Non-contact Infrared thermometer

[Dave]

Looking to buy an infrared thermometer without breaking the bank and also without knowing exactly what I'm looking at - for instance, what is "emissivity" and does it need to be adjustable?

I'm sure that these are the sort of things that are bought for one purpose but actually end up being used for dozens of things and I'm sure I'll find loads of uses for it, but my main use at the moment would be to monitor temperatures of GPUs and CPUs on laptop motherboards.

I live about a mile away from CPC in Preston and have seen this one for £43 inc VAT:

have experience of them? Good? Bad? Anything better for absolutely no more than £60, but preferably £50 or less?

TIA

[newshound]

>> or > Anyone have experience of them? Good? Bad? Anything better for

I have something unbranded but similar looking, and a smaller cheaper version (no laser). I think they would be fine for CPU temperatures, they are also good for balancing radiators. I stick a bit of black PVC tape on the valve when doing this in the belief it should improve the accuracy. For most purposes you don't need absolute accuracy to less than a couple of degrees. In theory results should be less reliable on shiny metal surfaces (google emissivity for more details). If you were using it (say) for process control where accuracy was important you could always calibrate it against a thermocouple (and then you would have to decide whether you need a calibrated thermocouple). My guess is that they might have similar errors to cheap thermistor based devices. But they go up to much higher temperatures.

[Dave]

>>>>> or >>> Anyone have experience of them? Good? Bad? Anything better for

Cheers Newshound, I think I'll treat myself tomorrow then lol

[Simon Cee]

Have a look at

2 types, £10 or £16. I've otrdered a few bits from them, decent quality and cheap cheap cheap.

Chinese sense of humour too... If I use this IR thermometer to take someone's temperature, will they feel anything? No, absolutely nothing. They will not even know you are taking their temperature. Is this thermometer safe? Yes. This thermometer uses infrared to read temperatures, which is perfectly safe. Just make sure that you don't shine the laser into anyone's eye! If you want to measure the temperature of someone's eye, please use a different device.

Non-Contact Infrared Thermometer with Laser Targeting and Emissivity Adjustment

Infrared Thermometer with Laser Targeting/LCD Display

[Tim Streater]

Was there some reason you were unable to look it up?

[ARWadsworth]

> or > Anyone have experience of them? Good? Bad? Anything better for

Best cat toy you will ever buy:-)

If you are not in a rush to buy one Maplins often do half price sales on them. Paid about £20 for mine.

[Simon Cee]

Oops, that should be

[Dave]

Tim Streater explained :

Yes. I'm thick. Rather than read lots of confusing big words, I just wanted someone to say yes, these are good little gadgets or no, they're a waste of money. Or for someone to say, that's not a bad one but this one is better.

[newshound]

>>> or >>> Anyone have experience of them? Good? Bad? Anything better for

Good call, I think my little one may have come from there. Maplins have a load of stuff on offer at the moment anyway. But you probably *do* want one with a laser to check CPUs.

[John Rumm]

Some surfaces radiate better than others. So when making an estimate of the temperature based on the IR being emitted the device has to take this into question. The cheaper meters will make a fixed assumption about this. They work well on most surfaces, but will be fooled by reflective things and shiny metal etc. o you could read the temperature of a radiator for example, but would not get a sensible reading from the pipework or valve's body.

Hence one with adjustable emissivity might be handy since you could be looking at unpainted heatsinks.

fine.

I have a simpler one that works well, but would not be as well suited to your application.

[Tim Streater]

:-)

John's explained about emissivity (but I still think you could have got that info yourself). While he's right that a variable emissivity device will be useful in more situations, generally you can take emissivity to be 0.95, fixed, which is what the cheaper devices do. This covers most surfaces except shiny ones, so you'll get a decent result off a rad painted black or white, but not a shiny chrome one.

I have one of these and it does a decent job on my rads. I got the one with the laser pointer which is fun. One cat chased the spot around, the other immediately ran away and hid.

I think the device also has to make some assumptions about the ambient temperature, too, but someone else can prolly explain that better. All I know is I went round the outside of the house in winter and by the time I'd been all the way round it was measuring the outside wall temp of the house at -20C - unlikely.

Variable emissivity is all very well, but ISTM you'd want it to dial up "chrome", "white paint" etc, rather than a number.

[Martin Brown]

Although black dry marker pen is reasonably effective and reversible as a way to make the emissivity non-metalic. Though you can sometimes be unlucky and find a surface that has pores and marks permanently with dry marker.

Basically any shiny metal behaves to some extent as a reflector of IR wavelengths. Most resin paints and common materials are black in the thermal IR including glass windows.

Regards, Martin Brown

[fred]

I'm sure mine was from Maplin when on special, was def under 20quid _and_ has a laser. Haven't seen them at those prices (either at Maplin or CPC) for ages though.

[fred]

Aaaaand you can see how hot and bothered the cat is getting . . .

[John Rumm]

Worth noting that if you do want a reading of something metal and shiny, then sticking a bit of tape on it will usually suffice to get a reading.

[newshound]

I'd love to find a reference for your comments on paints. I have a work job at the moment where this is a very real issue. IR spectra by ATR show relatively narrow absorption bands with high transmission in between. These are paints on blast cleaned (i.e. rough) steel. Are we getting absorption at the metal-paint interface? Coating thickness is

200 - 250 microns, two pack epoxy and polysiloxane "white" paint.

TIA Steve

[Martin Brown]

It is a slight over simplification but basically true for most paints.

Work in this area is not much in the open literature but some is for the paints used on major observatory domes. Brief intro here a few searches on ADS abstracts should get you more detail:

the old way was to use extremely white paint to keep solar heat out of big observatory domes. Now they use a cunning mix of white and aluminium to get thermaly neutral paint at night. Otherwise the dome surface supercools to the night sky and cold air drips in through the open dome slit producing local severe turbulence in the seeing.

Other variants include base coat clear technology where the undercoat is shiny metallic to reflect most light and the top coat varnish is as close to being black in the thermal IR band as they can make it.

Another intro:

are military applications to adjusting your thermal IR emission signature.

Is the white TiO2 pigment? I am a physicist and not a proper chemist but I can ask my wife who is tonight. I have no experience with ATR.

Asking your paint supplier tech support is probably your best bet.

Regards, Martin Brown

[newshound]

Thanks, that is fascinating. I hadn't thought about observatory domes before. We are looking at "off the shelf" industrial paints where solar heating is sometimes of interest, but IR performance doesn't normally matter. Last time this came up the client had some emissivity measurements done at Cardiff.

The suppliers are a bit coy about their formulations; I'd expect the top coats to contain plenty of TiO2, but when I get some samples I will pop them in an SEM!

Steve

[Steve Firth]

Phamer wrote: [snip overlong rant]

And... Relax. I assume that you can spot the hypocrisy that your rant represents? If you don't want to see the posts that you complain about use your kill file.

[whisky-dave]

Yep I'll support that if fact that's pretty much all mines used for now.=20 Brought from Maplin for about =C2=A325.=20