An Air Flow Meter is the flow meter that measures industrial air velocity. Most of the time, people talk about air flow meters means compressed air flow meters. We are discussing here all air flow meters, including compressed air flow meters. Depending on the type of application, the Air Flow Meter is made as a hot-wire, a vane, a cup anemometer, a Pitot tube flow meter. All air flow meters can measure air velocity as well as air pressure. The most common unit of measurement for air flow is m/s.

Featured Air Flow Meters

Air flow meters types

Carmen vortex air flow meter

The Carmen vortex refers to the placement of a cylindrical or triangular object in the fluid. Two rows of vortices with opposite rotation directions will be generated downstream of this object.

Optical Carmen Vortex Air Flowmeter

In the process of generating the Carmen vortex, the air pressure on both sides of the vortex generator will change. The pressure acts on the metal foil through the pilot hole, causing it to vibrate. When light from a light-emitting diode strikes a vibrating metal foil. The reflected light on the metal foil received by the phototransistor is vortex-modulated light. And its output is demodulated to obtain a frequency signal representing the air flow.

Ultrasonic Carmen Vortex Air Flowmeter

An ultrasonic transmitting probe and a receiving probe are oppositely installed on both sides of the downstream pipeline of the Carmen vortex generator. Due to the influence of the Carmen vortex on the air density, the time from the transmitting probe to the receiving probe of the ultrasonic wave becomes later than that of the non-vortex and a phase difference occurs. By processing this phase signal, a vortex pulse signal can be obtained.

Hot wire air flow meter works

When no air flows, the bridge is in equilibrium. The control circuit outputs a certain heating current to the hot wire resistance RH. When there is air flowing, the heat of RH is absorbed by the air and becomes cold. Its resistance value changes. The bridge loses Balance. If the temperature difference between the hot wire resistance and the intake air is kept constant and constant, the current IH flowing through the hot wire resistance must be increased. Therefore, the hot-wire current IH is a function of the mass air flow.

Hot film air flow meter

The working principle of the hot film type air flow meter is similar to that of the hot wire type air flow meter, and they all work with Wheatstone bridge. The difference is that the hot film type does not use platinum wire as a hot wire. But uses a thick film process to make the hot wire resistance, compensation resistance, and bridge resistance on the same ceramic substrate.

Vane type air flow meter

The vane type air flow meter has a simple structure and high reliability. Yet, it has a large volume, large intake resistance and slow response.

Mass Air Flow Meter

A thermal mass flow meter is a precision instrument. Thermal mass flow meter measures gas mass flow and is used in various industries. For direct mass measurement of industrial gases, compressed air, and aqueous fluids.The flowmeters indicate the mass flow or normalized volume flow of gases. Thermal mass flow meter measures without any additional pressure and temperature compensation.

Thermal mass flow meters have impressively high accuracy, short response time and a very wide flow range. With virtually no loss of accuracy even at the lowest flow rates. High turn down or low-pressure losses are important in gas metering applications. Thermal mass flowmeters offer a real alternative to traditional measuring techniques. Whether for process control, consumption and supply monitoring, detecting leaks or monitoring distribution networks.Using insertion versions, it is also possible to measure gas flows in very large pipelines or in rectangular ducts.

Applications of Thermal Mass Flow Meter

The thermal measuring principle is widespread in the industry, and is being used successfully in many applications with gas flow, for example:

  1. Compressed air (consumption, distribution)
  2. Carbon dioxide (for beverage production and chilling)
  3. Argon (in steel production)
  4. Nitrogen and oxygen (production)
  5. Natural gas (for burners and boiler feed control)
  6. Air and biogas measurement (e.g. in wastewater plants)

Ultrasonic Air Flow Meter

Ultrasonic flowmeters use sound waves to determine the velocity of a fluid flowing in a pipe. At no flow conditions, the frequencies of an ultrasonic wave transmitted into a pipe, and its reflections from the fluid are the same.Under flowing conditions, the frequency of the reflected wave is different due to the Doppler effect.When the fluid moves faster, the frequency shift increases linearly. The transmitter processes signals from the transmitted wave, and its reflections to determine the flow rate.Transit time ultrasonic flowmeters send and receive ultrasonic waves, between transducers in both the upstream and downstream directions in the pipe.At no flow conditions, it takes the same time to travel upstream and downstream between the transducers.Under flowing conditions, the upstream wave will travel slower and take more time than the (faster) downstream wave.When the fluid moves faster, the difference between the upstream and downstream times increases.The transmitter processes upstream and downstream times to determine the flow rate. They represent about 12% of all flowmeters sold.

Gases that can be measured with ultrasonic clamp-on flowmeters include:

Compressed AirHydrogenOxygen
NitrogenSteamNatural Gas
PropaneButaneCorrosive Gases
Erosive GasesHigh Purity GasesSterile Gases
Toxic GasesInert GasesCompressed Air

Inline Air Flow Meter (Vortex Flow Meter)

Vortex shedding flow meter, also called Vortex flow meter. Vortex shedding flow meter is suitable for measuring steam flow rate as well as liquids and gases. Vortex shedding flow meter, easy installation, low cost, analog and 4-20mA output. Pressure & temperature compensation can improve the sensor for more accurate measurement. Others flow meters can also measurement flow rate of liquids, like ultrasonic and turbine.

Air flow meter for compressed air

Compressed Air Flow Meter, is the digital flow meter work for the air compressor. Air consumption is an important info for industrial inline gas flow pipe. According to the measurement conditions, compressed air flow meter could be different types. Thermal mass flow meters, Ultrasonic flow meters, Vortex flow meters, Turbine flow meters. And the differential pressure flow meters (Orifice plate ) are also suitable for compressed air. With the Pressure and Temperature compensation. Sino-Inst’s compressed air flow meters are more affordable and complete.

Air flow meter price

The price of AIR flow meters are decided by flollowing factors:

  • Pipe diameter;
  • Flow range;
  • Measured medium;
  • Whether it is corrosive;
  • Whether explosion protection is required;
  • Whether it needs local display;
  • Connection method;
  • Measure pressure;
  • Measure temperature;
  • Signal output;
  • Accuracy requirements;
  • Material requirements;

Important factors when selecting flow metering devices are

  • accuracy
  • cost
  • legal constraints
  • flow rate range
  • head loss
  • operating requirements
  • maintenance
  • lifetime

These factors are more or less related to each other. Example – the cost of flow meters increases with accuracy and lifetime quality.

Sino-Instrument offers over 50 flow meter for flow measurement.

About 50% of these are differential pressure flow meters,

40% is the liquid flow sensor,

and 20% are Ultrasonic Level Transmitter and mass flow meter.

A wide variety of flow meters options are available to you,

such as free samples, paid samples.

Sino-Instrument is a globally recognized supplier and manufacturer of flow measurement instrumentation, located in China.

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