Vane anemometers are also available. Vane anemometers are usually larger than a hot wire but are more rugged and economical. Models are available with temperature and humidity measurement. Mass or Volumetric Flow Rate? So you want to measure flow? The answer would seem to be to purchase a flowmeter. With fluid flow defined as the amount of fluid that travels past a given location, this would seem to be straightforward — any flowmeter would suffice.
However, consider the following equation describing the flow of a fluid in a pipe. Putting this equation into action, the flow of a fluid traveling at an average velocity of a 1 meter per second through a pipe with a 1 square meter cross-sectional area is 1 cubic meter per second. Putting this equation into action, the flow rate will be 1 kilogram per second when 1 cubic meter per second of a fluid with a density of 1 kilogram per cubic meter is flowing. Without getting into details — a pound is assumed to be a mass unit.
Now — which flow do you want to measure? Not sure? In some applications, measuring the volumetric flow is the thing to do.
Consider filling a tank. Volumetric flow may be of interest to avoid overflowing a tank where liquids of differing densities can be added. Consider controlling fluid flow into a process that can only accept a limited volume per unit time.
Volumetric flow measurement would seem applicable. In other processes, mass flow is important. Consider chemical reactions where it is desirable to react substances A, B and C. Of interest is the number of molecules present its mass , not its volume. Similarly, when buying and selling products custody transfer the mass is important, not its volume. How much maintenance does a flowmeter require? A number of factors influence maintenance requirements and the life expectancy of flowmeters.
The major factor, of course, is matching the right instrument to the particular application. Poorly selected devices invariably will cause problems at an early date. Flowmeters with no moving parts usually will require less attention than units with moving parts.
But all flowmeters eventually require some kind of maintenance. What is a Flow Meter? If your are interested to learn more about flow-rate and fluid dynamics, watch this lecture:. The store will not work correctly in the case when cookies are disabled. Replacement Filters by Size 2. How to Measure Your Flow Rate. Helping you find the right sized system In order to serve as a rough guide for choosing your water filter and treatment system, the table below shows average flow rates in Litres per Minute LPM.
How to find out the flow rate of your water In order to buy the correct Ultra Violet UV system, it is important to have an approximate estimate of your water flow rate. Divide 5 by the time it took to get the number of gallons per unit time. If you measure time in minutes, you'll get the result in gallons per minute. To measure flow rate from a small orifice, such as that of a drip emitter, you'll need a much smaller container, such as a quart jar, and a longer unit of time, but the principle is the same.
Drip emitters are usually rated in the number of gallons per hour they emit. An emitter that puts out 1 gallon per hour will fill a quart jar in 15 minutes. If the fluid is flowing through an orifice or a clear tube, one way to measure velocity is to introduce dye as a marker and time how long it takes the dye to pass two points.
For flow through natural features, such as a riverbed, you have to approximate the area. Assume the deepest part of the river to be the radius of a semi-cylindrical trough. Analyst 6 — CrossRef Google Scholar. Ayliffe HE, Rabbitt RD An electric impedance based microelectromechanical system flow sensor for ionic solutions.
Collins J, Lee AP Microfluidic flow transducer based on the measurement of electrical admittance. Wu J, Ye J Micro flow sensor based on two closely spaced amperometric sensors. Lien V, Vollmer F Microfluidic flow rate detection based on integrated optical fiber cantilever. John Collins 1 Email author Abraham P.
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