Fiber-Optic Paddle Wheel Flowmeter for Hazardous Gas Flow Sensing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing flowmeters for measuring air flow in hazardous environments, such as robotic painting booths, rely on electronic differential pressure sensors that require electrical power, leading to high costs, reduced lifespan due to wear, and carbon buildup, posing safety and approval challenges.
Innovation Solution
A flowmeter system using a paddle wheel that interrupts a light beam to measure air flow, positioned within a non-hazardous environment, converting pulsed light signals to rotational speed for accurate flow rate measurement without electrical components in the hazardous zone.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If electronic differential pressure sensors are used to measure flow rate in hazardous environments, then flow measurement capability is provided, but electrical power is required which increases cost and creates safety approval challenges
Solution Approach 1:
The patent replaces electronic differential pressure sensors with a mechanical paddle wheel flowmeter that uses optical detection. The paddle wheel rotates in response to gas flow, and this mechanical rotation is detected by an optical sensor (LED and photodetector) that does not require electrical power in the hazardous environment, thereby eliminating the need for electrical approvals while maintaining flow measurement capability
Solution Approach 2:
The patent introduces optical fibers as an intermediary to transmit the light signal from the hazardous environment to the external electronics. The optical detector and signal processing electronics are located outside the hazardous zone, allowing flow measurement without introducing electrical components into the explosive atmosphere
2Measurement precision
If electronic pressure sensors with electrical contacts are used, then flow measurement is achieved, but sensor lifespan is reduced due to contact wear and carbon buildup
Solution Approach 1:
The patent eliminates electrical contacts entirely by using a non-contact optical detection system. The LED and photodetector detect the rotation of the paddle wheel through optical means without any physical or electrical contact, thereby eliminating wear and carbon buildup issues that plague electronic pressure sensors with sliding contacts
Solution Approach 2:
The optical detection system requires no maintenance or servicing. The LED and photodetector continue to function without degradation from contact wear, and the system automatically continues to measure flow without requiring replacement or cleaning that would be necessary for electronic sensors with electrical contacts
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
Provides accurate air flow measurement in hazardous environments without the need for electrical power, eliminating sensor wear and carbon buildup, thus reducing costs and ensuring compliance with safety regulations.
Implementation Method 1
A light beam is provided on an optical input cable that crosses the recess and is received by an optical output cable. The light beam is intermittently interrupted by the paddle wheel as the paddle wheel rotates so that the light beam on the optical output cable is a pulsed light beam.
Implementation Method 2
The processing electronics also includes an optical source that provides a light beam on the optical input cable
Implementation Method 3
The processing electronics includes a light detector that receives the light beam from the optical output cable
Data Source
AI summary
A flowmeter system including a flowmeter having a body defining a flow channel and a recess. A paddle wheel is positioned in the recess and is rotatable in response to gas flow through the channel. An optical source provides a light beam on an input cable that crosses the recess and is received by an output cable. A light detector receives the light beam from the output cable. The light beam is intermittently interrupted by the paddle wheel as the paddle wheel rotates so that the light beam on the output cable is a pulsed light beam. Processing electronics converts the pulsed light beam to a rotational speed of the paddle wheel that is then converted to a gas flow rate through the flow channel. The flowmeter is positioned in the hazardous environment of a painting robot and the processing electronics is positioned outside of the hazardous environment.