What happens when we stick a thermocouple into a fire? The answer is surprisingly complex and has profound implications for fire safety engineering. In this deep-dive episode, Dr. David Morrisset from Queensland University joins Wojciech to unravel the science of fire measurements that underpins every experiment, test report, and dataset in our field.

The conversation reveals a critical truth often overlooked by practitioners: measurements don't capture reality directly - they capture the interaction between our instruments and fire phenomena. When a thermocouple reports a temperature, it's actually measuring its own thermal equilibrium, not necessarily the gas temperature we assume it represents. This distinction becomes crucial when using experimental data to validate models or make engineering decisions.

The hosts explore various measurement techniques - from temperature and flow measurements to heat flux gauges and oxygen consumption calorimetry - detailing their underlying principles, practical challenges, and hidden assumptions. David shares fascinating insights from his research, including innovative approaches to extracting meaningful data from noisy mass loss measurements and using high-resolution temperature fields to calculate heat fluxes without traditional gauges.

This episode offers essential context for anyone who reads research papers, interprets test reports, or uses experimental data in their practice. By understanding the nuances of how we measure fire phenomena, engineers can better evaluate the quality and applicability of experimental results, recognise their limitations, and ultimately make more informed safety decisions. Whether you're conducting experiments or applying their results, this conversation will transform how you think about the data that drives our field.

I've received a bunch of papers from David to share with you, here we go:

1. Data smoothing - particularly around things like the MLR. This is covered in many papers, and you can start with: https://linkinghub.elsevier.com/retrieve/pii/S0379711222000893
2. The "blue light method" was discussed in the podcast with Matt Hoehler from NIST - I came up with the same kind of effect but with PMMA (using black light instead of blue light) - https://doi.org/10.1016/j.firesaf.2025.104425
3. We did some work on characterising the thermal boundary layer generated by gas-fired radiant panels. https://doi.org/10.1016/j.firesaf.2023.104013
4. In the flame spread work, I did use temperature data to approximate the heat flux acting at the surface https://doi.org/10.1016/j.firesaf.2023.104048

----
The Fire Science Show is produced by the Fire Science Media in collaboration with OFR Consultants. Thank you to the podcast sponsor for their continuous support towards our mission.

The devastating 2018 Camp Fire in Paradise, California serves as a haunting reminder of how rapidly wildfires can overwhelm communities. We have not known anything like it - the flames raced through Paradise at four miles per hour, 30,000 residents had mere minutes to evacuate, and many couldn't escape in time. What happens when the fire goes worse than worst case scenario, but still people need to escape? How do we protect lives when escape routes are blocked by fire or gridlocked traffic?

Dr. Eric D. Link, NIST's researcher in the groundbreaking ESCAPE Project, takes us deep into these critical questions. The project's findings reveal how temporary refuge areas saved over 1,200 lives during the Camp Fire when people couldn't outrun the flames. These ad-hoc safe zones – parking lots, road intersections, and open spaces with reduced fuel loads – provided crucial protection when primary evacuation plans collapsed.

The conversation explores how communities can prepare for these worst-case scenarios by pre-identifying Temporary Fire Refuge Areas (TFRAs) throughout their neighbourhoods. Unlike traditional wildfire safety zones that require enormous clearance, TFRAs offer practical, achievable alternatives that acknowledge the realities of wildland-urban interface communities. The key insight? Even perfect evacuation plans can fail when fires move too quickly, so communities need backup options.

We also delve into the concept of "decision zones" for evacuation planning, the challenges of "no-notice fire events," and the potential for developing dedicated fire shelters that could protect large groups during extreme fire conditions. With climate change intensifying wildfire behavior and more communities at risk, these lessons from Paradise provide crucial guidance for protecting lives when evacuation isn't possible.

Read further on the ESCAPE project findings at the amazing NIST repository (in general, reading the NIST repository is a good life advice :)): https://www.nist.gov/publications/wui-fire-evacuation-and-sheltering-considerations-assessment-planning-and-execution-0

NIST dedicated webpage with more resources, especially for community managers: https://www.nist.gov/publications/wui-fire-evacuation-and-sheltering-considerations-assessment-planning-and-execution-0

Trigger boundaries podcast episode: https://www.firescienceshow.com/156-trigger-boundaries-with-harry-mitchell-and-nick-kalogeropoulos/

Cover image credit: On the morning of November 8, 2018, the Camp Fire erupted 90 miles (140 kilometers) north of Sacramento, California. By evening, the fast-moving fire had charred around 18,000 acres and remained zero percent contained, according to news reports. The Operational Land Imager on Landsat 8 acquired this image on November 8, 2018, around 10:45 a.m. local time (06:45 Universal Time). The natural-color image was created using bands 4-3-2, along with shortwave infrared light to highlight the active fire. Officials evacuated several towns, including Paradise. They also closed several major highways.
NASA, Joshua Stevens - https://earthobservatory.nasa.gov/images/144225/camp-fire-rages-in-california

----
The Fire Science Show is produced by the Fire Science Media in collaboration with OFR Consultants. Thank you to the podcast sponsor for their continuous support towards our mission.

The world looks entirely different through a thermal camera lens, especially in a fire scenario. These devices reveal harsh temperature gradients between hot and cold surfaces, adding another dimension to how fire safety professionals understand and navigate dangerous environments.

Thermal cameras have transformed firefighting operations with astonishing effectiveness. Studies show that in smoke-filled buildings, thermal cameras have significantly improved the changes to identify victims. This technology dramatically reduces search times and increases survival chances, making it an essential tool for modern fire services around the world.

Martin Veit, who recently completed research for the Fire Protection Research Foundation, takes us deep into the science behind these life-saving devices. He explains how thermal cameras detect long-wave infrared radiation (7-14 micrometres) emitted by objects based on their temperature, creating images that reveal what smoke would otherwise conceal. The technology works because many combustion gases are relatively transparent in this part of the spectrum, giving firefighters a crucial advantage in zero-visibility conditions.

We explore the fascinating distinction between "measuring" precise temperatures (which requires understanding factors like surface emissivity and a bit of physics) and simply "observing" temperature differences (which can be sufficient for navigation and victim location). This distinction proves crucial when evaluating how thermal cameras should be tested and certified for firefighting applications.

The conversation delves into the challenges of current testing methods under NFPA standards, which sometimes yield inconsistent results that don't align with human perception of image quality. Martin's research investigates alternative approaches from the field of image processing that could provide more reliable and relevant evaluations, potentially improving both camera certification and opening doors to AI-assisted applications in firefighting.

Read the Martin's report here: https://www.nfpa.org/education-and-research/research/fire-protection-research-foundation/projects-and-reports/measuring-thermal-image-quality-for-fire-service-applications

----
The Fire Science Show is produced by the Fire Science Media in collaboration with OFR Consultants. Thank you to the podcast sponsor for their continuous support towards our mission.