Efficient and accurate ozone production requires accurate measurements of gas flow rates. The rota-meter style flow-meter is a simple, robust, and accurate way to measure the flow of gas or liquid. The only moving part is a metal ball (float) within a tapered transparent tube. As flow rate increases, the ball rises. Try out this quick, one-question quiz to test your ability to read this instrument.
One limitation to this device is its inability to factor in gas pressure in a direct reading. Gas under pressure is squeezed together so more gas is able to flow past the ball than it reads. Some flow-meters are calibrated for a specific gas pressure. Such meters are accurate only at that pressure. This limitation is easily overcome with a simple calculation. You can calculate an accurate flow rate at any pressure when you know the gas pressure of the gas flowing through the meter. How did you do on the quiz? If you haven’t tried it yet, check out our calculator page for better chance of getting it right.
For liquids, various units are used depending upon the application and industry, but might include gallons (U.S. or imperial) per minute, liters per second, bushels per minute or, when describing river flows, cumecs (cubic meters per second) or acre-feet per day. In oceanography a common unit to measure volume transport (volume of water transported by a current for example) is a sverdrup (Sv) equivalent to 106 m3/s.