Small hot spot using temp. gun

daveferns1 · Oct 4, 2019

Hey guys so I have a basking spot that is some sort of fake rock i got from my local reptile store, I think it is made of some kind of hard plastic.

Anyway the highest part of the fake rock (to the left of the branch) get to around 105-107F pretty much all over using a temp. gun. The branch leading up to it only reaches around 90-95F. Also there is a small hot spot maybe less than inch diameter circle that tends to heat up more on the rock, gets to around 110F maybe even 111F. The hammock also doesn't store heat well.

The idea was he can use the hammock and branch to get up to the fake rock at 105F and then can use the branch or hammock (for UVB basking also) as a gradient of heat . My main concern is the small hot spot on the fake rock but you guys can give any opinions of the tank. Thanks!

BeardedDragonSteve · Oct 4, 2019

daveferns1":1nbjrzut said:
Hey guys so I have a basking spot that is some sort of fake rock i got from my local reptile store, I think it is made of some kind of hard plastic.

Anyway the highest part of the fake rock (to the left of the branch) get to around 105-107F pretty much all over using a temp. gun. The branch leading up to it only reaches around 90-95F. Also there is a small hot spot maybe less than inch diameter circle that tends to heat up more on the rock, gets to around 110F maybe even 111F. The hammock also doesn't store heat well.

The idea was he can use the hammock and branch to get up to the fake rock at 105F and then can use the branch or hammock (for UVB basking also) as a gradient of heat . My main concern is the small hot spot on the fake rock but you guys can give any opinions of the tank. Thanks!

That is a heat rock and you need to get rid of it immediately and get a basking bulb and fixture. Because bearded dragons can not feel belly heat and heat rocks can easily burn in some thinner parts of the plastic. The tank looks good but get rid of the heat rock and is the uvb T5 or T8

Claudiusx · Oct 4, 2019

What bulb are you using?
Some of the reptile bulbs have a pretty narrow beam of heat they put off.

What do your temps read if you use a probe end?

It's really not too much of a concern but I like bulbs that dont produce hot spots like that. I like a wider area of heat output.
Tank looks great.

-Brandon

daveferns1 · Oct 4, 2019

It doesn't have a cord or anything its just like a plastic fake rock, you are probably right tho about the thin parts. I did measure all surfaces of it and the highest part only reaches 111F, I am thinking about taking it out tho.

daveferns1 · Oct 4, 2019

claudiusx":1duysta7 said:
What bulb are you using?
Some of the reptile bulbs have a pretty narrow beam of heat they put off.

What do your temps read if you use a probe end?

It's really not too much of a concern but I like bulbs that dont produce hot spots like that. I like a wider area of heat output.
Tank looks great.

-Brandon

Its a 45 watt halogen flood light, Ive always been concerned cause most people have higher power lights in there 40 gallon breeders but this 45watt seems to get the temps right. I dont have a metal probe thermometer but I do have an exo terra combo meter that is for like ambient air temps that I used to place directly on the basking surface and would get readings around 105F. The flood light is also in a 8.5inch ceramic lamp.

daveferns1 · Oct 4, 2019

BeardedDragonSteve":2daq7g43 said:
The tank looks good but get rid of the heat rock and is the uvb T5 or T8

Its a 10.0 t5 in a t5 HO hood about 12inch from basking spot but the screen is right below it obviously .

edit: the only cord i have in the tank is the cord for the combo meter probe (probably the cord you see) just so people dont think im using an electric heat rock, but if just a hard plastic rock is still bad i will probably take it out.

CooperDragon · Oct 4, 2019

Your UVB light is at a good distance. I've noticed some hot spots like that with my temp gun too. It is either the reading off of the surface (readings will vary depending on the surface type using an IR gun) or it could be a hot spot created from the glass/lens on the basking light. The temps are in a good range so I wouldn't worry too much about it. If he avoids the area then you might want to make a small tweak to bring the temp down. Otherwise I don't think it will be harmful.

Claudiusx · Oct 4, 2019

The plastic rock is fine I wouldnt worry about it.
I only asked about the probe end thermometer because some materials give inaccurate readings to most commonly set ir thermometers.

-Brandon

daveferns1 · Oct 4, 2019

Again thank you so much guys! My juvenile will be coming tomorrow so just wanted one final check to make sure it was ok.

CooperDragon":1nevi7xw said:
If he avoids the area then you might want to make a small tweak to bring the temp down. Otherwise I don't think it will be harmful.

Yea I bought a 60 dollar gun from Home Depot so I expect it to be at least pretty accurate, and I used it at the right distance away, I think cause the rock is different colors Im getting slightly different readings. I will take your advice and if he avoids it I will try lowering the temps slightly.

claudiusx":1nevi7xw said:
The plastic rock is fine I wouldnt worry about it.
I only asked about the probe end thermometer because some materials give inaccurate readings to most commonly set ir thermometers.

