Mass Flow Meters: What is It and How Does It Work?

Mass Flow Meters: What is It and How Does It Work?

Mass Flow Meters: What is It and How Does It Work?

Introduction

Before, the mass flow was usually or normally computed from the outputs of a densitometer and a volumetric flow meter. Also, density was either calculated or directly measured using the outputs of pressure transmitters and process temperatures.

These measuring devices were not extremely precise or error-free, due to the relationship between the temperature or process pressure and density aren’t, for the most part, accurately known. Every sensor put on another error to the overall error measurement.

Also, the response speed of such computations is typically insufficient to notice or perceive step changes in the flow. For a little help, we will walk you through the important things to know about a mass flow meter. Read on!

How Does It work?

This flow measuring technology functions either by keeping a probe at an unvarying temperature and calculating the power to do so or by presenting a definite amount of heat into the stream and calculating a related temperature change. There are basically two mass flow meter configurations, namely, straight tube flow meter and curved tube flow meter.

Moreover, mass flow meters operate on the inertia principle made by the fluid passing through an oscillating tube. It makes the tube to move in proportion to the mass flow rate. Most mass flow meters have, for the most part, two tubes. They’re made to shake in opposition to each other through a magnetic coil.

Coil sensors and magnet sensors are installed in the outlet and inlet of both tubes. So, as the coils traverse through the electromagnetic field created by the magnet, they produce or generate voltage through a sine wave. These waves are the means to measure the mass flow.

When fluid is not flowing through the tubes, the outlet and inlet sine waves are in sync. However, under flowing conditions, the tubes move in corresponding to the mass flow rate. The amount of movement is determined by the outlet sensors and inlet sensors, based on a time difference that happens in the waves created by the two sensors. The flow rate is calculated from the difference of the sine waves created by the outlet and inlet sensors.

Phase shift between the inlet and outlet sine waves

Phase shift between the inlet and outlet sine waves

Mass Flow Meter Applications

Mass flow meters are, for the most part, utilized in controlling or monitoring mass-related processes, for example, chemical reactions that rely on the unreacted ingredients’ relative masses. For instance, custody transfer operations, billing operations, material balance determinations, and recipe formulations.

Since these are most important or quintessential flow measurements in an industrial process plant, the accuracy and reliability of mass flow measurement are undoubtedly critical. In determining or knowing the mass flow of compressible gases and vapors, the flow measurement is not affected by the changes in temperature or pressure.

One of the best things of this measuring device is that it can precisely calculate low gas velocities or low gas flow rates (at least 25 feet per minute). It is much lower compared to what you can detect with other flow measuring devices.

Mass flow meters offer towering rangeability (10:1 to 100:1), particularly if they’re utilized in constant temperature difference mode. Moreover, when the heat is unchanging, the capability to perceive small temp differences is restricted, and both rangeability and precision drop off.

Under normal flow conditions, errors in measurements are typically in the one or two percent full-scale range. Mass flow meters are available in high temperature and high-pressure designs. Plus, in materials such as PFA, Monel, and glass.

Probe-type designs and bypass can perceive large flows in dryers, flare stacks, and ducts. On the other hand, flow-through designs are utilized to calculate or compute small flows of clean substances.

Limitations

Although mass flow meters can have reasonable accuracy and high rangeability, it can have several limitations. Possible issues include the buildup of moisture on the temp detector. This problem will make the thermometer to give an unreliable and inaccurate reading, plus, it can lead to damage due to corrosion.

Material or coating buildup on the temperature sensor will cause the device to read low and impede heat transfer. Moreover, additional problems include changes in the particular heat because of the variations in the composition of the gas.

Some common applications for mass flow meters include the filter and leak testing, gas chromatography, research applications, chemical industries, air sampling, and combustion air measurement.

Takeaway

Keep in mind that calculating the mass flow rate is very important. It is critical, especially when you are dealing with or working on a process where you need to look for the mass flow. For instance, batching, you must know how many grams or grams per minute; thus, batching relates to the mass. In most processes, it is essential to determine the correct fluid, and some applications need the capability to get precise flow measurements to make certain that a product is of high-quality.

 

Author’s Bio:

Sylvia Hopkins is a writer and a blogger who specializes in email marketing campaigns and ghost blogging. She writes about flow measurement instrumentation, flow measurement application, and technology. When not working, Sylvia spends some quality time with her family and friends.

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