Ultrasonic flow metering
Embodiments include a novel, easy to install, non-intrusive, ultrasonic water flow meter with a self-calibrating three-piezoelectric transducer configuration attached externally to a water pipe, that allows for accurate measurement of water flow, and can provide the flow data to a remote system for billing and further analysis. The water flow data can further be analyzed for water consumption by individual fixtures, in support of conservation and usage management efforts.
1. An ultrasonic flow meter, the ultrasonic flow meter comprising:
a clamp-on carrier assembly configured to be externally mounted on a pipe, wherein a medium intermittently has a direction of flow through the pipe;
at least three ultrasonic transducers, mounted to the clamp-on carrier assembly, wherein:
two or more of the at least three ultrasonic transducers are configured to perform at least one of:
transmitting ultrasonic acoustic waves that propagate at oblique angles relative to the direction of flow through the pipe of the medium; or
sensing ultrasonic acoustic waves that propagate at oblique angles relative to the direction of flow through the pipe of the medium; and
one or more of the at least three ultrasonic transducers is configured to perform at least one of:
transmitting ultrasonic acoustic waves that propagate at right angles relative to the direction of flow through the pipe of the medium; or
sensing ultrasonic acoustic waves that propagate at right angles relative to the direction of flow through the pipe of the medium; and
a processing system, mounted to the clamp-on carrier assembly, that is configured to perform an auto-discovery and self-calibration process comprising:
obtaining a first set of measurements, wherein:
obtaining the first set of measurements comprises using a plurality of different pairings of the at least three ultrasonic transducers to transmit and sense a plurality of ultrasonic acoustic waves; and
the first set of measurements are obtained, when the medium is not flowing, based on a subset of the plurality of ultrasonic acoustic waves; and
calibrating the processing system, based on the first set of measurements,
wherein the calibrating comprises;
generating, based on the first set of measurements, one or more calibration factors for calculating a distance that a given ultrasonic acoustic wave travels when the medium is flowing; and
calibrating the process system based on the one or more calibration factors and one or more additional sets of measurements, obtained when the medium is flowing, using the at least three ultrasonic transducers.
2. The ultrasonic flow meter of claim 1 , wherein:
the medium is water;
the at least three ultrasonic transducers comprise piezoelectric transceivers; and
the first set of measurements comprises time of flight measurements, from transmission to sensing, for corresponding ultrasonic acoustic waves.
3. The ultrasonic flow meter of claim 2 , wherein calibrating the processing system further comprises:
detecting tampering based, at least in part, on detecting an absence of ultrasonic acoustic waves travelling along an exterior surface of the pipe.
4. The ultrasonic flow meter of claim 3 , wherein, when tampering is detected, calibrating the processing system further comprises at least one of:
generating a user alert in response to the detected tampering; or
entering a low power state in response to detecting the absence of the ultrasonic acoustic waves travelling along the exterior surface of the pipe.
5. The ultrasonic flow meter of claim 2 , wherein:
the ultrasonic flow meter further comprises at least one temperature sensor mounted to the clamp-on carrier assembly; and
the at least one temperature sensor is configured to be coupled to the pipe when the clamp-on carrier assembly is externally mounted on the pipe.
6. The ultrasonic flow meter of claim 5 , wherein:
the processing system is further configured to measure the flow:
based on the time of flight measurements; and
by applying temperature compensation;
the first set of measurements comprises temperature measurements obtained from the at least one temperature sensor; and
the temperature compensation, based on the temperature measurements, eliminates dependence on temperatures of the medium when measuring the flow of the medium.
7. The ultrasonic flow meter of claim 6 , wherein the ultrasonic flow meter further comprises at least one of:
a battery module capable of supplying power to the processing system and a memory configured to store the first set of measurements and the one or more additional sets of measurements, wherein the battery module and the memory operate remotely from the processing system;
a display device, wherein the display device is:
operating remotely from the processing system; and
configured to display information based at least in part on measured flow for the medium; or
a communication interface.
8. The ultrasonic flow meter of claim 1 , wherein calibrating the processing system further comprises calculating, based on the one or more calibration factors and the one or more additional sets of measurements, at least one of:
a cross-section area for an inner area of the pipe;
an average travel length for individual ultrasonic waves propagating through the medium; or
an average incidence angle for individual ultrasonic waves propagating through the medium.
