Today we want to discuss Gas Mixing. This has become a popular application for our clients. Bronkhorst is a market leader in Thermal Mass Flow Meters/Controllers and Electronic Pressure Controllers. Bronkhorst has vast experience in designing precise measurement and control devices. Our partnership with Bronkhorst is able to offer innovative solutions for many different applications for many different markets
Homogenous Gas Mixtures
We have noticed an increasing demand for special gas mixtures. Our Bronkhorst products are ideal for such applications. The process of gas mixing is more than just taking two different gas flows. There are many factors that have to be considered in the process. For instance, you may have to dilute the dopant with a certain dilution of gas. This is where an appropriate mixing chamber is used. Our partners at Bronkhorst have developed a series of special mixing chambers.
Application Note: Gas Mixing Setup To Calibrate Oxygen Sensor For Monitoring Beer Quality
Water, barley, hops and yeast are the main ingredients for making beer. In the process of brewing beer, air is used in fermentation for the reproduction of yeast cells. Almost all of the oxygen from the air is used in this step, so the steps that follow must use low amounts of oxygen to avoid oxidation. The taste and quality of the beer is dependent on the ability of avoiding oxidation.
Gases like Nitrogen (N2) and Carbon Dioxide (CO2) will be a part of the beer brewing process. With that in mind, calibrating sensors for oxygen level accuracy will have to factor in the influence of these other gases. Compositions of these gases have to be created and delivered to the oxygen sensor. These calibration tests run for weeks and characteristic curves are analyzed.
Bronkhorst delivered 6 Thermal Mass Flow Controllers as a part of 6 gas supply lines. The purpose of these controllers and supply lines was to mix these dry gases (Oxygen, Nitrogen, Carbon Dioxide, and Air) to create the intended formation. Each of the Mass Flow Controllers were calibrated with curves for Oxygen, Nitrogen, and Carbon Dioxide. These flow controllers were able to deliver accurate, low gas flows.
The Mass Flow Controllers are housed in stainless steel gas mixing boxes which also control operations via touch screen. Within the box, the controllers are grouped into 2 groups of 3 to ensure high accuracy. The gases move into the box and proceed to the 2 groups of Mass Flow Controllers and are then mixed together in the chamber. The Oxygen Sensor is mounted outside of the box and downstream from the Mixing Chamber.
This calibration setup can be programmed to generate 27 different gas consumptions. The Programmable Logic Controller (PLC) within the control box can be programmed so that the client can start the calibration using the first gas composition with just the push of a button.
We can customize this solution to fit your needs
- High accuracy
- Fast response, excellent repeatability
- Optional Multi-Fluid / Multi-Range functionality
- Virtually pressure and temperature independent
- Compact design
Gas Mixing Chambers
- Flow ranges from 300 mln/min up to 10.000 mln/min for creating homogeneous gas mixtures from percentages down to ppm-ranges
- Available with ¼” or 6 mm connections
- Pressure rating up to 20 bar