How does it work?

[Yadkin]

Originally Posted by Giraffe (He/Him)

I know this’ll take a level of attention you’re not accustomed to but pay attention mope;

The can’t is you.

Yeah sure.

[ZipZap]

Originally Posted by Tikiman

Good to know. I've been using mine anywhere from 6" to 12" without any noticeable difference of temperature readings, but I imagine there is a limit to what it can do.

You asked for it...

Actually did some design work for IR cameras back in the day.

First, the laser is just a pointer and has nothing to do with the sensor.

IR energy is produced at wavelengths just below the visible spectrum (sorry, no discussion on quantum, so I'm sticking to waves). It can be focused with silicon lenses just like visible RF. The IR spectrum is actually divided into two somewhat distinct regions, near and far. We "feel" the near IR, which is closest to visible. There are some interesting things about far IR, but I won't digress. Your tool measures in the near IR range. Once focused through a lens, the energy impinges typically on a "thermopile". Why thermopile? It is literally a pile of thermocouples, similar to the bi-metal thermocouples that you have as a flame sensor in your NG HVAC. A pile is needed to amplify the small amount of IR energy into a useful signal. The energy is measured against a reference inside the unit in a thermally stable block. The delta-T creates electricity in proportion to the delta, and is measured by electronic circuitry and processed into the display as "absolute" temperature. As far as distance from target, the lens used has a field-of-view. If the target is smaller than the FOV, then the sensor is seeing area around the target along with the target. Good sensors actually publish the FOV in the form of "Distance to Spot" ratio. It specifies how far away from the target the sensor can be to obtain an accurate reading. If the D/S is 10, a 2" diameter object needs to be read at less than 20" (10:1 x 2). Your pizza stone probably easily fills the FOV of your sensor at 12". Shooting duct work from 15 or 20 feet becomes much more problematic.

[Aerovette]

I have a black truck and have used it to measure the surface temperature on a hot summer day.

[Giraffe (He/Him)]

Originally Posted by Mick

One thing most people "know" but never really think about is that you can't see water vapor in air, it is completely invisible. That is why even though there is pretty much always some water vapor in the air around you (humidity), you can't see the air. Let the air drop below the "dew point", and you get fog, which is condensed water vapor.

Back in ancient times when I was a young engineer, we didn't have fancy infra-red detectors like that. If we sprung a high pressure steam leak, you could hear it, but could not see it because it was so hot, it stayed as vapor until it cooled down. So we would hear a steam leak, and the outer portions of the building were fogging up as the steam condensed, buy you couldn't see exactly where the leak was. The common method to finding it is a guy would walk around with a broom stick, and when he saw the end of the stick disappear (because the live steam had sheared it off), that's where the leak was.

Thankfully, in my job, I never had to be the "broomstick guy".

40 year Steamfitter. I'm familiar believe me.

[Tikiman]

Originally Posted by ZipZap

You asked for it...

Actually did some design work for IR cameras back in the day.

First, the laser is just a pointer and has nothing to do with the sensor.

IR energy is produced at wavelengths just below the visible spectrum (sorry, no discussion on quantum, so I'm sticking to waves). It can be focused with silicon lenses just like visible RF. The IR spectrum is actually divided into two somewhat distinct regions, near and far. We "feel" the near IR, which is closest to visible. There are some interesting things about far IR, but I won't digress. Your tool measures in the near IR range. Once focused through a lens, the energy impinges typically on a "thermopile". Why thermopile? It is literally a pile of thermocouples, similar to the bi-metal thermocouples that you have as a flame sensor in your NG HVAC. A pile is needed to amplify the small amount of IR energy into a useful signal. The energy is measured against a reference inside the unit in a thermally stable block. The delta-T creates electricity in proportion to the delta, and is measured by electronic circuitry and processed into the display as "absolute" temperature. As far as distance from target, the lens used has a field-of-view. If the target is smaller than the FOV, then the sensor is seeing area around the target along with the target. Good sensors actually publish the FOV in the form of "Distance to Spot" ratio. It specifies how far away from the target the sensor can be to obtain an accurate reading. If the D/S is 10, a 2" area object needs to be read at less than 20" (10:1 x 2). Your pizza stone probably easily fills the FOV of your sensor at 12". Shooting duct work from 15 or 20 feet becomes much more problematic.

Thank you.

[Mick]

Originally Posted by Giraffe (He/Him)

40 year Steamfitter. I'm familiar believe me.

I got the feeling OSHA wasn't real thrilled with the practice.

[Giraffe (He/Him)]

Originally Posted by Mick

I got the feeling OSHA wasn't real thrilled with the practice.

I never actually saw that being done but I've heard of it.

I've done some actual steam blows starting up boilers. All kinds of shit get's left inside pipe. Weld rod stubs, files, gloves, you name it. When they did the steam blow at Sherco 3 it was so loud the local cows stopped producing milk.

Sherco 3 is a BIG MoFo coal fire. 900 MW.