I recently purchased one of these hand held Infra Ref Thermometers (IRT)from http://ift.tt/1FLovEl
At ~$34 it’s nearly twice the price of the cheapest IRT units but this one comes with variable emissivity control, and a thermocouple (TC) for situations where a more reliable measurement of temperature that does not rely on knowing the emissivity of a material.
As to be expected for this price the unit itself is physically lightweight and I suspect it wouldn't handle being dropped all that well so it would have benefitted from a couple of cents worth of rubberised protection on the corners of the unit.. There is also no case, even a basic cloth pouch would be better than nothing.The Fluke IRT we have a work with its robust case, ruggedised external protection and bigger screen makes this unit look a bit like a toy but then it cost 10 times more that this unit, so I am not complaining.
The claimed operating range is -30 to 550ºC
The claimed accuracy is
3ºC or 3% for less than 0ºC
2ºC or 2% between 0 and 100ºC
3ºC or 3% for more than100ºC
The documentation does not say if this accuracy is for the TC or the IR sensor but I suspect it is for the former because the instructions do clearly state that the emissivity of the material will significantly affect the IR temp reading. There is also the question of area of sampling area being considerably greater than for the TC sensor, which effectively samples a point.
I tested a range of temperatures including
The test was done by comparing the measurements of both the TC and the IR sensor on the IRT to the measurement made with a Fluke TC.
Both the TCs for the IRT and the Fluke were Type K TCs.
I twisted the two TCs around each other so they were sampling the same small volume but it was tricky to ensure the IR was sampling the same area as the TCs and in all cases the area sampled by the IR sensor would have been much bigger.
The TC on the IRT did indeed meet the spec with identical readings near zero and at 205ºC
The IR sensor on the IRT was difficult to use to test the exact same area of material being tested, and initial attempts made to adjust the emissivity just added to the confusion.
To make things easier I initially just left the emissivity on the factory setting of 0.95 - more about the emissivity later
Despite these problems the IR sensor was within the spec for all the measurements except for the boiling water where it was 22ºC too low and the Stainless steel jug where it was about 5ºC too high.
This is where I now tried to adjust the emissivity toe see if I could get it to agree with the TC readings but no level of adjustment was able to do this for the boiling water. This could be because the water vapour coming off is affecting the readings. The instructions suggest just measuring the temp of liquids with the TC and then using the IR and use the difference as a way to calibrate the IR but I wonder about how linear that is.
Trying to adjust the emissivity to measure the temperature of the outside of a SS jug was tricky with the temperature jumping around more than for flat objects. Only by firing the laser onto the inside of the flat bottom of the jug could I get the temperature to remain consistent enough to get a reliable reading. Then by adjusting the emissivity to 0.4 the IR and TC agreed but only to within about 0,5 ºC of reproducibility More accurate measurements would probably be obtained by using some sort of clamp to target the IRT onto the same place on the object. Just don't expect readings to within 0.1–C on shiny curved surfaces when it is being used in hand held mode.
Even thought the temperature of the paper was within spec being a flat object I found I could easily adjust the emissivity (to 0.8) to get the TC and IR to agree and hold to 0.1ºC
The IIR also appears to be somewhat sensitive to where any body parts are located relative to the IRT as the IR coming off your hand can affect the results at lwt temperature.
Pros
Battery seems to last a long time. The auto-off and having to deliberately turn on the laser pointer separately probably helps and is a good safety feature
Variable emissivity control is very useful but can be tricky to use for some materials. It’s been a while since I used the Fluke IRT at work but Fluke seemed easier to use but I think that may have been because of the nature of the materials I was measuring.
The TC on the IRT is really useful and with a bit of fiddling allows the emissivity to be calibrated or at least to to check if the emissivity is way out. The TC cannot be used when objects are moving but a TC reading can usually be used to calibrate the emissivity while the object is stationary and then the IR mode can be used after that.
Cons
The display screen is on the small side but typical of its price range and although I can see the main temperature reading without glasses I have to use them to make any adjustments and set the modes.
With only five buttons to control; 6 operational modes, plus the temperature scale, laser on/of, backlight on/off, alarm settings, TC control, and emissivity adjustment, the operation is not all that intuitive and takes some getting used to. Once I got used to it, it was OK and it can be operated one handed except the laser cannot be turn on off easily with just one hand as the trigger must be pulled while pushing a display button.
The unit comes with one A4 page of small font instructions which covers the operation but is thin on detail regarding general usage. The website contains a significant amount of useful background (much more that normally found on an ebay site) but it would have been good to have that information in the printed instructions. The instructions are in what I would call "higher class chinglese" so sometimes I had to read things a couple of times to understand what was going on.
The angle of acceptance is on the large side (12:1) compared to other units which means it senses a spot 12 times smaller than the distance away from the object. The sensing spot is thus 10 mm at 120 mm (and 100 mm at 1200mm) from the object so this makes makes temp measurement of small objects basically impossible. Look for an acceptance angle of around 50:1 if you can.
All in all it’s definitely worth the money and despite the difficulties of measuring some materials and surfaces it seems to do what it claims.
At ~$34 it’s nearly twice the price of the cheapest IRT units but this one comes with variable emissivity control, and a thermocouple (TC) for situations where a more reliable measurement of temperature that does not rely on knowing the emissivity of a material.
