9. Q. With the feed valve adjusted at seventy pounds, and the regulating spring at twenty pounds, what pressure will be had in the main reservoir when the governor stops the compressor?
A. Ninety pounds.
10. Q. Explain the operation of the governor in controlling the compressor when a main reservoir pressure of ninety pounds is reached.
A. When the main reservoir pressure in chamber "d" slightly exceeds the pressure on top of the diaphragm it will move upward, carrying the pin valve with it. The air in chamber "d" passes by the unseated pin valve through port "b" into chamber "b" above the governor piston, forcing it downward, seating the steam valve 5, thus shutting off the steam to the compressor.
11. Q. How long will the governor remain in this position?
A. Until the main reservoir pressure falls below ninety pounds, when the combined spring and air pressure in chamber "f" will force the diaphragm 28 down, seating the pin valve. This shuts off the supply of air from chamber "d", and the air confined in chamber "b" will escape to the atmosphere through the vent port "c". The pressure now being removed from above the governor piston, the spring 9 aided by the steam pressure under the valve 5, will force the piston upward, unseating the steam valve 5, allowing steam to pass through the governor to the compressor.
12. Q. When the steam valve is seated, is steam entirely shut off from the compressor?
A. No; there is a small port drilled through the valve; its purpose is to maintain a circulation in the steam pipe and keep the compressor working slowly; thereby preventing condensation when the steam valve is closed.
13. Q. With the automatic brake valve in release, running, or holding position, does the maximum pressure head operate?
A. No; as during this time the main reservoir pressure is not sufficiently high to actuate its diaphragm.