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Quick explanation why your gun is probably not accurate

PostPosted: Fri Mar 23, 2018 6:35 pm
by kingofnobbys
[TOPIC AUTO-LOCKED DUE TO INACTIVITY]

Very common for a gun to be recommended to measure temperatures in a viv , BUT likely the temperature gun is :
>>> not being used correctly ( if reading high you may be measuring ONLY surface temperatures and be introducing a systematic error due to the gun seeing the reflection of the basking globe on a "reflective" surface , an error called a specular error.
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>>> incorrect emissivity setting programmed into the gun for the surface being measured by the , if the surface actually has a higher emissivity , the temperature measurement will be too low, and conversely if the emissivity of the surface is actually lower, the temperature will be too high :
Image
and
>>> very common for amateurs to shoot the temperature from TOO FAR AWAY , it is very important that the area you to measure FILLS the measurement spot , if you are too far away , the gun will see & measure background too , which may be either a lot cooler (most likely in a viv) or a lot hotter , and it will simply indicate the average. SO if the gun has a spot specification of 12:1 , this means the spot is 1 inch in diameter at 12 inches from the surface, so your spot needs be larger than the measurement spot ( you come closer ) to ensure the spot is filled.

The digital thermometer is the measurement I'd take as being reliable and accurate provided it's had time to reach thermal equilibrium and is either
>> in physical contact the surface if you want to measure the surface temperature
>> suspended in the media (air) if you want only radiant heat and air temperature.

Re: Quick explanation why your gun is probably not accurate

PostPosted: Mon Mar 26, 2018 10:51 am
by AHBD
Very interesting. I can see that it would be very easy to get the wrong temps. with ALL of the different types of thermometers because people use them differently and there is probably variation in reliability of individual products as well.