Working with Gill Technology, we have produced a number of custom MAF Sensor and gas-flow sensor products which use ultrasonic technology to determine the rate of flow. Each system has a pair of ultrasonic transducers and conditioning electronics that are used to measure the time taken for a pulse of ultrasound to travel between the transducer pair. A measurement is taken in both directions and the difference in time of flight is then used to calculate the flow velocity. If there is no gas flow then the time measured in each direction will be the same and no velocity will be measured. If a gas flow is present then the down stream ultrasonic pulse will get there quicker than the upstream ultrasonic pulse and hence a velocity can be computed.
If you have a custom gas-flow sensor requirement please visit the Gill Technology website to view our examples of MAF sensors and Microflow Meters and how we will work with you to get your product to market.