ALTITUDE SENSING SYSTEM

This system (figure 2-9) senses the pressure (less 1 atmosphere) in the altitude chamber or suit simulator tank. In this case, we refer to atmosphere as a unit of pressure equal to 14.69 pounds per square inch. Both the high-range and low-range altimeters are operated by differential pressure. The high-range altimeter (12) senses the altitude inside the chamber through the chamber reference port (N/N). When you place the pressure selector valve (O) in the ALTITUDE CHAMBER position, the low-range altimeter senses the altitude through the same chamber reference port (N/N). The low-range altimeter also senses the pressure inside the suit simulator tank. You must place the reference pressure selector valve (O) in the SUIT SIMULATOR position and open the suit simulator reference shutoff valve (R) for the low-range altimeter to read this pressure.

PRESSURIZING THE ALTITUDE SENSING SYSTEM

When you pressurize the altitude sensing system, be sure the reference pressure selector valve (O) is in the ALTITUDE CHAMBER position and open the vacuum control valve (B1). When you open the control valve (B1), ascend to 50,000 feet. The altitude will be indicated on the high-range altimeter (12). Stabilize with control valve B1 at this altitude and check for leaks. Open chamber bleed valve (K) and return to sea level. Close valve (K) when you reach sea level. If you find that the test stand has no leaks at this point, turn the reference pressure selector valve (O) to the SUIT SIMULATOR position; then open the suit simulator reference shutoff valve (R) fully. Place the flow selector valve (M) in the SUIT SIMULATOR position. Now you are ready to ascend to altitude. Open the vacuum control valve (B1) and ascend to 35,000 feet. This altitude will be indicated on the low-range altimeter (13). Again stabilize with control valve (B1) and check for leaks. Close the vacuum control valve (B1) and return to sea level. To setup the test stand for the chamber bleed system test, close the chamber bleed valve (K). Place the reference pressure selector valve (O) in the ALTITUDE CHAMBER position; close the suit simulator shutoff valve (R) and place the flow selector valve (M) in the REGULATOR position. Leave all valves and connections in their present position.

CHAMBER BLEED SYSTEM

The chamber bleed system shown in figure 2-10 is a very simple system used to introduce a