TM
3-4240-309-20&P
Section Ill PRINCIPALS OF OPERATION
components in the compartment control
1-11. AIR FILTERING AND PRESSURIZATION
modules in vans 1 and 4 automatically adjust the
SYSTEM.
associated airflow valves to maintain positive pressure
a. Four M87 Gas-Particulate Filter Units remove
in all four vans.
toxic gases and dust from the air supplied to four
b. The M10 Protective Entrances provide
vans and two M10 Protective Entrances. The airflow
pressurized transition areas between the vans (1 and
valves on the gas-particulate filter units on vans 2
4) and the outside contaminated zone. A balance
and 3 remain in the wide open position. The fans on
hose between the two protective entrance airduct
vans 2 and 3 draw outside air through the inlet caps
hoses ensures balanced pressurization between the
and dust separators and force the air into the filter
two protective entrances. Personnel entering from the
units. The fans force all of their filtered air into the
outside must wait 5 minutes within either of the
vans. The fans on vans 1 and 4 draw outside air
protective entrances before entering van 1 or 4.
through the inlet caps and dust separators and force
Contamination is purged by the flow of the filtered
it into the filter units. The fans force cleaned air
air. The protective entrance control modules
from the filter units into the airflow valves. The
automatically adjust the airflow valve and silencer
airflow valves direct the filtered air to the vans and
assemblies to maintain the proper air pressure inside
the M10 Protective Entrances. Airduct hoses carry
the protective entrances and contain purge timers
the filtered air through airflow valves and silencers at
and low pressure warning indicators.
each protective entrance. Filtered air enters each van
through air conditioners. The pressure sensing
1-9/(1-10
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