personnel in this situation experience sudden dilation of superficial blood vessels and flushing. “Cold shock” may be minimized by regulating air-conditioned spaces so that the difference in temperatures between those spaces
