Let’s face it, monitoring what’s going on inside a furnace that’s running at over 1000°C isn’t exactly a walk in the park.
LAND® have been doing it for years with their water-cooled borescope cameras, but what happens when water isn’t readily available on site?
That’s where air-cooled borescopes come in. This development lets us permanently look inside some of the hottest industrial environments on the planet using only instrument air as the cooling medium, without risking damage to the camera or other critical components.
Over the past few years, we’ve been putting these borescopes through their paces in real-world applications to refine our design. The goal? Keep the camera cool while using as little air as possible.
Why use Air-Cooled Borescopes?
Capturing
thermal images inside furnaces, reformers, and crackers, where temperatures can soar past 1200°C allows process optimisation, early hot spot detection and can even improved production yields. The challenge is keeping the camera cool enough to survive, which we have been doing for many years but with our water-cooled jacket.
Without water the challenge is significantly harder. That’s where the air-cooled jacket comes in. It channels multiple layers of air around the borescope to protect it from the heat. But how much air is enough and what happens if you don’t get it quite right?
Lesson 1: Real-World Testing Beats Theory
Sure, we could run simulations. But when it comes to heat transfer, airflow, and unpredictable furnace environments, real-world testing tells the full story. Across multiple sites, we tested different jacket designs, flow rates, and installation setups to see what works best, and what delivers the lowest viable air flow rates.
Lesson 2: Not All Jackets Are Created Equal
We tested three main designs:
Standard Water-Cooled Jacket with Air Flush: Lasted about 4 minutes before overheating. Not ideal.
Drilled Jacket: A significant improvement. Multiple air paths pushed air into the furnace, allowing permanent installation at 1200°C with stable temperatures. However, thermal expansion cracked the weld at the front during a two-week trial.
Drilled Jacket & Vortex Coolers: Provided cooler air, but not enough of it. Turns out, the flow rate matters more than air temperature.
The final air-cooled jacket design combines the benefits of the drilled jacket with a flexible outer tube that expands and contracts with temperature changes, preventing damage during heat-up and cool-down cycles.
Lesson 3: Flow Rate Is Everything
We found that once you get close to the minimum viable flow rate, even small changes can cause big temperature spikes. That’s why it’s so important to dial in the right numbers and leave a bit of a safety margin.
This is one of the key reasons why we recommend using independent flow meters and flow control for each of the three air connections.
Here’s a rough guide based on our trials, you can see the potential difference between good and bad installations:
| Function |
Flow Rate (LMP) |
| Cooling Air |
150-750 |
| Purge Air |
90-512 |
| Standpipe Air |
50 |
| Total |
300-1100 |
Lesson 4: Installation Makes a Huge Difference
Some setups required significantly less air than others. Why? Factors like furnace draft, good insulation, and proper probe alignment made a noticeable impact. On the other hand, poor sealing or awkward positioning meant we had to increase airflow to keep temperatures within safe limits.
Lesson 5: Long-Term Durability Still Needs Testing
Short-term trials gave us confidence in the designs, but we wanted to understand how the jackets would perform over months or even years of continuous use. Working with some of our key customers, we ran extended pilot projects and were very pleased with the results. These trials confirmed our belief that the design and material choices were robust and reliable.
We also made a practical improvement by adding a threaded connection between the outer and middle tubes. This means the outer tube can be easily replaced if it ever becomes worn or damaged, without needing to replace the entire assembly.
Smarter Monitoring with Thermal Imaging and Borescopes
Pairing these
borescopes with high-resolution
thermal cameras unlocks a whole new level of insight:
•
Real-time Tube Metal Temperature (TMT) monitoring
•
Early hotspot detection before failures occur
•
Integration with plant control systems for smarter, data-driven decisions
Final Thoughts: Smarter Monitoring Starts Here
This development process has allowed us to fine-tune the design and performance of air-cooled borescopes for some of the harshest environments in industry. The key takeaways?
•
Flow rate is critical
•
Installation quality matters
•
Real-world testing beats theory
•
Thermal imaging adds significant value
We’re excited about the future of this technology and how its helping operators run safer, more efficient, and more reliable processes.
Click here to learn more about our borescope technology