Schematic depicts sound-wave transmitter and receiver (microphone) placed at opposite ends of a gas-filled chamber.
Credit: S. Kelley/NIST
Researchers at NIST have developed a new — and sound — way to accurately measure the rate at which gas flows in and out of a vessel. The technique, which uses acoustic waves to determine the average temperature of the gas and microwaves to ascertain the volume of the vessel, can measure gas flows and leaks from large containers particularly well.
The method could enable workers to more accurately calibrate gas flow meters used in natural gas pipelines. The monetary value of natural gas in U.S. pipelines exceeded $90 billion in 2016, so the accuracy of these measurements is a key concern for both consumers and providers of natural gas.
“We believe that the acoustic technique, once perfected, could be adopted as a new standard at NIST, and potentially around the world,” said NIST researcher Jodie Pope.
Measuring Gas Temperature with Sound
In a new method for measuring gas flow, NIST researchers tracked the changing temperature of a gas using sound waves. A speaker placed at one end of a gas-filled chamber sends sound waves through the gas to form a standing wave, or resonant, wave, detected by the microphone. As gas exits the vessel, the remaining gas cools down, which is detected by a shift in the resonance frequency of the sound waves. Credit: S. Kelley/NIST
To determine the amount of gas flowing out of a vessel, researchers need to know several quantities, including the volume of the vessel and the pressure and temperature of the gas.
In the current method of measuring gas flow, developed at NIST and now sounding measure
