For those that did not understand how a HP refrigerant flow is established here is a cute little diagram showing the state of refrigerant in both heating and cooling mode.
Its my fault assuming that it was understood that the compressor and the dryer being connected with a short section of copper is in essence the same temp during operation. I was trying to get someone to explain to me why the image did not indicate the same temp on the copper line as the dryer and the compressor indicated. It really was not a complicated issue just multiple issues Emissivity, Reflectivity due to multiple sources of heat being distributed in multiple directions by a rotating fan blade drawing air from the cold evaporator. The situation I captured in this image is just an example of what one can expect to deal with in any outdoor situation hot spots cold spots reflecting on each other and wind blowing
The image I posted was a raw image had not been thermally tuned as I would have accomplished if this had been on a paying job.
Not all are aware that emssivity and reflectivity can be adjusted in the software focus is the only item that can not be adjusted
Great discussion, even the debating. I got to admit I follow Chuck a little easier than Charley but that’s just because he is the run-on-sentence king. I have a couple questions:
Is it true or partially true to say that emissivity and reflectivity are two sides of the same coin in some respects? And…
Wouldn’t any guess of either of those two factors be somewhat arbitrary when it comes to a copper pipe, mainly because the labelling the exact tarnish level is also arbitrary?
Not to mention atmospheric attenuation is very minimal in long wave inside of what would be considered normal distances, which is the biggest benefit to using a LW imager.
As a side note, the Testo 890-2 has an add on probe that will auto correct the atmospheric conditions. I wish they had a built in laser pointer/distance meter to correct that as well.
Jason Kaylor
AC Tool Supply
Net Zero Tools
877-207-1244
For surfaces that are opaque to infrared, emissivity and reflectivity factors are complimentary (i.e., when you add the two they come to 1.00). They are inversely proportional to one another. A theoretical black body has and emissivity of 1.00, so no radiation would be reflected. This is why calibrations are done using black body simulators. If you aim your imager at an object that has an emissivity of .95, 95% of the incident radiation that you imager is receiving is being emitted by that object, while 5% is being reflected from other objects. This can be compensated for as long as you actually know the emissivity and the reflected temperatures. As a rule, as emissivity goes down, accuracy goes down, fast. Emissivity is one of the most critical factors to consider when you need to determine actual temperature or compare objects of different emissivities. As long as emissivity is fairly constant and you are not trying to determine actual temperatures, it’s a non-factor, which it why you can scan the interior of a building looking for moisture or insulation deficiencies without fretting over emissivity.
There are many factors that have an effect on emissivity that include: material itself; temperature - objects may change emissivity as temperature changes; Viewing angle - the further from perpendicular the lower the emittance; Surface condition - polished vs. tarnished or rough; Geometry - shape affects emittance (cavities have higher emittance).
Have you ever wondered why the hex socket in a feeder lug looks hotter than the outside? It’s due to the higher emittance provided by the geometry (cavities don’t reflect well and as we know from the complimentary relationship, when reflectivity goes down emittance goes up).
Most of this stuff is level-II, but it’s important for anyone using an infrared imager to understand the concept and how it affects real vs. apparent temperatures, especially if you attempt to compare two objects with different characteristics.
You can normalize emissivity differences or increase emittance by using 3M electrical tape, as mentioned earlier. 3M tape has a known emissivity of .95 (don’t try this on things that are energized, moving, too hot to touch or otherwise hazardous). So you can accurately measure the temperature of a shiny piece of metal if you place a known, high emissivity target on it and give it time enough for the temperature to normalize.
Sorry for missing the invite.
It’s Christmas (can I say that word?), and time for me to have another bout with medical issues… The Big “C” present this year…
Had my head in my A** your right on the muffler I just did not pay attention the MFG are starting to put dryers inside and that was what I had on my mind
No one said anything was to hot your dreaming again. You are getting like chuck all I was drawing attention to was the difference in the discharge line and the compessor temp No big F*** deal so there:D
Glad I was able to make your face as red as your HAT!
I just mentioned too hot so camera owners don’t start running around calling that stuff out!
“For everyone else” Scroll compressors (as this one) have very “hot heads”. Many have a high temperature sensor on them because of their design. The cool suction refrigerant gas enters below the scroll (see Charley’s pic). This is as it should be.
Rotery compressors also are like this. And they also have mufflers!
I have a couple questions: