Gas flow meter makes sampling simple

“Truly Swiss, truly flexible”

Gas sampling is the first step in the collection of data that guards our process variables, monitors your emissions and verifies that your processes are running consistently. We see more and more demand for regular interval sampling that needs to be consistent and reliable. Sample specialists have discovered the simplicity and economics of the Vögtlin red-y compact Mass flow meter with optional integrated alarm module.

Developed in Switzerland this extraordinary gas measurement instrument offers true portability due to its long life on a single AA battery. All 50+ variables can be adjusted through a built-in touch screen. No need to connect the unit to a computer unless you want to update the firmware or power the unit through its USB connection.

Available for all kind of gases, in ranges from 0-10 sccm up to 0-480 slpm (air equivalent), the compact 2 fits a lot of applications. Sometimes this “fit” is in the small but many details, for instance OEM users appreciate that if you turn the unit around, the display automatically adjusts its position for the viewer. Important if the flow does not go from left to right. Overall users appreciate the economics, the quality and reliability of this device.
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Figure 1: red-y compact 2 with manual control valve

​Traveling engineers use this portable battery powered unit in adjusting gas flow settings, leak testing and verifying other flow meters. Once the battery reaches its life end, it can easily be replaced as AA batteries are basically just available everywhere. As an alternative, the unit can be powered through the USB cable by a power bank or a USB-port on your laptop or PC computer.

In the following application, users make use of the alarm module expansion that gives them 3 alarm points, 2 I/O inputs and an external power supply. The alarm module replaces the battery compartment and is integrated in the compact 2 at the back with a 3 meter 12 conduct wire for all the connections.
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In the analytical world the red-y compact 2 is used as the heart of a reliable automatic, low cost gas sample taking device.

Emission or environment measurements often demand periodic samples of a fixed amount of gas and collect these in a container or sample bag. For example every hour a 100 scc sample. The compact 2 with its optional smart alarm module has the complete solution without the need of any PLC to control the process. The system runs on 24 Vdc and a very simplified diagram can be seen in figure 3. The Vögtlin compact 2 alarm module has 3 alarm points that are individually programmable for different alarm functions, such as totalizer, window, high and low alarm. We will also make use of the timer functions and the ability to reset the alarms and totalizer with an I/O input on the alarm module.

We program Alarm 1 as a totalizer alarm with the sample volume we want to collect in each sample, in our example 100 scc (Standard cubic centimetre).

In that alarm function we can also program a duration  of the alarm between 100 msec and 2.78 hours. 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 automatically reset itself, the counter goes back to zero. The solenoid is activated again, the gas will flow and the totalizer start counting again till 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.

​Alarm 3 is used as a diagnostics. The alarm will sound if: 1) The sample bag/container gets full 2) Water enters the sample line 3) The flow during sampling is too low (blockage of sample line) 4) The flow is too high (Pressure in process too high) In this case you have to 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. In figure 4 you find a simplified diagram that serves as an example.

Many of the users of these systems obtain a battery powered high accuracy compact 2 to verify if the flow meter in the field is working properly or if it needs calibration or cleaning. The red-y compact 2 has a big 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. Below 2 more applications from users.

Simple gas mixing applications
The compact 2 is available as a meter or with a built-in easy to fine adjust positive shut-off needle valve. Several customers switched to a compact 2 with needle valve as an alternative to a VA meter. VA meters have several advantages, but main “con” is that they are very sensitive to changes in pressure and temperature of the gas. 14 Psi or 100 kPa pressure change may create an error of 50% in the reading and for many application this is not acceptable.

The red-y compact 2 does not have these problems. It measures the mass and is independent of pressure and temperature, which means that even if your process gas temperature or pressure changes the instrument still gives an accurate flow value.
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Figure 5: Manual gas mixing system

So if you want to build a simple low cost, but accurate gas mixer, the compact 2 is the ideal instrument. With its
single AA battery operation it is also convenient in the field. You can program up to 3 gases in every unit.

Consumption monitoring
The compact 2 has two (2) built-in totalizers and the menu can be protected with a password. This make the unit very suitable for consumption measurements. With the 100:1 turndown, it can measure both the small and the big flows used in your departments. Customer specific turndown ratios higher than 100:1 can be realized to obtain an indication of very low consumptions.

Monitoring is more than assigning costs to different applications, it is also safety and economics. By monitoring your gas usage you detect leaks and solve the problems before they cost you a lot of money or even more important create an explosive atmosphere in your laboratory.

Conclusion
These are just 3 of the many and extensive possibilities of the red-y compact 2 by Vögtlin. Customer around the globe make use of its advantages in the analytical field, in research and development, in light industrial applications, in semiconductor segments and other applications.

Very often we hear from the users “The beauty about the Vögtlin Thermal Mass flow instruments is that you install, set and forget them, as they work so reliable.” Vögtlin’s world-wide network of distribution and sales partners will help you selecting the equipment that matches best for your application and specific needs. Local service centres in the USA, China and Europe provide the aftersales support. Find out more about the red-y compact 2, the company and their other products on our website.

Figure 3 electrical diagram periodic gas sampling system

Figure 4 wiring diagram periodic gas sample system

Figure 6: Gas consumption monitoring on USB, AA Battery or 24 Vdc