Section III. HEATED STORAGE

TM 38-260

(3) Indoor metal hutments will last indefinitely because they are not exposed to outside weather conditions.

Some of their advantages over plastic film hutments are:

(a)

Walk-in type door.

(b)

Removable roof sections for egress and ingress of heavy equipment with the use of overhead cranes.

(c)

Impervious to tearing.

(d)

Potential for reutilization.

Section III. HEATED STORAGE

5-9.

General

a. Heated Storage. This method of control is adaptable to most manufacturing buildings and warehouses where an

adequate heating system is already installed. A 20F (11.1C) rise in temperature doubles the capacity of the storage

air to hold water vapor. For example, if the temperature in a storage enclosure is 60 F (11.1 C) and the relative

humidity is 90 percent, by heating the storage atmosphere to 80F (26.7C), the relative humidity would be lowered to

45 percent. This type of control is used to maintain a maximum of 50 percent relative humidity in the storage area to

prevent moisture vapor from condensing on the surfaces of production equipment. This may be accomplished by

automatically controlling the heating system with a humidistat connected in parallel with an adjustable room thermostat.

The humidistat and the thermostat should be installed approximately 5 feet above the floor level to avoid temperature

variations. The humidistat will be set to activate the heating system at a temperature 2 F below maximum dew point

temperature, which can be obtained at the local library or weather service. As long as the humidity is 50 percent or more,

the heating system will be activated by the humidistat, but when the humidity is below 50 percent and the temperature

drops to 2F below the maximum dew point temperature, the thermostat will close and activate the heating system.

b. The use of heat for control of relative humidity may not be economically feasible for those facilities for which the

cost of comfort heating is excessive. Buildings need not be vapor sealed for effective heat control; however, reasonable

efforts should be made to prevent unnecessary heat loss.

5-10.

Geographical Locations

a. There are some geographic areas in the United States where IPE is unlikely to corrode either from high humidity

or condensation during certain months of the year. for example, in Phoenix, Arizona, heat would be required January and

February only.

b. For those installations where heat has been discontinued during the temperate seasons, ventilation may be

accomplished as follows:

5-16