OK guys, here is a question for 1K or less roasters that have an exhaust pipe coming out of their cyclone and are plumbing it somewhere.

What temperature does the pipe wall present to the wall that the pipe is going through?

What precautions are necessary to keep combustible materials from going up in flame??

Can you touch that pipe with your bare hands comfortably?

I am planning for the install of a Bella Taiwan mini500 and would like to have everything ready for it when it gets here.

Thanks in advance

I did some temp measuring on my Huky a couple of years ago. The temp in the exhaust bowl (the standard exhaust system for the Huky 500) was 60-70C (140-160F). My current exhaust system is a PVC plastic cyclone attatched to a plastic bucket with a lid. While it gets warm, it doesn't go above 50C (120F) or so, i.e. the exhaust pipe (out from the cyclone) are warm but touchable. My 4" exhaust pipe then cools off rapidly for every foot it's extended out the window.
(I bought the plastic cyclone just for tests and to see if it works, but as it shows no signs of suffering from the temperature of the exhausts, I found no reason for exchanging it with a much more expensive metal cyclone.)
If your cyclone is metal, it should be even better in cooling the exhausts.

Thanks Bjorn

I have been over thinking/worrying about it way to much I think.

SF-1 Exhaust Pipe
I have dryer vent from the roaster through the wooden wall.
The roaster was fired up and running at 490F. The air leaving the drum metered at 400F with the metal of the bean chute metered at 245F using IR thermometer. The cyclone was metered at 235F at the top and 135F at the bottom. The exhaust flow is from top to bottom and then up the middle to the exhaust pipe. The pipe ranged from ~100F to ~80F. I could continually hold the it in the photo.

Excellent Moshe! Thank you.