Smoke Signals: Measuring the Invisible
Smoke Signals: Measuring the Invisible
Noel Putaansuu
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Since the earliest settlers braved North America’s coldest weather, the use of wood combustion has served as a reliable heat source. Even today, consumers here in the U.S. and around the world rely upon wood-burning stoves and pellet heaters as a pleasant and efficient way to heat interior living spaces.
According to the U.S. Environmental Protection Agency (EPA), there are approximately 13 million wood and pellet stoves in use today in the United States alone. Although our modern power grid is reasonably stable, outages do occur—often during the worst weather—prompting many in rural areas to resort to wood combustion to heat their homes, which adds to the number of wood-burning stoves and heaters in use.
Wood-burning stoves offer a cozy and efficient way to heat your home. It is good, reliable heat that requires little power (if any) to receive the welcome heat. This having been said, traditional wood-burning can release harmful pollutants into the air. These pollutants, including particulate matter and post combustion gasses, can contribute to air pollution and negatively impact health.
To address this issue, innovative technologies are emerging to make wood-burning cleaner and safer. By investing in advanced solutions, we can enjoy the warmth of a wood fire without compromising our health, the environment, or heat comfort.
By investing in advanced solutions,we can enjoy the warmth of a wood fire without compromising our health, the environment, or heat comfort.
Defining the Problem
The problem can be defined as the smoke particles emitted from the chimney. Wood smoke exposure presents risks, particularly for vulnerable populations such as children, the elderly, and individuals with pre-existing respiratory conditions. To mitigate these risks, it is essential to adopt cleaner heating and cooking practices and promote the use of low-emission technologies.
To combat these particle emissions, innovative technologies are emerging to mitigate the impact of wood smoke pollution. By investing in cost-effective and portable solutions, we can protect our health and preserve our wood heat atmosphere.
Humans perceive smoke at a distance by how light interacts with the smoke particles. As you drive by a house on the road during daylight hours, smoke is viewed as gas cloud eddies with particles that travel some distance from the chimney. The darker the smoke and the farther it travels results in our minds as more smoke emissions. At night in low light conditions, our sense of smell prevails as more sensitive to smoke.
This article is brought to you by Associated Energy Systems.
Smoke Complaints
Smoke measurement is a growing science—from fire safety smoke detectors in the home, to PM 2.5 monitors for air monitoring, to smoke opacity measurement for chimneys (including pellet and wood stoves), which is under close study.
Smoke police or smoke complaint investigations are started by an observer (victim) that files a complaint to the air quality agency. This agency is the enforcement division, and it is directed to act on complaints received. The enforcement agency has multiple levels of response or reaction, ranging from (1) a warning postcard or citation being sent to the address of the smoke plume, (2) a site visit investigation by local authorities, or (3) a levying of fines.
Smoke Laws by Location
Washington State, for example, limits chimney smoke opacity (how much light it blocks) to 20% for six minutes at a time. Anything thicker and longer could lead to enforcement actions. Smoke can’t bother neighbors either, with exceptions for initial startup. Burn bans make any emissions illegal (though there are exceptions, like power outages).
The Old-Fashioned Way: The Ringelmann Method
So, how do we measure smoke? The current method approved by the EPA is Method 9 Visual Opacity and involves comparing the smoke plume to a chart with black and white squares (the Ringelmann method). It’s not exactly high-tech!
Figure 1: Ringelmann Scale 1 is 20%, 2 is 40%, 3 is 60% 4 is 80%
The Science of Smoke Measurement
Trained observers take smoke readings from a public area, disregarding water vapor condensation (a common chimney output). It’s important to note that this water vapor can be misinterpreted as smoke, and most of what a person sees coming from a chimney is water vapor condensing.
Figure 2: Wager Model 6500 Smoke Meter
The Future of Smoke Measurement: Enter Smokeless Chimney!
The good news? Smokeless Chimney is pioneering a new method using an Octoring smoke meter with a light source and sensor. We’re collaborating with a national laboratory on this project, testing pellet stoves and wood stoves.
Standards and Flexibility: Why Smokeless Chimney Is Different
While American Standard Testing and Materials (ASTM) standard testing equipment exists, our “Octoring” system offers more flexibility. It’s designed to be a monitor as well as a control signal generator for combustion systems, allowing us to adjust light colors and sensors for optimal measurements.
Beyond Opacity, Unveiling the Mysteries of Smoke
Among the advantages of this technology is the data collected delves much deeper than opacity readings, which are easy to understand but incomplete for understanding the characteristics and content of smoke. In our research, we’ve determined that there are far more complex factors essential to creating a full profile of smoke. One of these is “ColorShift,” a metric we developed that complements opacity readings, especially during low-opacity situations.
A Peek Into the Wood Stove Burning Stages
Here’s a simplified breakdown:
- Cold Stove Startup: Larger smoke particles cause “Mie scatter,” blocking and scattering light.
- Operating Temperature: At this stage, there’s no visible smoke, but “ColorShift” indicates smaller particles scattering blue light (the Tyndall effect).
- Fuel Refueling: This results in a short term rise in opacity and ColorShift.
- Embers (Tail): At this point, opacity is near zero, but ColorShift may indicate very small particles.
Science in Action
This research is currently under peer review, so it’s early days. However, we have great scientists, interns, and innovators, and we’re using the scientific method to gather data and uncover new insights.
Beyond the Hype: Separating Myth From Reality
The Tyndall effect explains why blue light scatters more readily. Think of the red sun setting on a smoky day. This indicates the presence and size range of smoke particles. Our technology might shed light (pun intended!) on particles as small as 40 nanometers, far smaller than the human eye can detect.
The Road Ahead
While this is all theoretical for now, it could revolutionize our ability to measure smoke particles beyond the standard PM 10, PM 2.5, and PM 1 classifications. To put that in perspective, a PM 2.5 particle is 2,500 nanometers, and a nanometer is a billionth of a meter!
Science Is a Journey
I love exploring new scientific discoveries. However, some media outlets might sensationalize this research, portraying wood stoves and pellet stoves as invisible particle factories with residential chimneys puffing out billions of unseen particles.
Before jumping to conclusions, we need to delve deeper into this theory. This includes analyzing microscopic particle data.
Trust in Science
Our team includes dedicated scientists who are committed to a rigorous scientific approach. So, let’s keep exploring and unlock the secrets of smoke together! We can improve all wood and pellet stoves, even existing wood stoves for safety, efficiency, and emissions.
Noel Putaansuu
Noel Putaansuu is the Owner of Smokeless Chimney. With more than 35 years of experience in the fire sciences, he has participated in the industry from the research and development perspective, and he has also managed a large portion of the U.S. fire claims for insurance companies. He believes in warm homes and clean air for everyone.
