G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
G05D7/00—Control of flow
G05D7/01—Control of flow without auxiliary power
G05D7/0146—Control of flow without auxiliary power the in-line sensing element being a piston or float without flexible member or spring
G—PHYSICS
G01—MEASURING; TESTING
G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
G01F15/00—Details of, or accessories for, apparatus of groups G01F1/00 - G01F13/00 insofar as such details or appliances are not adapted to particular types of such apparatus
G01F15/02—Compensating or correcting for variations in pressure, density or temperature
G01F15/04—Compensating or correcting for variations in pressure, density or temperature of gases to be measured