TM 5-1940-321-13&P
( 1 ) Valve Design (Figure 3-4). The design of the intercommunicating valve allows
air, or CO2, to be equally distributed into all main air chambers of the craft
through a single valve. The intercommunicating valve consists of these
principal parts: the flywheel, the metal valve insert, the valve cover, the metal
valve cap, and the valve cap stowage pouch.
( 2 ) Valve Function. Figure 3-5 illustrates the different valve positions that can be
selected and the function of each position. The position of the indicating arrow
on the valve flywheel determines the mode in which the intercommunicating
valve functions. The intercommunicating valve insert has a small diaphragm
that allows air to enter for a inflation and prevents air from rushing out quickly
but permits a small airflow until the valve cap is tightened. When installed, the
valve cap, with its gasket, provides total air tightness. With the cap removed,
the small airflow past the diaphragm allows pressure readings to be taken with
the pressure gauge. The intercommunicating valves function as gates to allow
air to flow between each air chamber. They may be repositioned to seal the air
pressure in each individual air chamber. An additional function of the
intercommunicating valves is to release dangerous overpressure in the air
chambers. An overpressure release mechanism self-activates when air
pressure reaches approximately 700/800 mb (10.2 to 11.6 psi). This releases
excess air pressure, preventing unnecessary stress on the air chambers.
Figure 3-5. Intercommunicating Valve Positions and Functions.
3-5
