PART A - INTRODUCTION AND MAJOR COMPONENTS OF THE
NBC PROTECTION SYSTEM, M1A1 SERIES TANK
The M1A1 series tank has two separate NBC protection systems; the
main system and backup system.
a. The NBC Backup System.
The tank crew uses this system only
when the main NBC system fails to operate.
The backup NBC system
provides decontaminated air to the tank with or without the engine
running. The backup system does not produce as much air as the main
NBC system; however, it does produce enough air to protect the crew
when they wear their protective masks.
(Crew members use the air-
cooled vest with the main NBC system only.)
The NBC backup system draws air from outside the tank. When the crew
turns on the backup system, the fresh air valve opens and the
particulate blower draws air into the ductwork and through the
The filtered air then flows into the main NBC
ductwork where the fresh air heater warms the air if necessary.
NBC system used in the M1A1 tank, less the heaters and turret blower.
b. The Main NBC System (fig. 1-1). The main NBC system provides
dry, temperature-controlled, filtered air to the crew compartment and
individual crew member air outlets.
For the main NBC system to
operate, the crew must have the tank's engine running. The main NBC
system automatically turns on after starting the engine, and the crew
may turn off the system from one of the following locations:
The commander's control panel using the MAIN NBC MODE
Additionally, this panel controls the temperature
of the filtered air between 43,F to 120,F (fig. 1-2).
The gunner's primary sight using the GUN SELECT switch.
The loader's panel using the TURRET BLOWER switch.
With the engine running at tactical idle and the gun breech open, the
main NBC system provides a total of 200 cubic feet per minute (cfm)
of filtered air, at 35 pounds per square inch (psi).
air goes to each of the following outlets: