Compensating device for gas flowmeters

Claim 1

IN A CONDUIT HAVING A PRESSURE-REDUCING RESTRICTION THEREIN AND HAVING AN UPSTREAM PASSAGEWAY MEANS AND A DOWNSTREAM PASSAGEWAY MEANS COMMUNICATING AT ONE END OF EACH WITH THE INTERIOR OF THE CONDUIT ON THE UPSTREAM AND DOWNSTREAM SIDES, RESPECTIVELY, OF THE RESTRICTION AND AT THE OTHER END OF EACH WITH THE INLET AND OUTLET, RESPECTIVELY, OF A DEVICE FOR MEASURING DIFFERENTIAL FLUID PRESSURE AS A MEASURE OF THE RATE OF FLOW OF FLUID IN THE CONDUIT; THE IMPROVEMENT COMPRISING BYPASS MEANS HAVING A PASSAGEWAY THERETHROUGH COMMUNICATING AT OPPOSITE ENDS BETWEEN SAID UPSTREAM AND DOWNSTREAM PASSAGEWAYS AND HAVING A POT IN SAID BYPASS PASSAGEWAY, AN OBTURATOR MOVABLE ACROSS THE PORT TO VARY THE SIZE OF THE PORT, A SEALED CHAMBER CONTAINING A QUANTITY OF A REFERENCE GAS SUBJECT TO SUBSTANTIALLY THE SAME TEMPERATURE AND PRESSURE CONDITIONS AS THE FLUID FLOWING IN SAID CONDUIT, ONE WALL OF SAID REFERENCE CHAMBER BEING FLEXIBLE DIAPHRAGM AND MEANS INTERCONNECTING SAID FLEXIBLE DIAPHRAGM AND SAID OBTURATOR FOR MOVEMENT IN A SENSE SUCH THAT MOVEMENT OF THE DIAPHRAGM UPON EXPANS ON OF THE VOLUME OF SAID SEALED CHAMBER MOVES SAID OBTURATOR IN A DIRECTION TO OPEN THE PORT AND MOVEMENT OF THE DIAPHRAGM IN THE OPPOSITE DIRECTION MOVES THE OBTURATOR IN A DIRECTION TO CLOSE THE PORT SO THAT A CHANGE IN THE DENSITY OF THE FLUID FLOWING IN SAID CONDUIT IS ACCOMPANIED BY AN INVERSE CHANGE IN THE VOLUME OF FLUID FLOWING THROUGH SAID BYPASS PASSAGEWAY.