Autoranging sonic flowmeter
AssigneeNusonics, Inc.
InventorsTheodore N. Birnbaum, Ellis M. Zacharias, Jr.
Life of this patent
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Abstract
A system for measuring the flow of a fluid in a pipe that is one of a plurality of different sizes. The system employs a pair of transducers mounted on the pipe in an upstream-downstream relationship, Each transducer is excited by one of a pair of oscillators to transmit a sonic signal though the fluid to the other transducer. Transit times of the sonic signals are measured. A microprocessing network computes the flow rate of the fluid based on the measured transit time in the pipe. The system has a signal transit time between transducers equal to the time elapse of N cycles of the frequency emitted by the oscillators. The value of N, as computed by a microprocessor, relates to the size of the pipe.
Claims21
For use with a system for measuring the flow of a fluid in a pipe wherein a pair of transducers is mounted on the pipe in an upstream-downstream relationship, each transducer being excited by one of a pair of oscillators to transmit a sonic signal through said fluid in said pipe to the other of said transducers, the improvement comprising:
- a pair of transducer mounting sleeves extending outwardly from said pipe providing communication with the interior of said pipe;
- a pair of acoustic window means, one disposed in each of said sleeves for hydraulically isolating said transducers from said fluid in said pipe for passing said transducer sonic signals through said pipe;
- and
- a microprocessing network adapted for measuring the flow of said fluid of said pipe selected from a plurality of pipe sizes, each pipe size having a different inner diameter, said system having a signal transit time between transducers exactly equal to the time elapse of N cycles of a frequency emitted by said oscillators, wherein the value of N is computed by the microprocessor from transmit time data and relates to the size of the pipe.
For use with a system for measuring the flow of a fluid in a pipe wherein a pair of transducers is mounted on the pipe in an upstream-downstream relationship, each transducer being alternately excited by one of a pair of oscillator to transmit a sonic signal through said fluid in said pipe to the other of said transducers, the improvement comprising:
- a pair of transducer mounting sleeves extending outwardly from said pipe providing communication with the interior of said pipe;
- a pair of acoustic window means, one disposed in each of said sleeves for hydraulically isolating said transducers from said fluid in said pipe and for passing said transducer sonic signals through said pipe;
- a microprocessor network having means for generating a threshold signal of variable level;
- means for selecting a level of said threshold signal;
- means for receiving electrical output signals from each of said transducers operating as receivers;
- means for comparing said received output signals with said selected threshold level to determine the moment said transducer is excited by an incoming acoustic pulse;
- means for filtering said electrical output signals and selecting the optimal sinusoidal peak, said selected threshold level being at approximately the level of a midpoint between a positive peak level of said optimal sinusoidal peak and a positive peak level of its immediately preceding cycle;
- means for counting the number of cycles of said transmit signal which precede said optimal sinusoidal peak;
- means for multiplying said number of cycles counted by said counting means by approximately the average time of a cycle to determine a delay time;
- and
- means for determining an average transit time of said transducer sonic signals in both directions between said transducers and means for subtracting said delay time from said average transit time to determine an ideal no flow time that is employed in said microprocessor network for determining the rate of flow of said fluid in said pipe,
- wherein said microprocessing network is adapted for measuring the flow of fluid in a pipe selected from a plurality of pipe sizes, each pipe size having a different inner diameter, said system having a signal transit time between transducers exactly equal to the time elapse of N cycles of a frequency emitted by said oscillators, wherein the value of N is computed by the microprocessor from transmit time data and relates to the size of the pipe.
Dependencies are inferred from the claim text.