Ultrasonic Flowmeter Self-Verification Failure Detection
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Solution Overview
Problem
Ultrasonic transit-time flowmeters in Safety Instrumented Systems face challenges in accurately detecting hardware and software failures, which can lead to false flow measurement values and potentially severe consequences, such as a gasoline storage tank overflow, due to existing diagnostic measures not providing sufficient confidence for reliable failure detection.
Innovation Solution
Incorporating a self-verification unit with reference elements, such as acoustic or electronic delay elements, that provide reference signals to an electronic controller for comparison with predetermined values, allowing the flowmeter to identify and respond to failures by indicating a faulty operating state and preventing measurement output until the issue is addressed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing diagnostic measures are used to detect failures, then the flowmeter can identify some hardware and software failures, but the detection confidence is insufficient for Safety Instrumented System applications
Solution Approach 1:
The patent changes the diagnostic approach by measuring transit time through reference elements (acoustic or electronic delay elements) and comparing it to a predetermined reference value. This parameter-based comparison method provides objective, quantifiable diagnostic data with sufficient confidence for SIS applications, rather than relying on existing subjective or less precise diagnostic measures.
Solution Approach 2:
The patent introduces reference elements (acoustic delay elements or electronic delay elements) as intermediaries to facilitate failure detection. These reference elements provide a known, stable transit time that serves as a reference standard, allowing the diagnostic system to objectively assess the health of the flow measurement path without being affected by fluid flow conditions or other variable factors.
2Reliability
If reference elements are added to the flowmeter, then failure detection capability is improved, but device complexity increases
Solution Approach 1:
The reference elements act as simple intermediary components that provide a known transit time reference. They are passive elements (acoustic delay elements or electronic delay elements) that do not require active control or complex processing, thereby adding minimal complexity to the system while significantly improving failure detection capability.
Solution Approach 2:
The reference elements create a simplified copy or model of the actual measurement path's transit time characteristics. By measuring and comparing the transit time through the reference elements to a predetermined reference value, the system can detect failures without needing to analyze the complex fluid flow dynamics, thus reducing overall system complexity.
3Reliability
If continuous monitoring of reference values is performed, then failure detection reliability is enhanced, but energy consumption increases
Solution Approach 1:
The patent implements periodic monitoring of the reference value through the reference elements, rather than truly continuous monitoring. The electronic controller compares the measured transit time through the reference elements to the predetermined reference value at regular intervals, providing sufficient failure detection reliability while allowing the system to enter lower-power states between monitoring cycles, thus reducing overall energy consumption.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables reliable detection and response to failures in ultrasonic transit-time flowmeters, ensuring accurate flow measurement and enhancing safety by preventing false outputs, thereby maintaining the integrity of the flow measurement process within Safety Instrumented Systems.
Implementation Method 1
The most common implementation of ultrasonic transducers uses a piezoelectric crystal or piezoelectric ceramic.
Implementation Method 2
The ultrasonic signal travels through the fluid and the second ultrasonic transducer receives the ultrasonic signal
Implementation Method 3
a first acoustic delay element and a second acoustic delay element, wherein the acoustic delay elements each have a different delay time
Data Source
AI summary
An ultrasonic transit-time flowmeter and a method for detecting a failure in an ultrasonic transit-time flowmeter are provided. The flowmeter includes a first ultrasonic transducer and a second ultrasonic transducer, wherein the transducers each are configured to transmit and receive signals, wherein the signals are transmitted between the transducers and measurements of transit-times of the signals and a transit-time difference based upon the transit-times are used to calculate a fluid flow velocity. Further, the flowmeter has a first reference element and a second reference element, wherein the first and second reference elements each provide a reference signal, and an electronic controller, wherein a predetermined value is stored in a memory of the controller. A reference value based upon the reference signals is compared with the predetermined value and a failure of the ultrasonic flowmeter is identified based upon a comparison of the reference value with the predetermined value.