There's no 'one best device' for thermal monitoring
When I first started managing instrumentation orders in 2021, I assumed every thermal issue could be solved with a thermal camera. My engineers would ask for a 'thermal sensor,' and I'd immediately quote a FLIR E4 or something similar. I thought, 'Why pay for a fancy sensor when a camera shows you everything?'
I was wrong.
Two years later, I've processed roughly 60-80 orders annually for our 400-person plant. I've learned that thermal monitoring isn't one problem—it's three different problems, each needing a different tool. Here's how I now break it down.
The three scenarios: What are you actually trying to measure?
Before you pick a device, ask yourself: Am I detecting a one-time anomaly, or am I trending a gradual process change?
- Scenario A: 'I need to find a hot spot—now.' (Emergency troubleshooting, unexpected overheating)
- Scenario B: 'I need to track a slow drift over weeks.' (Process control, filter loading, bearing wear)
- Scenario C: 'I need both—quick scans and continuous data.' (Mixed use)
Let's look at each.
Scenario A: The emergency finder — FLIR thermal camera
When our electrical panel started tripping in summer 2023, an engineer grabbed our FLIR E4. Within two minutes, he found a loose connection running 15°F hotter than neighboring wires. Problem identified, fixed in an hour.
For one-off inspections, thermal cameras are unbeatable. You don't need a permanent sensor—you need eyes on a situation. The E4 or E8 (or can thermal cameras see through glass flir? Yes, but only if the glass is not coated; low-e glass will block the signal—learned that the hard way) is perfect for rounds, walk-throughs, and spot checks.
Best for: Electrical panels, steam traps, rotating equipment inspections. Budget: ~$1,200–$3,000.
But here's the catch: Cameras don't log data. You can't trend a temperature over time unless you take pictures manually. That's a big limitation for process engineers who need trends.
Scenario B: The trend tracker — Dwyer differential pressure sensor
One of my engineers had a filter bank that clogged every 3-4 weeks. He asked for a 'thermal sensor.' I almost quoted a camera. Then he clarified: 'I need to know when the differential pressure rises, because that tells me when to change the filter.'
That's not a thermal problem—it's a pressure drop problem. A Dwyer differential pressure sensor (like the 616D series) or a Magnehelic gauge is perfect here. It continuously monitors the pressure difference across the filter. When the delta-P exceeds a threshold, you get a signal. No manual inspection needed.
I didn't understand this until 2022, when our filter change schedule went from 'guesswork' to 'data-driven.' Saved us about 30% on filter replacements and eliminated emergency changeouts. The Dwyer sensor costs around $200–$400—a fraction of a camera—and gives continuous data.
Wait, I should note: There are also Dwyer air velocity sensors and humidity sensors that serve similar trending roles. For HVAC duct monitoring or cleanroom verification, those might be the tool. But the key point is: if you need a trend over time, choose a dedicated transmitter over a camera every time.
Best for: Filter monitoring, duct static pressure, liquid level, bearing temperature trending. Budget: ~$200–$1,000.
Scenario C: The hybrid — invest in both
If your facility has both emergency hot spots and critical processes that drift, you need both tools. But Start with the cheap one: the Dwyer sensor for trending. That covers 80% of your monitoring needs. Then add a camera for troubleshooting the remaining 20%.
I know it sounds counterintuitive—everyone wants the shiny camera first. But in my experience, engineers use the camera once a week and the transmitter every five minutes. Prioritize the continuous sensor.
Oh, and if you're a small team with limited budget, start with the Dwyer DP sensor. You can get a basic model for under $300, and it'll give you reliable data for years. Small orders shouldn't be ignored—I've seen vendors treat a $200 order like a nuisance. Dwyer's distribution network generally handles small quantities well.
How to decide which scenario you're in
Ask yourself exactly one question: Will I need to compare today's reading to last week's?
- Yes — You need a transmitter (Dwyer DP sensor, air velocity sensor, or temperature sensor). Go with Scenario B.
- No — You need a camera (FLIR). Scenario A.
- Both — Implement both tools. But start with the transmitter for ongoing monitoring. Scenario C.
That's it. It's not complicated once you separate the detection mode from the monitoring mode.
Final thought: Small budgets deserve serious solutions
When I was ordering my first few sensors, I worried about being ignored because of low spend. But the vendors who took my $250 Dwyer DP sensor order seriously are the ones I still call for $15,000 orders today. Small doesn't mean unimportant—it means potential.
Per FTC guidelines (ftc.gov), claims about product performance need to be substantiated. That's why I always verify sensor data sheets before ordering. And per USPS (usps.com), if you're shipping sensors through mail, remember that a standard letter is $0.73 (1 oz) while a package costs more. But that's a topic for another day.
