Think of an NDIR CO2 sensor as a detective — a wily detective to be exact. Like a real-life detective that uncovers mysteries to help you solve a crime, the nondispersive sensor reveals the secret of the air around you, specifically its carbon dioxide content. Given that, it’s no surprise the device is an indispensable tool in the food industry.
At the heart of a Non-Dispersive Infrared (NDIR), of course, is infrared. Take note that carbon dioxide (CO2) is unique among gases as it can absorb infrared energy. Thus, by looking at how extensive infrared light is absorbed and re-emitted in a specific wavelength, we can determine the levels of carbon dioxide in a particular environment.
These days, carbon dioxide may have earned a bad reputation. With its ability to absorb long-wavelength infrared energy (heat) from the planet and re-radiate it downward, CO2 has become notorious as an effective heat-trapping greenhouse gas. Small wonder some environmentalists call it evil incarnate.
But that’s just one side of the story. Let’s not forget plants need carbon dioxide to produce food. More importantly for us, CO2 is a godsend to man. To boot, it can elevate your coffee experience to a whole new level of awesome. A host of foods you consume daily would taste flat without the benefits of the unique gas.
NDIR CO2 Sensor: The Trusted Carbon Dioxide Sensor
Fortunately, a nifty NDIR CO2 sensor gives you control in this department — ensuring that you have just the right amount of carbon dioxide to make your foods taste as mouth-watering as you want them to be. Read on.
A Vital Gas for the Planet
Right from the onset, we must realize that carbon dioxide is impossible to detect by human senses alone. Not only is CO2 colorless but also it is odorless. However, though far less abundant than nitrogen and oxygen in Earth's atmosphere, carbon dioxide is an important constituent of the air around us.
Table 1: Gases in Earth’s Atmosphere (National Geographic)
Without CO2’s ability to trap heat, our planet would become extremely cold and therefore, inhospitable. In short, we can’t exist without carbon dioxide. Knowing this, it’s no surprise scientists were in a mad scramble to measure the gas.
Early on, mercury manometers were used to measure carbon dioxide. Manometers use the Ideal gas law (PV=nRT) to compute the moles of CO2 taking into account the temperature, pressure, and volume of a dry gas sample. To that end, it employed a U-shaped glass tube filled with mercury to measure gas pressure.
Although mercury manometers are accurate, the procedure can take hours. That certainly won’t make it applicable for industrial use.
The Keeling Curve
The break everyone needed in carbon dioxide monitoring came from one celebrated scientist: Charles David Keeling (1928 - 2005). Tasked by the US Weather Bureau to observe carbon dioxide of the planet, the American scientist began taking hourly atmospheric CO2 measurements at the Mauna Loa volcano in Hawaii. To do that, he used an early infrared (IR) gas analyzer calibrated against his manometer.
Mauna Loa, historically considered the largest volcano on the planet with a height of 4,169 meters, was chosen as the ideal location to take the pulse of Earth’s atmosphere. It is ideally situated for sampling well-mixed air — undisturbed by the influence of local pollution sources or vegetation. Thus, the remote location would allow only carbon dioxide that had mixed with the atmosphere to be measured.
Keeling did groundbreaking research that spanned from 1958 to 2006. Moreover, it revealed to the world the Keeling Curve: the progressive buildup of carbon dioxide in the atmosphere. What’s more, it introduced the merits of infrared radiation to look into CO2 prevalence.
How NDIR CO2 Sensor Works
Today, the most common method to measure carbon dioxide is via the NDIR CO2 sensor. Keeling's original IR gas analyzer was bulky as the sample tube alone was 40 cm or 16 inches long. Still, it used the same principle as today’s widely-used infrared carbon dioxide analyzer.
Figure 1: NDIR CO2 Sensor in Action
The operation of a Non-Dispersive Infrared is quite simple actually. If you take out the technical part, you should be able to understand it in a cinch.
- Gas In: As air enters the sensor, an infrared (IR) light set at the specific wavelengths for CO2 will be activated. Specifically, the IR is set close to the 4.26-micron absorption band of CO2. Matching the light source wavelength serves as a signature or "fingerprint" to identify the CO2 molecule with its unique IR spectrum.
