Laser IR Thermometer

[DHutch]

Does anyone one have a IR Thermometer, the beam type you point at an object and get a temperature?

I'm looking at getting one for the steam boat, not a £580 posh one, but one of the more affordable spec levels. Obviously it won't be as durable and have the same level of accuracy, but I was wondering what to look out for.

A bit like the Uni-T DC clamp meters everyone recommends.

 

 

Daniel

[mross]

I have one that cost about £20.  It does not have the laser pointer; it doesn't need it.  The laser has no part in the measurement.  Lasers seem to deceive people into taking measurements from a distance,  To get a 'spot' measurement you need to be within a few inches.

Here is a great range https://thermometer.co.uk/21-infrared-thermometers

[dmr]

I got a really cheap one from ebay, probably this one......

https://www.ebay.co.uk/itm/Digital-Infrared-Handheld-Temperature-Gun-Thermometer-Non-Contact-IR-Laser-Point/332426284743?epid=1756017825&hash=item4d66268ec7:g:tZEAAOSwyGZZ8ZGh

The laser gave up after about a year of very occasional use, but otherwise it still works.

I believe these devices have fundamental accuracy limitations due to surface radiation characteristics, they really don't like looking at shiny copper pipes for example.

For this reason it hardly seems worth getting an expensive one.....or maybe the expensive ones compensate in some way????

..............Dave

[mross]

What you can do is stick some masking tape (or similar) on a pot of boiling water and then adjust the emissivity until it reads 100 deg C.  Then you can stick the same tape on other things and get a fairly accurate reading.  So make sure your gadget has adjustable emissivity.

[system 4-50]

Just don't point the laser at your Ecofan. The resulting explosion of speed will destroy it's bearings.

[WotEver]

I have one. It seems pretty good for a guide. I have no idea how accurate it is across the range but pointing it at a simmering saucepan reads 99C so that seems pretty good to me. 

[frahkn]

4 hours ago, DHutch said:

Does anyone one have a IR Thermometer, the beam type you point at an object and get a temperature?

I'm looking at getting one for the steam boat, not a £580 posh one, but one of the more affordable spec levels. Obviously it won't be as durable and have the same level of accuracy, but I was wondering what to look out for.

A bit like the Uni-T DC clamp meters everyone recommends.

 

 

Daniel

I bought a cheap one (£50 or thereabouts). It came in a case and (apart from a day or so when new) it has been there ever since. A bit like the remote camera which I bought at the same time. And my DC clamp meter, come to think of it.

Whenever I think any of them would be useful at home (not very often) the're on the boat and vice versa.

Edited December 3, 2017 by frahkn

[mross]

I have Flir IR camera that attaches to my phone.  It's brilliant.  I use it to check radiators, house insulation, and all sorts.  But it was £200.

[Taslim]

12 hours ago, dmr said:

I got a really cheap one from ebay, probably this one......

https://www.ebay.co.uk/itm/Digital-Infrared-Handheld-Temperature-Gun-Thermometer-Non-Contact-IR-Laser-Point/332426284743?epid=1756017825&hash=item4d66268ec7:g:tZEAAOSwyGZZ8ZGh

The laser gave up after about a year of very occasional use, but otherwise it still works.

I believe these devices have fundamental accuracy limitations due to surface radiation characteristics, they really don't like looking at shiny copper pipes for example.

For this reason it hardly seems worth getting an expensive one.....or maybe the expensive ones compensate in some way????

..............Dave

I bought one of those.  The 'laser' still works on my one.

It's a very useful tool especially around batterys and electrics.  You can pick up on a delinquent cell or a poor connection quickly and is great for finding an out of balance cylinder on elderly engines. 

We had thermal cycling problems with some kit at work and the firm bought an expensive 'accredited' one for £Ouch!  Fluke I think.  My cheapo gave more consistent and accurate results.

Edit to add.  Get some heat conductive tape if you are going to use it for spot measurements on glittery engines.  No prob if you are just trend spotting though.

Edited December 3, 2017 by Taslim

[WotEver]

They’re also used by some kit car owners Dan. Tyre pressure is a bit of a guess with a kit car so go for a run and when you stop check the tread temperature in the centre and two edges. If the centre is much higher then the pressure is too high and vica versa. 

[Psycloud]

The cheap ones are great and generally agree with the other temperature devices on the boat so am happy with it's accuracy to be within a range that I need (i.e within a degree or 2 at low temps and within a ballpark at 200+ degrees).

 

[dmr]

1 hour ago, Taslim said:

I bought one of those.  The 'laser' still works on my one.

It's a very useful tool especially around batterys and electrics.  You can pick up on a delinquent cell or a poor connection quickly and is great for finding an out of balance cylinder on elderly engines. 

We had thermal cycling problems with some kit at work and the firm bought an expensive 'accredited' one for £Ouch!  Fluke I think.  My cheapo gave more consistent and accurate results.

Edit to add.  Get some heat conductive tape if you are going to use it for spot measurements on glittery engines.  No prob if you are just trend spotting though.

