Published August 21, 2026 at 14:42
Infrared measurement has a characteristic that is easy to overlook precisely because it is so obvious: it always measures the surface. The radiation captured by the instrument comes from the outermost micrometers of the material and nothing else. It does not matter how good the optics are or how accurately the emissivity is set — whatever lies beneath the surface is completely invisible to the method.
Most of the time this does not matter, because the surface is exactly what you are after: a hot connection, a binding bearing, leaking insulation. But often the question is different. How hot is the medium inside the pipe, not the outside of the pipe? How hot is the winding, not the motor housing? How hot is the product inside the packaging? That is where infrared ends — and that is why this instrument also features an input for a thermocouple.
What it is
The FLIR TG56 is a spot IR thermometer with 30:1 optics — the measurement spot diameter is the distance divided by 30, meaning small targets can be measured from a safe distance. It features a thermocouple input, a color display with a graphical menu structure, and shows the current reading alongside the previous two simultaneously. The rugged build withstands a three-meter drop, and the instrument is supplied with a traceable calibration certificate.
The problem it solves
The two measurement principles complement each other precisely where the other falls short.
Infrared is fast and safe. You measure from a distance without touching anything — which is the entire point around energized equipment, rotating machinery, or hot surfaces. With 30:1 optics, you can also target an individual component from several meters away instead of getting an average of everything surrounding it.
The thermocouple is slower, but gets to the core. An immersion probe reaches into the medium, a surface probe provides solid contact against metal that is too shiny to measure optically — and shiny metal surfaces are the classic weakness of the IR method, as they reflect the surroundings instead of emitting thermal radiation themselves. Contact measurement does not care about emissivity at all.
Having both in the same instrument does more than just save space in your tool bag: it lets you cross-check one against the other. If an IR reading looks suspect on a bare metal surface, you can verify it on the spot with contact measurement — giving you two readings from the same unit, with the same calibration and the same documentation, rather than two separate instruments that may or may not agree.
Having the display show the two most recent measurements alongside the current one might sound like a small detail, but it reflects how troubleshooting actually works in practice. You rarely compare against an absolute limit; you compare phase to phase, bearing to bearing, one side to the other. With three values visible simultaneously, you make the comparison in your head right at the machine, instead of jotting down notes and calculating afterwards.
Three typical use cases
- Electrical and switchgear: fast IR scanning of connections and fuses from a distance, with contact measurement for verification where surfaces are shiny.
- HVAC and process piping: IR for insulation and surfaces, thermocouple for the actual temperature of the medium.
- Maintenance: comparison between identical components — bearings, motors, phases — where the delta between the units is what truly matters.
Why it pays off
The costly part of troubleshooting is not taking the measurement, but drawing the wrong conclusion. An IR reading from a shiny metal surface taken as absolute truth can cause overheating to be dismissed as normal; a surface reading assumed to represent the fluid inside can lead to the opposite — a process throttled or adjusted unnecessarily. Both errors stem from using the method beyond what it can answer, and both are avoided by having the alternative principle right in the same hand.
Then add the documentation: with a traceable certificate, the reading holds up as solid evidence in a report, to a supplier, or during an inspection. A value that cannot be tied to a calibrated instrument is just a note; one that can is a certified measurement result.