9. The ultrasonic flow meter of claim 1 , wherein:
the clamp-on carrier assembly is modifiable to fit a plurality of pipe sizes; and
calibrating the processing system further comprises determining at least one of a size of the pipe or a material of the pipe based on the one or more calibration factors and the one or more additional sets of measurements.
10. The ultrasonic flow meter of claim 1 , wherein obtaining the first set of measurements comprises using every potential pairing of the at least three ultrasonic transducers for transmitting and sensing the plurality of ultrasonic acoustic waves.
11. A method for calibrating an ultrasonic flow meter, the method comprising:
obtaining, from at least three ultrasonic transducers, a first set of measurements, wherein:
the at least three ultrasonic transducers are mounted, along with a processing system performing the method, to a clamp-on carrier assembly configured to be externally mounted on a pipe;
a medium intermittently has a direction of flow through the pipe;
two or more of the at least three ultrasonic transducers are configured to perform at least one of:
transmitting ultrasonic acoustic waves that propagate at oblique angles relative to the direction of flow through the pipe of the medium; or
sensing ultrasonic acoustic waves that propagate at oblique angles relative to the direction of flow through the pipe of the medium;
one or more of the at least three ultrasonic transducers is configured to perform at least one of:
transmitting ultrasonic acoustic waves that propagate at right angles relative to the direction of flow through the pipe of the medium; or
sensing ultrasonic acoustic waves that propagate at right angles relative to the direction of flow through the pipe of the medium;
obtaining the first set of measurements comprises using a plurality of different pairings of the at least three ultrasonic transducers to transmit and sense a plurality of ultrasonic acoustic waves; and
the first set of measurements are obtained, when the medium is not flowing, based on a subset of the plurality of ultrasonic acoustic waves; and
generating, based on the first set of measurements, one or more calibration factors for calculating a distance that a given ultrasonic acoustic wave travels when the medium is flowing; and
calibrating the processing system based on the one or more calibration factors and one or more additional sets of measurements, obtained when the medium is flowing, using the at least three ultrasonic transducers.
12. The method of claim 11 , wherein:
the medium is water;
the at least three ultrasonic transducers comprise piezoelectric transceivers; and
the first set of measurements comprises time of flight measurements, from transmission to sensing, for corresponding ultrasonic acoustic waves.
13. The method of claim 12 , wherein calibrating the processing system further comprises detecting tampering based, at least in part, on detecting an absence of ultrasonic acoustic waves travelling along an exterior surface of the pipe.
14. The method of claim 13 , wherein, when tampering is detected, calibrating the processing system further comprises at least one of:
generating a user alert in response to the detected tampering; or
entering a low power state in response to detecting the absence of the ultrasonic acoustic waves travelling along the exterior surface of the pipe.
15. The method of claim 12 , wherein:
at least one temperature sensor is mounted to the clamp-on carrier assembly; and
the at least one temperature sensor is configured to be coupled to the pipe when the clamp-on carrier assembly is externally mounted on the pipe.
16. The method of claim 15 , further comprising measuring the flow, wherein:
measuring the flow is performed:
based on the time of flight measurements; and
by applying temperature compensation;
the first set of measurements comprises temperature measurements obtained from the at least one temperature sensor; and
the temperature compensation, based on the temperature measurements, eliminates dependence on temperatures of the medium when measuring the flow of the medium.
17. The method of claim 16 , wherein the at least three ultrasonic transducers are appended to an ultrasonic flow meter that further comprises at least one of:
a battery module capable of supplying power to the processing system and a memory configured to store the first set of measurements and the one or more additional sets of measurements, wherein the battery module and the memory operate remotely from the processing system;
a display device, wherein the display device is:
operating remotely from the processing system; and
configured to display information based at least in part on measured flow for the medium; or
a communication interface.
18. The method of claim 11 , wherein calibrating the processing system further comprises calculating, based on the one or more calibration factors and the one or more additional sets of measurements, at least one of:
a cross-section area for an inner area of the pipe;
an average travel length for individual ultrasonic waves propagating through the medium; or
an average incidence angle for individual ultrasonic waves propagating through the medium.
19. The method of claim 11 , wherein:
the clamp-on carrier assembly is modifiable to fit a plurality of pipe sizes; and
calibrating the processing system further comprises determining at least one of a size of the pipe or a material of the pipe based on the one or more calibration factors and the one or more additional sets of measurements.
20. The method of claim 11 , wherein obtaining the first set of measurements comprises using every potential pairing of the at least three ultrasonic transducers for transmitting and sensing the plurality of ultrasonic acoustic waves.