TM 3-4240-313-10 OPERATOR'S MANUAL SIMPLIFIED ...

TM 3-4240-313-10
Section III. PRINCIPLES OF OPERATION
1-12. SYSTEM DESCRIPTION.
a. To provide NBC protection, a higher pressure must exist inside the shelter than outside the shelter. The airflow
that causes the pressure must pass through the HSFC. Small leaks in the shelter liner will have no effect as long as
pressure is maintained inside shelter.
b. When the system is pressurized, almost all airflow into shelter will flow through PE to the contaminated exterior.
c. The blower inflates the shelter to a pressure of 0.6 iwg. Vents between shelter and PE are adjusted for pressure
of 0.6 iwg in shelter, and vents between PE and outside are adjusted for pressure of 0.25 iwg in PE. Clean air flowing
from shelter to outside through PE purges toxic vapors from PE.
1-13. FUNCTIONAL DESCRIPTION OF MAJOR COMPONENTS.
a. Motor Blower. The blower provides a minimum of 200 cubic feet of air per minute to the protective shelter
through the HSFC. It will operate on 110/220 VAC 50/60 Hz. Blower assembly provides electrical power for extension
light and PE dome light through output connector J2 to the PE power supply.
b. Hermetically Sealed Filter Canister (!SFC). This filter removes toxic chemical agents, biological agents, and
radioactive particles from air passing through it.
c. Air Ducts. The air ducts provide airflow path for air from blower through HSFC into shelter.
d. Recirculation Filter. The recirculation filter removes residual toxic agents which may be present inside the
SCPE liners. The recirculation filter blower motor operates from any 115 VAC 50/60 Hz electrical source.
e. Room Liner. Room liners are cylindrical in shape and are inflated with filtered air from HSFC and blower.
The inflated room liners provide a place to work or rest without having to wear protective clothing.
f. Protective Entrance (PE). PE allows personnel to move from contaminated area into liner without introducing
contaminants into protected area.
g. Differential Pressure Gages. There are two gages that read from 0 iwg to 2.0 iwg. One is mounted on liner
side of PE and measures difference in pressure between inside liner and outside. Another is mounted to inside wall of
PE and measures difference in pressure between inside PE and outside. The gages are used when adjusting internal
pressures in shelter and PE. An adjusting tool is provided to adjust gages before operation.
h. Vents Two vents near the bottom of the two outer PE walls are used to adjust PE pressure. Two vents near the
top of the liner side of PE wall are used to adjust shelter pressure. PE and shelter pressure can be regulated by adjusting
these vents.
i. Dome Light. There is one dome light mounted to the ceiling of the PE which operates at 28 VAC supplied by
PE power supply.
j. Interval Timer. A mechanical five-minute bell timer is mounted on the wall of the PE. It is used to time the
purge period of personnel entering the SCPE from contaminated areas.
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