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How to perform Gas Sampling using Digital Mass Flow Meter?

Gas Sampling using Digital Mass Flow Meter

How to perform Gas Sampling using Digital Mass Flow Meter

The Vögtlin red-y compact 2 meter is used as the heart of a reliable automatic in the analytical world, low-cost gas sample taking the device. Emission or environment measurements often demand periodic sampling of a fixed amount of gas and collect these in a container or sample bag.

For example every hour a 100 scc sample. The red-y compact 2 meter with its optional smart alarm module has the complete solution without the need of any PLC to control the process.

Figure 1

Vogtlin Gas Flow Sampling with Mass Flow Meters

Figure 1 shows a very simplified diaphragm and the system runs on 24 Vdc. Totalizer, the high and low alarm can individually programmable for different alarm functions via the Red-y compact two-alarm module that has three alarm points. The capability to reset the alarms and totalizer and the timer function also utilized with an I/O input on the alarm module.

Program the Alarm 1 as a totalizer alarm with the sample requires a volume to collect in each sample. This example is 100 SCC (Standard cubic centimeter).

Duration of the alarm between 100msec and 2.78 hours programmed in that alarm function, this time sets the time between the samples. Once the process starts, the solenoid will open and a pre-set amount of gas will flow into the sample bag or container. One the defined amount is reached, the Alarm 1 will open and close the solenoid, and the gas flow will stop. Because of the programmed Alarm, 1 duration setting the alarm will stay active for the pre-programmed time, in our example 1 hour.

Once this hour is over, Alarm 1 is programmed to reset itself automatically, and the counter goes back to zero. The solenoid is activated again, the gas will flow, and the totalizer repeat until the pre-programmed value is reached, the process starts all over again. The process will continue, and every hour one sample of 100 SCC will flow into the sample container.

Diagnostics set in Alarm 3. The alarm will sound if:

  • The sample bag/container gets full
  • Water enters the sample line
  • The flow during sampling is too low (blockage of sample line)
  • The flow is too high (Too high pressure in the process)

In this case, push the reset button to deactivate the alarm and continue the process. There are many other variations possible. Every system is a bit different, you can find additions like purging, filtering, pressure reduction, gas drying, etc. out in the field.
Many of the users of these systems obtain a battery powered high accuracy red-y compact 2 meters to verify if the flow meter in the field is working correctly or if it needs calibration or cleaning. The red-y compact 2 has a significant internal diameter flow channel, has a low-pressure drop, is temperature compensated and measures the mass flow, independent of changes in pressure and temperature.

Flexibility

It is impossible to describe all process in which these type of flow meters are used, but if you see a VA meter for gas and you want to improve a process, talk to the experienced Vögtlin engineers and they will be pleased to help you to find a solution.

Conclusion

Customer around the globe makes use of the advantages in the analytical field, in research and development, in light industrial applications, in semiconductor segments and other forms. Very often we hear from the users “The beauty of the Vögtlin Thermal Mass flow instruments is once you install, set then forget them, as they work so reliable and independently.”
Vögtlin’s worldwide network of distribution and sales partners will help you select most correct equipment that matches specific needs and best for your application.

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Variable Area Flow Meter or Mass Flow Meter for Gas Flow Measurements

Variable Area vs Mass Flow
Vogtlin Q Flow - Variable Area Flowmeter
Red-y Compact Meter Mass Flow Meter

Comparison between Variable Area Flow Meter and Mass Flow Meter often compare of Volumetric Flow and Mass Flow Measurements.

What good of Mass Flow Over Volumetric Flow Measurements

  • Mass Flow Meter is having widest Turndown Ratio, Fast Response Time, High Accuracy and also High Repeatability.
  • Mass Flow Rate independence to pressure and temperature changes.
  • Pressure and temperature compensation does not require direct mass flow measurement hence improve the cost-effectiveness of gas flow measurement.

VA-Flow Meter v.s. Mass Flow Meter

Industrial flow measurements applications often require a higher accuracy together with pressure and temperature compensation which not possible to achieved with conventional Variable Area Flow Meters.

Hence Variable Area Flow Meters are extremely sensitive to pressure and temperature changes. 1 Bar pressure changes in process can generate an error of 50% in gas flow measurements. Therefore the flow compensation of Mass Flow Meters creates repeatability.

Common Variable Area Flow Meter in flow measurement possible only with Vertical Installation, however, smart Digital Mass Flow Meters provide installations flexibility both horizontally and vertically. In the past the Variable Area Flow Meters having great advantages of no power supply required, however with innovation, now Mass Flow Meter with AA Battery Powered available without compromise of measurement accuracy.