Abstract: An automatic pressure regulator comprises an expansion chamber, a rod reciprocable in the expansion chamber and carrying two valves, one of the valves regulating the entry of compressed air into the expansion chamber and the other of the valves regulating communication between the expansion chamber and the ambient air. A utilization air conduit is provided for connecting the expansion chamber to a measuring device. A diaphragm connected to the valve rod is moved by pressure in a regulating chamber that communicates with a pilot conduit that in turn communicates between the ends of a pilot air conduit which receives compressed air at one end, for example from the expansion chamber, and at its other end is opened or closed by a float valve in one leg of a manometer whose other leg communicates with the air utilization conduit.

Abstract: Apparatus for monitoring and regulating carburetors and other gasoline consumption devices comprises a first conduit, means for feeding test liquid under pressure to the first conduit, a flowmeter, an auxiliary reservoir, a first valve in the first conduit for selectively directing the flow of liquid either directly from the source of liquid to the flowmeter or from the auxiliary reservoir to the flowmeter, and a float valve and a check valve for arresting the flow of liquid to the auxiliary reservoir when the auxiliary reservoir is full. A second conduit is provided, for air under pressure, with a pressure regulator in the second conduit, a second valve in the second conduit coupled to the first valve and so arranged that the second valve is open when the first valve is in the position in which the flow meter is fed from the auxiliary reservoir and is closed when the first valve is in a position that the flowmeter is fed directly from the source of fluid under pressure.