Flow measurement

Claim 1

APPARATUS FOR MEASURING FLOW RATE OF A FLUID STREAM COMPRISING, IN COMBINATION, A MAGNETIC PARTICLE ADAPTED TO BE INSERTED IN SAID STREAM AND TRANSPORTED WITH THE FLUID THEREOF, A FIXED-LENGTH SECTION OF SUBSTANTIALLY NONMAGNETIC CONDUIT DISPOSED TO CONDUCT SAID FLUID STREAM THERETHROUGH AND HAVING A PROXIMAL END AND A DISTAL END, FIRST MEANS AT THE PROXIMAL END OF SAID FIXED-LENGTH SECTION TO SENSE THE PROXIMAL END PASSAGE OF SAID MAGNETIC PARTICLE AND TO DEVELOP A FIRST SIGNAL AT THE TIME OF SAID PROXIMAL END PASSAGE, SECOND MEANS AT THE DISTAL END OF SAID FIXED-LENGTH SECTION TO SENSE THE DISTAL END PASSAGE OF SAID MAGNETIC PARTICLE AND TO DEVELOP A SECOND SIGNAL AT THE TIME OF SAID DISTAL END PASSAGE, SAID FIRST AND SECOND SIGNAL DEVELOPING MEANS BEING SEPARATED BY A PRESELECTED DISTANCE ALONG SAID CONDUIT SECTION ACCORDING TO THE FIXED LENGTH THEREOF, A THYRATRON CIRCUIT HAVING AT LEAST ONE CONTROL GRID RESPONSIVE TO SAID SIGNALS AND A PLATE CIRCUIT RELAY HAVING CONTACTS ADAPTED TO SEQUENTIALLY INITIATE AND STOP ELECTRICAL TIMING ACTION AND AN ELECTRICAL TIMER IN CIRCUIT WITH SAID RELAY ADAPTED TO INDICATE ELAPSED TIME BETWEEN SAID SIGNALS.