MASS-STREAM™ Thermal Mass Flow Technology

October 10, 2017 Chris King

For over 35 years Bronkhorst High-Tech has brought a revolutionary flow technology to the market, and in today’s blog I would like to discuss one such example, called MASS-STREAM™. This device leverages Constant Temperature Anemometer (CTA) thermal mass flow technology, though differently than conventional meters in this category. I will describe what CTA thermal mass flow meters are, the conventional type and their applications, and what makes MASS-STREAM™ technology different.

What is a conventional Constant Temperature Anemometer (CTA) thermal mass flow meter?

The constant temperature anemometer (CTA) thermal mass flow meter works with a sensor with probes, which are inserted into the gas stream in order to directly contact the flowing gas. One of the two sensors is designed as a heater, and the other one is designed as a temperature probe.

When the instrument is powered up a constant difference in temperature (ΔT) is created between the two sensor probes. The heater energy required to maintain this ΔT is dependent on the mass flow. The working principle is based on King’s Law of the ratio between the mass flow and heater energy. What that means is the higher the flow, the more energy is required to maintain the chosen.

A conventional CTA thermal mass flow meter is installed by inserting the long probes through the pipe wall and into the gas stream. The probes are passed through an insertion port (hole) in the pipe. The “head” of the instrument is above the outer wall of the pipe.
Common characteristics of CTA thermal mass flow meters are having no moving parts, a low pressure drop across the instrument, and no need for additional temperature or pressure compensation.

Where are conventional Constant Temperature Anemometer (CTA) thermal mass flow meters used?

As you might imagine, processes where gas flows in pipes are places one will find CTA thermal mass flow meters. The rugged nature, no moving parts, and low pressure drop are beneficial for measuring gas flow in industries like midstream Oil & Gas, upstream Oil & Gas, Wastewater treatment, and Steel.
The types of applications where these flow meters are used include applications with gases such as methane, propane, argon, compressed air, coal emissions, carbon dioxide, ammonia, and others as well.

Typically a CTA thermal mass flow meter is a good choice when the gas has the potential to be dirty or includes some moisture as the through flow nature of the technology can be more forgiving to contamination than other flow meter technologies.

CTA measurement principle
CTA measurement principle

MASS-STREAM™ Mass Flow Meters

Also based on CTA thermal mass flow technology, the MASS-STREAM™ flow meter/controller differentiates itself from conventional CTA flow meters on several points:

1. In-Line

The MASS-STREAM™ flow meter/controller is not installed using an insertion port through the wall of a pipe. Rather, the MASS-STREAM™ is an in-line flow instrument. That means that the instrument itself is connected between two ends of the tube or small pipe and effectively becomes part of it.

Unlike the conventional CTA thermal mass flow meter, the MASS-STREAM™ is a compact instrument where the main circuit board housing and sensor sit on top of the flow body through which the sensor probes project. An inline instrument allows for the use of CTA technology in applications using tubes and small pipes.

2. Flow Rate

As mentioned earlier the MASS-STREAM™ flow meter/controller is an instrument which is mounted in the line of the tube or small pipe, and applications which use tubes for flowing gas are ones where the flow rate is low.
Of course “low” is a subjective term, so as an example the MASS-STREAM™ lowest flow range is 10 -200 mln/min, but the flow meter family can go as high as 5000 ln/min.

3. Control

Perhaps the most important difference between the MASS-STREAM™ and the conventional CTA thermal mass flow technology is that the MASS-STREAM™ is available as a meter (as are all the others) or as a thermal mass flow controller.

The MASS-STREAM™ thermal mass flow controller is a complete control loop. It measures the gas flow, it has an onboard PID algorithm, and it provides a control signal to an electrically and mechanically connected control valve. All it needs is a setpoint signal and it will precisely control of the gas flow.
It is a complete control loop that can easily fit in one’s hand.


In conclusion

While other CTA thermal mass flow meters well serve the applications for which they are best suited, none are designed for low flows or as a complete control loop like the MASS-STREAM™. This meter serves applications ranging from process industries to food and beverage to pharmaceuticals to medical and chemical and beyond. MASS-STREAM™ technology is usable for virtually any kind of gas or gas mix, provides precise control, and is very compact and robust.

In our blog ‘How mass flow meters can help hospitals save on medical gases’ an application of MASS-STREAM technology used in the medical industry has been explained.

Check our video of the principle of operation of MASS-STREAM instruments.

To learn more about MASS-STREAM™, and whether it’s the right meter for your application, please contact our office.

Have a look at our video about the MASS-STREAM Thermal Mass Flow Controller

Bronkhorst High-Tech B.V.

Nijverheidsstraat 1A
NL-7261 AK Ruurlo (NL)
Tel. +31 573 45 88 00

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