Air Flow Meters
Air flow meters are devices used to measure various aspects of the flow
of air. Air flow meters may measure the volume of the air, the speed of
the air or the mass of the air, depending on the type. Air flow meters
are most frequently used to infer mass flow after taking various flow
measurements such as absolute pressure, differential pressure, viscosity
and temperature as air flows through a tube. Besides air, these flow
meters can also measure many different types of gases including
nitrogen, oxygen, argon, helium, hydrogen, natural gas and carbon
dioxide.
Air flowmeters have many plastic
or metal parts that work together to produce a reading. The parts are
manufactured to very close tolerances in order to provide readings with an
accuracy as low as 2%. Air flow meters come in several types. Besides
variations such as size or material, they may vary in pressure range, switching
technology, and the presence and type of transmitters. These variations allow
air flow meters to have applications in several industries. In the medical
industry, flow meters are used to measure patients' air intake, allowing
physicians to further determine the severity of any illness. These types of
flow meters are called peak flow meters and are particularly beneficial for
asthma patients. Air flow meters are also common in the automotive, petroleum
and gas, utility services, HVAC, food processing and raw materials industries.
There are four main categories of air flow meters that are
identified based on how they obtain a reading of the flow rate or quantity of
air. Differential pressure air flow meters
are the most common type. These devices take both a primary and a secondary
measurement and report the difference. The first measurement causes a change in
kinetic energy by directing the air through a hole or orifice in the flow meter
which is measured by the second element. Positive displacement meters separate
the air flow into specific volumes which are then counted. Vanes, gears,
pistons, or diaphragms are commonly used to divide the air which is counted
mechanically or electronically. Velocity air flow meters use a depth
measurement and the average air velocity of the flow to produce a reading. They
have a greater range than differential pressure devices. The last category is
true mass air flow meters. They directly measure the mass of the fluid, not the
volume; two common kinds are thermal meters and Coriolis flow meters. Air flow
meters vary in how they obtain and report a reading but the list of parts may
include pressure ports, bellows, spindles, pinions, gear mechanisms, gauges,
cell caps, magnets, sensors, pistons, nuts, seals, levers and more.
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Air Flow Meters - Sierra Instruments |
Air Flow Meters - Sierra Instruments |