Can Magflow Flow Meter Measure Gases?

A magflow flow meter indeed cannot be used to measure the flow rate of gases. The main reasons are as follows:

1. Conductivity difference:

The operating principle of an electromagnetic flow meter is based on Faraday’s law of electromagnetic induction, which requires the measured medium to have a minimum level of electrical conductivity. Most gases have extremely low conductivity, making it impossible to generate enough induced voltage for the magflow flow meter to function properly.

2. Unstable flow conditions:

Gas flow in pipelines tends to be much more unstable than liquid flow, often producing vortices and turbulence. These irregularities can cause significant measurement errors in magflow flow meter.

3. Density difference:

Gases have much lower density than liquids, which means that under the same volumetric flow conditions, gas velocity is usually much higher. This affects the calibration and configuration of the magflow flow meter, reducing measurement accuracy.

4. Pressure influence:

Gas flow characteristics are highly pressure-dependent — variations in pressure can cause changes in gas density and velocity. This makes it difficult for a magflow flow meter to maintain accurate measurements across different pressure conditions.

5. Magnetic field interaction:

Unlike liquids, gases are not conductive enough to interact with the magnetic field in a measurable way. As a result, no measurable voltage is induced in the flow, which is another fundamental reason why magflow flow meter cannot measure gas flow.

Core Reasons Why Gases Cannot Be Measured by a Magflow Flow Meter

Reason 1: Gases lack sufficient electrical conductivity

An magflow flow meter requires the measured medium to have a minimum electrical conductivity, typically above 5 μS/cm (depending on the manufacturer). However:

Common industrial gases such as air, nitrogen, oxygen, and carbon dioxide are essentially insulators with conductivity close to zero.

Even gases containing small amounts of water vapor or impurities still have conductivity far below the required threshold.

As a result, when gas flows through an electromagnetic flow meter, no measurable induced voltage is generated between the electrodes, and the instrument cannot produce a valid reading.

Reason 2: Low gas density leads to extremely weak induced signals

Even when attempting to measure certain ionized gases or plasma, the signal remains very weak because:

The density of gas is much lower than that of liquids, causing greater velocity fluctuations and turbulence.

Electromagnetic flow meters rely on a high signal-to-noise ratio, and such weak signals are easily drowned out by background noise.

Reason 3: Lack of effective contact interface within the gas medium

Magflow flow meter require both electrodes to be in direct contact with a uniform, conductive liquid. However:

Gases are highly compressible and tend to form bubbles, voids, or intermittent flow within the pipeline.

This makes it impossible to maintain a stable electrical contact layer on the electrode surface, resulting in frequent signal interruptions or severe fluctuations.

Therefore, in practical applications, other types of flow meters are recommended for most gas flow measurement scenarios. For example, a vortex flow meter measures flow based on the vortex-shedding effect generated as the gas passes a bluff body, making it suitable for both gases and liquids. A thermal gas mass flow meter, on the other hand, measures gas flow by detecting the heat transfer effect caused by the gas flowing over a heated element, offering high measurement accuracy and stability.