System for measuring characteristics of fluids

Claim 1

APPARATUS FOR DETERMINING THE VELOCITY OF A FLUID FLOWING THROUGH A CONDUIT COMPRISING: TRANSMITTING MEANS DISPOSED IN SAID CONDUIT FOR INTRODUCING AN ACOUSTIC SIGNAL INTO THE FLUID, RECEIVING MEANS DISPOSED IN SAID CONDUIT AND SPACED ALONG THE AXIS OF FLOW FROM SAID TRANSMITTING MEANS FOR RECEIVING THE ACOUSTIC SIGNAL AFTER PASSAGE THROUGH THE FLUID, PHASE COMPARING MEANS RESPONSIVE TO SAID TRANSMITTING MEANS AND SAID RECEIVING MEANS FOR MEASURING THE PHASE ANGLE BETWEEN THE TRANSMITTED SIGNAL AND THE RECEIVED SIGNAL AND PRODUCING A FIRST ELECTRICAL SIGNAL HAVING A MAGNITUDE PROPORTIONAL TO SAID PHASE ANGLE, MEANS FOR MEASURING THE VELOCITY OF PROPAGATION OF THE ACOUSTIC SIGNAL IN THE FLUID AND PRODUCING A SECOND ELECTRICAL SIGNAL PROPORTIONAL THERETO, AND MEANS RESPONSIVE TO BOTH SAID FIRST AND SECOND ELECTRICAL SIGNALS TO PROVIDE A REPRESENTATION OF THE ACTUAL VELOCITY OF THE FLUID FLOWING IN SAID CONDUIT BETWEEN SAID TRANSMITTING MEANS AND SAID RECEIVING MEANS, SAID LAST RECITED MEANS INCLUDING: A POTENTIOMETER CONSTITUTED BY A FIRST FIXED RESISTANCE AND A FIRST MOVABLE CONTACT, MEANS FOR APPLYING THE SECOND ELECTRICAL SIGNAL ACROSS THE FIRST FIXED RESISTANCE OF SAID POTENTIOMETER, A MOTOR FOR POSITIONING SAID FIRST MOVABLE CONTACT, AND MEANS FOR BALANCING SAID FIRST ELECTRICAL SIGNAL AGAINST THE PORTION OF SAID SECOND ELECTRICAL SIGNAL PRESENT ACROSS THE PORTION OF SAID FIRST RESISTANCE BETWEEN ONE END THEREOF AND SAID FIRST MOVABLE CONTACT, SAID MOTOR BEING RESPONSIVE TO SAID BALANCING MEANS TO ACTUATE SAID FIRST MOVABLE CONTACT UNTIL SAID FIRST SIGNAL AND SAID PORTION OF SAID SECOND SIGNAL ARE BALANCED, WHEREBY VARIATIONS IN THE FIRST SIGNAL CAUSED BY VARIATIONS IN SAID PROPAGATION VELOCITY ARE COMPENSATED AND THE POSITION OF SAID MOVABLE CONTACT IS REPRESENTATIVE OF THE ACTUAL VELOCITY OF THE FLUID FLOWING BETWEEN SAID TRANSMITTING MEANS AND SAID RECEIVING MEANS.