-Brandon

Yea I was reading up on it, I think the main problem is I dont know the exact material the fake rock is made out of. Its a IR gun for measuring home surfaces so Im sure it should work on hard plastic. Thanks again Brandon you've given me so much info!

CooperDragon · Oct 4, 2019

As mentioned, don't worry over it too much. If you're in the ballpark that tends to be good enough. The focus should be more on creating gradients and your dragon will move about to choose what they want at a given time.

If you'd like to do some further reading on what we're mentioning regarding the readings against different surfaces, you may want to check through this thread in the advanced discussion section. https://www.beardeddragon.org/forums/viewtopic.php?f=87&t=249355

daveferns1 · Oct 4, 2019

Ok Ill try not to worry about it too much, I think I offered a decent enough gradient and Im gonna put his hide in in a week so that might help. The emissivity is preset to .95 on my gun and I was looking at plastics and black is .95 and wood is around .85 - .9 based on types maybe this is why Im getting a slightly lower reading on wood?

Anyway Im sure it will be fine as long as I dont cook him, Ill make sure to stay on the safe side and decrease temps if he is avoiding it.

kingofnobbys · Oct 4, 2019

Are you "shooting" the temperatures from above or is such a way that you are likely to be "seeing" the reflection of the basking globe ( on a sloped glossy surface if "shooting" from the side :
… if you are there is a strong likelihood you are introducing "specular errors" ( measuring the temperature of the reflection of the basking globe ---> results in higher temperatures than the actual surface temperature if the emissivity is set correctly. Very common mistake , even professional engineers and physicists fall for this error.

This explains what is going on viewtopic.php?f=34&t=241233

If the surface emissivity is know , and your gun is preset at e = 0.95 , you can compensate for the emissivity error
viewtopic.php?f=34&t=239064&p=1833542#p1833542
the equation is

daveferns1 · Oct 4, 2019

kingofnobbys":3717n3av said:
Are you "shooting" the temperatures from above or is such a way that you are likely to be "seeing" the reflection of the basking globe ( on a sloped glossy surface if "shooting" from the side :
… if you are there is a strong likelihood you are introducing "specular errors" ( measuring the temperature of the reflection of the basking globe ---> results in higher temperatures than the actual surface temperature if the emissivity is set correctly. Very common mistake , even professional engineers and physicists fall for this error.

This explains what is going on viewtopic.php?f=34&t=241233

If the surface emissivity is know , and your gun is preset at e = 0.95 , you can compensate for the emissivity error
viewtopic.php?f=34&t=239064&p=1833542#p1833542
the equation is

I was kinda shooting like diagonally so I will try from straight above and only 2inches away and also 8inches away, see if I get any different readings. Regarding emissivity I think I kinda get whats going on, my main problem is I dont know the exact wood im using, and for the fake rock im guessing its paint over the top so I should use that emmisivity, which is probably acrylic. Also if I did want to attempt the formula im just confused what I would use for background temp, the area around the hotspot?

kingofnobbys · Oct 4, 2019

daveferns1":238fex3v said:
kingofnobbys":238fex3v said:

Are you "shooting" the temperatures from above or is such a way that you are likely to be "seeing" the reflection of the basking globe ( on a sloped glossy surface if "shooting" from the side :
… if you are there is a strong likelihood you are introducing "specular errors" ( measuring the temperature of the reflection of the basking globe ---> results in higher temperatures than the actual surface temperature if the emissivity is set correctly. Very common mistake , even professional engineers and physicists fall for this error.

This explains what is going on viewtopic.php?f=34&t=241233

If the surface emissivity is know , and your gun is preset at e = 0.95 , you can compensate for the emissivity error
viewtopic.php?f=34&t=239064&p=1833542#p1833542
the equation is

Click to expand...

I was kinda shooting like diagonally so I will try from straight above and only 2inches away and also 8inches away, see if I get any different readings. Regarding emissivity I think I kinda get whats going on, my main problem is I dont know the exact wood im using, and for the fake rock im guessing its paint over the top so I should use that emmisivity, which is probably acrylic. Also if I did want to attempt the formula im just confused what I would use for background temp, the area around the hotspot?

Tsensor [K] is the temperature measured by the infrared radiometer (brightness
temperature),
Ttarget [K] is the surface temperature of the target,
Tbackground [K] is the brightness.
(Temperature of the background (T(air) at the location).

The equation works, I used it in the 1990s when I invented, designed and fabricated an inhouse "gas pyrometer" when I was working as research furnace engineer and was able to measure the gas temperature inside furnaces ( a very hard temperature to measure , there was nothing available commercially that could handle temperatures about 1600 degC ).
Air basking spot air temperature thermometer must be shielded from line of site IR from the heatsource to be correct ( T air (ONLY) ).

Small hot spot using temp. gun

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