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The Difference Between Thermal Mass Flow Meters & Laminar Flow Meters

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Mass Flow Meters monitor the flow of a liquid or gas moving through a system, measuring the mass per unit of time. This metric is critical for recipe formulations, determining material balancing, and other applications. However, different configurations of Mass Flow Meters are available, and evaluating which is best for your operations can be challenging.

Two common options are Thermal Mass and Laminar Mass Flow Meters.

What is a Thermal Mass Flow Meter?

A Thermal Mass Flow Meter, sometimes called a thermal flow sensor, is a device used to measure air flow on a molecular level to provide accurate, dependable, and repeatable gas flow values. Unlike other flow meters or sensors, Thermal Mass Flow Meters are not impacted by changes in the temperature or pressure of incoming air. As gas or liquids move through the flow meter, the device introduces heat into the flowing stream and then measures the temperature change to establish the required volumetric measurement.

Thermal Mass Flow Meters are typically constructed from a stainless steel wetted path to resist corrosion and chemical damage during delicate operations. Other materials, such as ceramic Kynar®, are also available.

Thermal Mass Flow Meter Applications

Thermal Mass Flow Meters and sensors are ideal for low-flow applications, particularly those under 6000 SCCM:

Advantages & Disadvantages of Thermal Mass Flow Meters

Thermal Mass Flow Meter advantages include high levels of repeatability, accuracy, and customizability. They are easily accessible, cost-effective, and work in extreme environments involving pressure or temperature fluctuations. Thermal Mass Flow Meters can even work in areas labeled as hazardous.

However, they are not a catch-all solution for every flow meter need. Thermal Mass Flow Meters can be compromised if condensation occurs on the temperature detector, throwing off the readings. Other buildups on the sensor can also block heat transfer and compromise the accuracy of the overall measurements.

What is a Laminar Flow Meter?

A Laminar Flow Meter, also called a laminar flow sensor, is a device with a linear relationship between differential pressure and volumetric flow rate. When in laminar flow, flow streams show no turbulence with limited mixing between adjacent molecules. Generally, a Laminar Flow Meter will be used within a system made from one or more tubes with lengths that greatly exceed the internal diameter, producing slow-moving flow velocity.

Most Laminar Flow Meter wetted paths are constructed from stainless steel to withstand harsh conditions or maintain hygienic environments.

Applications for Laminar Flow Meters

Laminar Flow Meter applications usually require tight or specific tolerances and involve flows above 6000 SCCM. Examples include:

  • Pneumatic tools, systems, or controllers
  • General industrial applications utilizing gas flow
  • Industrial dispensing jobs
  • And more!

Laminar Flow Meter Advantages & Disadvantages

One benefit of a Laminar Flow Meter is its ability to form a linear relationship between flow rate and developed pressure drops. Another benefit is that it can monitor high-viscosity liquids while providing low-noise operations. While they do tend to cost more upfront, Laminar Flow Meters provide more control and precision during use.

There are some disadvantages. Unlike Thermal Mass Flow Meters, Laminar Flow Meters will be impacted by temperature fluctuations and particularly harsh environments, making them better suited to more consistent manufacturing lines. Certain configurations will even require a temperature control system to operate at optimum levels.

Zaxis Can Help Identify the Best Flow Meter for Your Application

Please contact Zaxis today to determine which metering pump or sensor is best for your specific operations. Our expert team has decades of combined industry experience and will find the right leak testing or dispensing solution.

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