As to be expected for this price the unit itself is physically lightweight and I suspect it wouldn't handle being dropped all that well so it would have benefitted from a couple of cents worth of rubberised protection on the corners of the unit.. There is also no case, even a basic cloth pouch would be better than nothing.The Fluke IRT we have a work with its robust case, ruggedised external protection and bigger screen makes this unit look a bit like a toy but then it cost 10 times more that this unit, so I am not complaining.
The claimed operating range is -30 to 550ºC
The claimed accuracy is
3ºC or 3% for less than 0ºC
2ºC or 2% between 0 and 100ºC
3ºC or 3% for more than100ºC
The documentation does not say if this accuracy is for the TC or the IR sensor but I suspect it is for the former because the instructions do clearly state that the emissivity of the material will significantly affect the IR temp reading. There is also the question of area of sampling area being considerably greater than for the TC sensor, which effectively samples a point.
I tested a range of temperatures including
- A near zero ºC ice-water bath
- A painted plaster room wall, a piece of white paper and a SS jug all at around 26ºC
- A white painted piece o steel in direct sunlight at ~50ºC
- An oxidised piece of aluminium at ~50ºC
- A piece of Al painted Black at ~50ºC
- Boiling water at around 100ºC
- The surface of an aluminium electric frypan over 200ºC.
The test was done by comparing the measurements of both the TC and the IR sensor on the IRT to the measurement made with a Fluke TC.
Both the TCs for the IRT and the Fluke were Type K TCs.
I twisted the two TCs around each other so they were sampling the same small volume but it was tricky to ensure the IR was sampling the same area as the TCs and in all cases the area sampled by the IR sensor would have been much bigger.
The TC on the IRT did indeed meet the spec with identical readings near zero and at 205ºC
The IR sensor on the IRT was difficult to use to test the exact same area of material being tested, and initial attempts made to adjust the emissivity just added to the confusion.
To make things easier I initially just left the emissivity on the factory setting of 0.95 - more about the emissivity later
Despite these problems the IR sensor was within the spec for all the measurements except for the boiling water where it was 22ºC too low and the Stainless steel jug where it was about 5ºC too high.
This is where I now tried to adjust the emissivity toe see if I could get it to agree with the TC readings but no level of adjustment was able to do this for the boiling water. This could be because the water vapour coming off is affecting the readings. The instructions suggest just measuring the temp of liquids with the TC and then using the IR and use the difference as a way to calibrate the IR but I wonder about how linear that is.
Trying to adjust the emissivity to measure the temperature of the outside of a SS jug was tricky with the temperature jumping around more than for flat objects. Only by firing the laser onto the inside of the flat bottom of the jug could I get the temperature to remain consistent enough to get a reliable reading. Then by adjusting the emissivity to 0.4 the IR and TC agreed but only to within about 0,5 ºC of reproducibility More accurate measurements would probably be obtained by using some sort of clamp to target the IRT onto the same place on the object. Just don't expect readings to within 0.1–C on shiny curved surfaces when it is being used in hand held mode.
Even thought the temperature of the paper was within spec being a flat object I found I could easily adjust the emissivity (to 0.8) to get the TC and IR to agree and hold to 0.1ºC
The IIR also appears to be somewhat sensitive to where any body parts are located relative to the IRT as the IR coming off your hand can affect the results at lwt temperature.
Pros
Battery seems to last a long time. The auto-off and having to deliberately turn on the laser pointer separately probably helps and is a good safety feature
Variable emissivity control is very useful but can be tricky to use for some materials. It’s been a while since I used the Fluke IRT at work but Fluke seemed easier to use but I think that may have been because of the nature of the materials I was measuring.
The TC on the IRT is really useful and with a bit of fiddling allows the emissivity to be calibrated or at least to to check if the emissivity is way out. The TC cannot be used when objects are moving but a TC reading can usually be used to calibrate the emissivity while the object is stationary and then the IR mode can be used after that.
Cons
The display screen is on the small side but typical of its price range and although I can see the main temperature reading without glasses I have to use them to make any adjustments and set the modes.
With only five buttons to control; 6 operational modes, plus the temperature scale, laser on/of, backlight on/off, alarm settings, TC control, and emissivity adjustment, the operation is not all that intuitive and takes some getting used to. Once I got used to it, it was OK and it can be operated one handed except the laser cannot be turn on off easily with just one hand as the trigger must be pulled while pushing a display button.
The unit comes with one A4 page of small font instructions which covers the operation but is thin on detail regarding general usage. The website contains a significant amount of useful background (much more that normally found on an ebay site) but it would have been good to have that information in the printed instructions. The instructions are in what I would call "higher class chinglese" so sometimes I had to read things a couple of times to understand what was going on.
The angle of acceptance is on the large side (12:1) compared to other units which means it senses a spot 12 times smaller than the distance away from the object. The sensing spot is thus 10 mm at 120 mm (and 100 mm at 1200mm) from the object so this makes makes temp measurement of small objects basically impossible. Look for an acceptance angle of around 50:1 if you can.
All in all it’s definitely worth the money and despite the difficulties of measuring some materials and surfaces it seems to do what it claims.
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