Flow Meter Arm Deflection Sensor for Pressure Isolation
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Solution Overview
Problem
Existing flow meter designs using strain bridges to measure force on target elements in pipelines face challenges due to static differential pressure, which increases design complexity and cost, particularly for liquids where density compensation is needed, as the strain bridge must be isolated from internal pressure, complicating the positioning and measurement of induced strain.
Innovation Solution
A flow meter design that measures deflection of an arm radially extending across a conduit, using an optical sensor arrangement to detect changes in the arm's deflection caused by axial displacement of a target element, allowing for isolation of the sensor outside the conduit and eliminating the need for separate pressure measurements for density compensation, with a resilient biasing member and flexible arm configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a strain bridge is used to measure force on the target element, then the mass flow rate can be determined, but the design complexity increases due to the need to isolate the strain bridge from internal pressure
Solution Approach 1:
The patent replaces the strain bridge (electrical measurement system) with a mechanical arm deflection measurement system. The arm deflects mechanically in response to pressure differential, and this deflection is measured optically or mechanically, eliminating the need for electrical strain gauges that require pressure isolation.
Solution Approach 2:
The measurement function is extracted from the high-pressure internal environment. The arm extends through the conduit wall to a low-pressure external environment where the sensor operates, separating the sensing function from the high-pressure measurement zone and eliminating the need for complex pressure isolation of the sensor.
2Reliability
If the strain bridge is isolated from internal pressure, then the sensor can operate safely, but the positioning and measurement of induced strain becomes more difficult
Solution Approach 1:
The arm acts as an intermediary mechanical element that transmits the force from the target element through the conduit wall to the external sensor. This mechanical linkage allows the sensor to operate externally in a safe environment while still measuring the force indirectly through arm deflection.
3Force
If a resilient biasing member is added to the system, then the target element can be biased axially, but the device complexity increases
Solution Approach 1:
The resilient biasing member (such as a spring) provides self-service by automatically applying axial biasing force to the target element without requiring external control systems. The spring naturally exerts force to maintain the target element in a predetermined axial position, eliminating the need for active control mechanisms.
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
This design simplifies the flow meter by reducing the need for complex pressure compensation, enhances measurement accuracy, and provides greater design flexibility, allowing for accurate mass flow rate determination without significant error from static fluid pressure, and can be applied to various fluids and pipeline cross-sections.
Implementation Method 1
the target element being mounted for resilient axial displacement under a pressure differential between the inlet and the outlet
Implementation Method 2
the arm is flexible and the anchor point is a flexure point
Implementation Method 3
the optical sensor arrangement comprises a reflecting element fixed to the arm, a light source for directing an incident beam of light onto the surface of the reflecting element, and a light detector for detecting the position of the resulting reflected beam of light
Data Source
AI summary
A flow meter for monitoring fluid flow through a pipeline, the flow meter comprising a conduit having a fluid inlet and a fluid outlet for communication with respective sections of the pipeline; a target element positioned inside the conduit between the fluid inlet and the fluid outlet, the target element being mounted for resilient axial displacement under a pressure differential between the inlet and the outlet; an arm secured at an anchor point on one side of the conduit and extending radially across the conduit, the target element being coupled to the arm for applying a load to the arm, upon said axial displacement of the target element, so as to deflect the arm relative to the anchor point; a sensor arrangement for measuring deflection of the arm at a point on the opposite side of the applied load to the anchor point; and a processor configured for providing a signal representative of the steam flow through the conduit in response to said measured deflection.