laser thermometer recommendations?

I asked my dad what he wanted for Christmas and he said laser thermometer.

Since I never knew they existed until he mentioned it what do you recommend?

Reply to
David Wilson
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He probably means infrared thermometer. They often have laser aimers.

On my list too :)

Andy

Reply to
Andy Champ

Perhaps he means an infra-red thermometer with laser aiming? The laser is just a gimmic, as the field of vision is usually something like a 30 degree cone, and not the laser dot.

Reply to
Andrew Gabriel

Hi sorry about that, yes that is what I meant, infra red thermometer, point it at something and it tells you the temperature, I wasn't really listening to him when he told me.

Reply to
David Wilson

I have one of these

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and find it useful for 'general interest' measurements round the house and finding local hotspots in electronic circuits and wiring, balancing radiators etc etc. It is only chap and maybe not spot on accurate but it seems to work ok.

Bob

Reply to
Bob Minchin

I have a CEM IR-77L:

It appears to be out of stock at Amazon at present, but there are others. It's useful for wall and rad temp measurements. I think the laser is better than a gimic as it allows to to be sure you're lined up properly.

Added bonus: when fed up with measuring temps, you can use it to annoy the pussy-cats. One of ours runs away when the spot appears in front of her, the other one tries to attack it.

The only oddity is that it insists the outside walls are at -15C.

Reply to
Tim Streater

Not sure whether that remark was intended to be serious or not but with an infra-red thermometer it does matter how good a surface is as an emitter in the infra-red. Unpainted copper pipes seem particularly good at providing a misleadingly low reading at elevated temperatures but not, curiously, at ambient.

A piece of scrap copper lying on the floor gives 19C. The outlet on my insulated hot water tank gives about 25C (scarcely higher than the insulated surface) either side of a piece of black insulation tape wrapped round the pipe while the tape itself enjoys a temperature of about 55C. Has anyone an explanation for this curious state of affairs?

Reply to
Roger Chapman

IIRC a reading from a matt black surface will be the most accurate - if you Google "emissivity" all will be revealed.

Dave

Reply to
NoSpam

Very serious, I was hoping to be able to identify heat leakage spots by taking the temp of the outside of the house. It seemed odd when I took my first outdoor reading, it said -6 or so. As I went round the house it went progressively down to -15, where it stayed as I arrived back at my starting point. Not sure why this should be. My device has emissivity fixed at 0.95, but I thought ordinary brick was not too far off that anyway.

As has been said in another response, look up emissivity, and the emissivity of various materials at different temperatures. When I get a round tuit, I'll prolly get and use some black sticky tape.

Reply to
Tim Streater

These thermometers measure the difference between the emitting surface and the measuring surface, i.e. the active bit inside the thermometer. If the temperature of the thermometer head itself changes during the measurement, it'll throw the result off.

Put the thing outside for a hour, and maybe handle it with gloves, and I'd guess it will give more reproducible results.

Thomas Prufer

Reply to
Thomas Prufer

Errm, how that going to work? How can the designer know what the temp of the measuring surface is going to be? Is the device not going to measure the amount of infra-red it receives at a set number of frequencies and, by comparing them, deduce what the temp of the emitting surface is gonna be?

OK I'll try that.

Reply to
Tim Streater

Devices like the MLX90614 contain a reference sensor in the body of the device. They return two sets of data: the internal device temperature and the "seen" temperature. ref:

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>> Put the thing outside for a hour, and maybe handle it with gloves, and I'd

Reply to
pete

to see the "seen" temperature, that I don't know what the internal temp is for.

Reply to
Tim Streater

Yup. And if the temperature of the device is changing rapidly, the internal device temp will be off more: if the reference sensor is somewhere just a bit aside from the active surface doing the "seeing", and the active bit is heating or cooling (be it to a change in ambient, or to a lot of IR coming in, or whatever), the reference sensor's temp will lead (or lag) the active surface temp. This throws the temp. calculated from internal and "seen" off.

A look through a IR camera is also instructive: a hot, flat, plated metal surface (i.e. chromed fittings on a radiator) can show a wild range of temperatures. The temperature of the metal itself and the temperature of some surface reflected in the shiny bits combine and alternate to give varying readings. Add in that the emissivity will vary between the metal and the reflection...

Thomas Prufer

Reply to
Thomas Prufer

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