Corrosion-Resistant Pressure Sensor for Hazardous Atmospheres
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Solution Overview
Problem
Existing pressure sensing devices fail to effectively measure both liquid and gas flows in corrosive or explosive atmospheres due to compatibility issues with electrical components, leading to instability and high costs in differential pressure sensing.
Innovation Solution
A pressure sensing device with corrosion- and explosion-proof protection using a thin, elastically deformable membrane and an explosion-proof protective tube, combined with filtering means such as Helmholtz-type resonators to remove disturbance frequencies, allowing for accurate measurement of pressure variations while preventing flame propagation and corrosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If electrical components are placed on one side of the measuring membrane for pressure sensing, then measurement capability is improved, but compatibility with corrosive or explosive atmospheres deteriorates
Solution Approach 1:
The device is divided into two separate sides: one side contains only the measuring membrane exposed to the fluid for pressure sensing, while the other side houses all electrical components (deformation sensor, amplifier, processing units). This segmentation isolates electrical components from corrosive or explosive atmospheres while maintaining measurement capability through the membrane's mechanical deformation.
Solution Approach 2:
The measuring membrane acts as an intermediary element that transmits pressure information from the fluid side to the electrical components side through mechanical deformation. It converts pressure variations into physical displacement, which is then detected by the deformation sensor, enabling indirect measurement without direct contact between electrical components and hazardous fluids.
2Measurement precision
If two identical pressure sensors are mounted back-to-back for differential pressure measurement, then measurement capability is improved, but device complexity and cost increase
Solution Approach 1:
Two pressure sensing functions are merged into a single integrated device by mounting two measuring membranes back-to-back on opposite sides of a common structural element. This allows differential pressure measurement across the device while sharing common components (structural support, sealing, housing), thereby reducing overall complexity and volume compared to using two separate sensors.
3Reliability
If a thick protective membrane is used for corrosion protection, then corrosion resistance is improved, but pressure sensing sensitivity deteriorates
Solution Approach 1:
A thin measuring membrane is used instead of a thick protective membrane because its flexibility and thinness allow it to deform easily under pressure variations, maintaining high sensing sensitivity. The membrane's thin structure ensures that even small pressure changes (on the order of one mbar) produce detectable deformations, while its material selection provides adequate corrosion resistance for the intended application environment.
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 device enables stable and sensitive detection of pressure variations in the order of one mbar, is compact, and cost-effective, while avoiding corrosion and explosion risks, with balanced and symmetrical signal stability for differential pressure sensing.
Implementation Method 1
a very thin corrosion-proof protective membrane which is slightly elastically deformable
Implementation Method 2
at least one Helmholtz-type resonator consisting of the association of a by-pass of the protective tube and of a cavity used as a resonating chamber
Implementation Method 3
at least one explosion-proof protective tube mounted downstream from the protective membrane in the direction in which the electric signals propagate, designed so as to avoid any flame propagation and used as a hydraulic resistance
Implementation Method 4
a deformation sensor sensitive to these mechanical deformations and capable of converting them into electric signals
Data Source
AI summary
A pressure sensing device particularly intended to equip a flowmeter of fluidic oscillator type, this device comprising a pressure orifice (3) linked to a measuring circuit (4) so as to send audible signals to a measuring membrane (1) fixed into a measuring cavity (2), a deformation sensor (5) sensitive to the deformations of this membrane and capable of converting them into electric signals, and an electronic amplifier associated with this deformation sensor (5), characterized in that the measuring circuit (4) comprises corrosion- and explosion-proof protection means (7, 8, 9) and filtering means (9, 10; 11, 12; 13, 2) for filtering the audible signals so as to enable the disturbance frequencies of these signals to be removed.