TM 9-4120-411-14
Section IV. OPERATION UNDER UNUSUAL CONDITIONS
2.6 GENERAL. Follow instructions given in Section III, Operation Under Usual Conditions.
2.7 UNUSUAL ENVIRONMENTS AND WEATHER.
Notify unit maintenance personnel for assistance if necessary to
perform any of the following tasks.
2.7.1 Extreme Heat. Open and close the shelter as little as possible. If fresh outside make-up air is not required, slip
return air duct over perforations on unit return air duct adapter. Seal any openings in shelter. Do not try to maintain a
shelter temperature any lower than is necessary. Be sure there are no obstructions to airflow through FDECU. Provide
shade over unit if possible but do not obstruct air flow.
CAUTION
Extreme cold can cause electrical wire leads and insulation to become brittle. Do
not disturb electrical wiring that has been exposed to extremely low temperatures.
Damage to electrical wire leads or insulation can result if disturbed under these
conditions.
2.7.2 Extreme Cold. Open and close the shelter as little as possible. If fresh outside make-up air is not required, slip
return air duct over perforations on unit return air duct adapter. Seal any openings in shelter. Do not try to maintain a
shelter temperature any higher than is necessary. The unit will periodically defrost ice from the outside coil. When this
happens, water will drain from the unit bottom and could cause ice build up if it collects there. It may be necessary to
raise the unit to prevent the collection of water under the unit.
2.7.3 Salt Air or Sea Spray. The FDECU requires no special protection procedures against salt air or sea spray,
however, it is advisable to clean the unit more frequently than under normal conditions. If fresh outside make-up air is not
required, slip return air duct over perforations on unit return air duct adapter. Check and clean the return air filter more
frequently.
2.7.4 Dust Storm or Sand Storm. The FDECU requires no special protection procedures against dust or sand storms,
however, it is advisable to clean the unit more frequently than under normal conditions. If fresh outside make-up air is not
required, slip return air duct over perforations on unit return air duct adapter. Check and clean the return air filter more
frequently.
2.7.5 Snow. The FDECU requires no special protection procedures against snow, however, the snow should not be
allowed to build up around the unit and obstruct airflow. The unit will periodically defrost ice from the outside coil. When
this happens, water will drain from the unit bottom and could cause ice build up if it collects there. It may be necessary to
raise the unit to prevent the collection of water under the unit.
2.8 NUCLEAR, BIOLOGICAL, AND CHEMICAL (NBC) CONDITIONS.
2.8.1 Notify unit maintenance personnel and refer them to installation instructions contained in Chapter 4, Section I for
instructions to setup the NBC kit for this condition.
2.8.2 Operate and maintain the NBC filter/blower assemblies per instructions supplied with them.
2.8.3 Seal any openings in the shelter. Open and close the shelter as little as possible.
Follow decontamination
procedures per paragraph 2.9 as necessary when entering and leaving the shelter.
2-11