Yes, comparative measurements are where they are really good, and most measurements are comparative or else do not require the ultimate in accuracy. Looking at stove flue temperatures is a really good use for these. I have also got some proper thermocouples on the boat, plus a proper digital readout, trouble is you have to find a good way to fix the thermocouple to get correct heat transfer, and wait for it to stabilise, so usually I prefer the cheapo infra red device.

Another big advantage(?) is that they are so quick to use that you measure all sorts of interesting things that you would not normally bother with. How many boaters know how much their baseplate temperature varies over the year???

I use mine to check that the dog is still alive, she breathes so slow and shallow when she goes into her deep nighttime sleep.

[DHutch]

Thanks all.

I was recommended to paint a black spot on each area, both to get around the variable emissivity issues and to make sure your testing the same place each time, or there about. If you can get tape for the job then even better. Valid point about being able to adjust the emissivity to calibrate its at say 100deg using simmering pan, which is likely enough for comparative work on a steam plant. 

I realise the laser is not measuring, just giving a guide, and that the distance has to be fairly small, but if your trying to hit a 15mm copper pipe one of the cheaper ones might be hard to use. £6 seems far to cheap to work, but maybe it isnt? I will have a look at the thermometer.co.uk site.

 

Daniel

[frahkn]

12 hours ago, dmr said:

Yes, comparative measurements are where they are really good, and most measurements are comparative or else do not require the ultimate in accuracy. Looking at stove flue temperatures is a really good use for these. I have also got some proper thermocouples on the boat, plus a proper digital readout, trouble is you have to find a good way to fix the thermocouple to get correct heat transfer, and wait for it to stabilise, so usually I prefer the cheapo infra red device.

Another big advantage(?) is that they are so quick to use that you measure all sorts of interesting things that you would not normally bother with. How many boaters know how much their baseplate temperature varies over the year???

I use mine to check that the dog is still alive, she breathes so slow and shallow when she goes into her deep nighttime sleep.

Hey, that's a brilliant idea.

I sometimes wake up and wonder if the dog and the wife are alive or dead - neither of them have learnt to manage a deep, robust snore, despite my good example.

Strange thing is, if I give the wife a good solid nudge and ask if she is asleep, I get nothing but abuse, quite unlike the dog who doesn't seem to care - or in any event, doesn't resort to foul language.

[mross]

It's worth noting the 'field of view'.  For example, mine views a circle of 10" diameter at a distance of 10".  Some have a finer 'cone'.  Some of the expensive ones have a ring of laser dots to show you.

[Tonka]

On ‎02‎/‎12‎/‎2017 at 20:40, mross said:

What you can do is stick some masking tape (or similar) on a pot of boiling water and then adjust the emissivity until it reads 100 deg C.  Then you can stick the same tape on other things and get a fairly accurate reading.  So make sure your gadget has adjustable emissivity.

Don't you have to be at "standard atmosphere" for water to boil at 100 deg C.

[mross]

26 minutes ago, Tonka said:

Don't you have to be at "standard atmosphere" for water to boil at 100 deg C.

???????? please add a smiley if you are attempting a witticism.  Or are you serious?    Even 1,000 feet above sea level you would only be out by one degree.

There's a good calculator here to determine the effect of atmospheric pressure on boiling point. http://trimen.pl/witek/calculators/wrzenie.html

So long as the barometric pressure stays between 960mbar and 1050mbar, you'll still be within one degree!

Edited December 4, 2017 by mross

[DHutch]

On 04/12/2017 at 07:48, mross said:

It's worth noting the 'field of view'.  For example, mine views a circle of 10" diameter at a distance of 10".  Some have a finer 'cone'.  Some of the expensive ones have a ring of laser dots to show you.

That looks like the exact one I had (probably still have...) for measuring the temperature of RC car engines, but in this instance I want a much tighter cone.

 

Daniel

[mross]

Most of the units on Amazon have a distance to spot ratio of 12.  But that still means you are measuring the average over an area of one-inch diameter at a distance of twelve inches.

[DHutch]

1 hour ago, mross said:

Most of the units on Amazon have a distance to spot ratio of 12.  But that still means you are measuring the average over an area of one-inch diameter at a distance of twelve inches.

Yeah, which seems reasonable, and tighter then my unit.

At say three inches, as close as I can practically get, the spot is down to circa 6mm which you can get on a 15mm copper pipe, or most other fittings. I presume that lost by the curve of the pipe is not and issue in terms of getting a repeatable and reasonably accurate reading?

 

Daniel

[mross]

6 minutes ago, DHutch said:

I presume that lost by the curve of the pipe is not and issue in terms of getting a repeatable and reasonably accurate reading?

No, that won't affect the accuracy.  But I would paint or tape the copper.  The 'default' emissivity is 0.95 but look at the various values for copper here.

https://www.engineeringtoolbox.com/emissivity-coefficients-d_447.html

 

Edited December 6, 2017 by mross

[Chewbacka]

As my pipes are more like the "Copper heated and covered with thick oxide layer" rather than the "Copper Polished" the error is not so great.  Never understood why people buy chrome towel radiators as the heat output is a fair bit down on painted, especially the radiant heat which is what feels nice and warm when you stand near them.