Being able to measure ducted airflow cheaply and non-intrusively, like with this ultrasonic flow meter, could be a big deal for DIY projects and the trades in general. The principle behind the ...

Utilities can improve water, gas and heating metering accuracy by an order of magnitude, while operating for up to 20 years on an “A”- size battery with Maxim’s MAXREFDES70# ultrasonic flow meter ...