- Length of the Tube: As the IR light traverses through the length of the tube, the CO2 gas molecules absorb the specific band of IR light while at the same time, letting other wavelengths of light pass through.
- Optical Filter: The optical filter is unique. It will let every wavelength of light through except the wavelength specific to CO2 molecules in the air sample tube.
- Infrared Detector: Finally, an IR detector detects the light passing through the filter. It is simply the remaining amount of light that was not absorbed by the CO2 molecules or the optical filter. So, the more CO2 present, the more light will be absorbed. Thus, the amount of light on the other side of the sensor decreases.
Measuring the amount of light left via the infrared sensor will give us the amount of carbon dioxide in the air. Know NDIR sensors have a very long life span. Plus, other substances will also not interfere with readings. These and the fact that it works well at common CO2 ranges makes the nondispersive IR the most widely used carbon dioxide sensor today.
Today, thanks to advances in technology, specifically folded optics and metalized folded plastic that allow light to travel via a curved shape (also known as a waveguide), small-footprint NDIR CO2 sensors happened.
Added to this, light-emitting diode (LED) light sources in circulation allow NDIR sensors to operate at extremely lower power levels. What used to consume 50 to 200mW, now can function 3mW of power. Small wonder, next-gen NDIR CO2 sensors can run on solar energy for months on end.
Carbon Dioxide Monitoring: A Must in the Food Industry
You may be surprised to know carbon dioxide plays a central role in many industries today. We call this CO2 utilization. And this can have a positive impact on the planet’s overall outlook.
Table 2: Industrial Use of Carbon Dioxide
Well, don’t blink now. Know that carbon dioxide use, and thereby carbon dioxide monitoring, is central to the food industry. It comes as no surprise then that the application of NDIR CO2 sensors is rampant in this industry. You may not realize it but many of these food products are a common occurrence in our daily lives. Some of the instances are detailed below.
Statistics show America is a coffee country. In 2016 alone, over 50% of the American population drink coffee daily. That’s over 150 million people taking a cup on a daily basis. Indeed, that shows how much java is loved on this side of the planet.
America is not alone, of course. Nordic countries (perhaps due to all that cold) are top of the list when it comes to coffee consumption.
Table 3: Top 25 Coffee Consuming Nations
The United States is not even ranked as part of the top 10 of that list. The World Atlas states that in terms of coffee consumption, America is top 25.
What many of the world’s coffee buffs do not realize is carbon dioxide has a lot to do with creating a perfect cup. Surprised? Let us explore the nitty-gritty below.
Truth be told, coffee passes through a painstakingly meticulous process to be considered topnotch. Any barista worth his name in salt should be able to tell you that.
You may think that the right temperature matters. And you’re right. It does. Also, you may think that proper procedure in roasting matters. It does too. What many do not know is the right amount of carbon dioxide matters a lot too.
When you roast green coffee beans, that thermal process drives chemical reactions that cause the formation of volatile gases. This buildup increases the volume of the beans by up to 80%. The critical part: Most of which is made up of CO2.
Figure 2: Carbon Dioxide and Coffee Bean Degassing
While some of the carbon dioxides get released in the roasting process, the majority remains in the beans and is gradually released during storage, or more quickly during grinding and extraction. CO2 as a gas is linked to important characteristics of coffee and is a key indicator for freshness.
Moreover, carbon dioxide also plays an essential role in coffee’s shelf life. That means CO2 dioxide can affect the sensory profile in the cup.
What’s more, carbon dioxide plays a central role in the degassing process of roasted coffee beans. Surely, you don’t want a stale cup of coffee. And yet, brewing a coffee straight after roasting can lead you to one disappointing brew.
Degassing is the release of gases from roasted coffee. Taking the time to degas your coffee properly allows the hot water to extract the aromatics and oils from the grinds.
After you roast coffee, gases (i.e., including a lot of carbon dioxide) are released from inside the bean. Many of these gases need a few days after roasting to be released.
The problem is that brewing your coffee too early can result in the creation of small bubbles once you brew your coffee. As a result, these air pockets disrupt the contact that happens between the coffee grounds and the water. When that happens, you have an uneven extraction of the roasted coffee bean’s flavor and aroma compounds.
In short, you’ve just fallen short of your desire to get the best coffee blend. Indeed, if you brew coffee right after roasting, it can negatively affect the flavour and profile of the coffee.
That tells you that if you want to have a most unforgettable coffee experience, minding carbon dioxide content is key.
Everybody knows beer, perhaps even a young child can identify one from an array of canned drinks. America, for one, prefers beer more than any beverage that harbors alcohol. As a matter of fact, the stats say so too.
- 63%: Adult Americans who drink alcohol.
- 42%: Americans who prefer beer over other alcoholic drinks.
- 34%: Americans who prefer wine over other alcoholic drinks.
- 19%: Americans who prefer liquor over other alcoholic drinks.
On average, Americans consume at least 26.2 gallons of beer per drinking adult yearly. One gallon is equivalent to nearly 8 pints. Without a doubt, that’s a lot of beer.
Well, for the uninitiated, you may raise an eyebrow talking about these drinks. But to differentiate, beer and wine, though containing alcohol, are made through fermentation. On the other hand, liquor, also called hard liquor or distilled spirits, is an alcoholic beverage produced by distilling grains, vegetables or fruits. Examples of distilled alcohols are whisky, gin, rum, brandy, tequila, vodka and a variety of flavored liqueurs.
What is increasingly become clear now is that carbon dioxide plays also a central role in the development of the beer. To make beer, you need to cook barley. Once the process is underway, it releases sugar that will be consumed by the yeast in fermentation.
Consequently, the yeast will transform the sugar into two elements: alcohol and CO2. For the most part, the CO2 is released (via an airlock valve) leaving only alcohol in the beer.
Big breweries, on the other hand, use an alternate method called forced carbonation which basically adds the carbon dioxide CO2 into the beer. It does this by using a cylinder of compressed gas. To make it happen, a host of equipment (e.g., pressure gauges, hoses, connectors, regulators) are required using pressurised cylinders. Doing this gives the brewer more control over the volume of CO2 inside the beer to get it ready for consumption in no time.
Why take all the trouble to put carbon dioxide in beer? The answer has to do with taste. As with coffee, the right amount of CO2 defines the beer-drinking experience.
When the beer is carbonated it tastes a lot better. The gas gives a refreshing sensation to the beer. The carbonation is also responsible for the bubbles that create the foam which is important to retain the temperature of the beer.
Truly, a lot has been said about the merits of soft drinks. Many times there, industry observers point out soda is a leading cause of obesity. Indeed, a series of studies have shown how much the consumption of sugary soft drinks has been directly associated with weight gain and the greater risk of obesity in young adults and children.
In a sense, these pundits have been spot on. When you take into consideration how much soda is consumed on a daily basis in America, you can’t help but be alarmed.
45 gallons: the amount of soda average American consumes yearly
470 cans: number of soda cans equivalent of 45 gallons
Now, to put things in context, know that our body consumes but 20 pounds of sugar every year. Having 45 gallons of soda means having roughly 375 pounds of sweet soda every year. So if you’re struggling with diabetes or is carrying too much weight, you may want to take a closer look at your soda intake.
Then again, you may want to know what makes a can of soda tick? Aside from the sugar, be aware that carbon dioxide has a lot to do with it. Small wonder a can of soda is referred to as a carbonated drink.
By putting carbon dioxide in your soda, manufacturers not only ensure the soda fizzes but also that it stays as delicious as possible. Plus, CO2 preserves the drink for a long, long time. Here’s a summary of the reason why carbon dioxide is used in cola drinks.
Table 4: Carbon Dioxide Benefits in Soft drinks
Again, carbon dioxide has become a useful agent to make cola drinks we consume on a daily basis more palatable and delicious. It speaks volumes on the role CO2 plays in putting a sumptuous feast on your table. Imagine how much we would loathe the dining experience with flat-tasting drinks and food.
To Wrap Things Up
To a large extent, carbon dioxide defines much of the food we take every day. Indeed, the list could be exhausting (fizzy drinks, extending fruits/vegetable shelf-life, dry ice). Making sure that you control how much carbon dioxide is at play when processing food is, therefore, a must — telling you why the most widely used carbon dioxide monitor that uses infrared, the NDIR CO2 meter, is essential.