Help getting started

[swflsmokr]

Hello, I am new to reverse flow smokers, and need some help with the fire box to cook chamber opening. I have a 5 foot section of 24 inch 5/16 wall pipe for my cook chamber. My fire box will be a 2 foot section of the same 24 inch 5/16 pipe. How do I figure the open from fire box to cook chamber? Second question is 1/4 plate thick enough for closing the ends and for the reverse flow plate? If not my next option is 3/8. For the stack I am planning on using a 4 inch pipe that is 1/4 wall. Finally, I plan to trailer mount this for ease of moving and transporting. Thank in advance for the advice!

 

[ghoster]

hi, 

I've plugged your figures into the calculators posted by DaveOmak, and the below is what I came up with.

CC Diameter	Cook Chamber inside diameter (inches)	23.38
CC Length	Cook Chamber inside length (inches)	60.00
CC volume	Diameter X Diameter X 0.7854 X Length = Volume in cubic inches	25,748.11
FB/CC opening	Volume in cubic inches X 0.004 = FB/CC opening in square inches	102.99
Rec. under RF plate	Volume in cubic inches X 0.004 = Area under the RF plate in square inches	102.99
area at end of RF plate	Volume in cubic inches X 0.004 = Area required at the end of the RF plate in square inches	102.99
Recommended FB Volume	Volume in cubic inches X 0.33 = minimum volume of the Fire Box	8,496.88
Recommended FB air inlets	Volume in cubic inches X 0.001 = FB air inlets in square inches...	25.75
FB Diameter	Firebox inside diameter (inches)	23.38
FB Length	Firebox inside length (inches)	24.00
FB volume	FB Diameter X FB Diameter X 0.7854 X FB Length = Actual Firebox volume in cubic inches	10,299.24
Exhaust Stack	Volume in cubic inches X 0.022 0.017  = Exhaust Stack Volume in cubic inches	566.46

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Your FB/CC opening will need to be at least 103 sq inches.  If your using the two sections of pipe, use the segment calculator to work out the height of your segments.

http://www.1728.org/circsect.htm

From the above, needing at least 103 sq inches, the below are the figures I got.  The segment area is half of what you need, because your total area will be made up of two identical segments, from the cc and the fb. 

		Inches
Segment Height ED	4.2
Apotherm OE	7.49
Radius		11.69
Chord AB		17.951
Central Angle	100.31
Arc AB		20.466
Circumfrence	73.45
Segment area	52.399
Triangle Area	67.255
Sector Area	119.62
Total Circle area	429.32

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• ghoster
• Jan 3, 2017

All of the calculator and material above is courtesy of DaveOmak. Look up the post "
[h1]Standard Reverse Flow Smoker Calculator... by DaveOmak and others... Ready to use.. rev5.. 6/19/15......[/h1]
Note the figures are minimums.  Your Firebox will already be larger than the min.  You should consider increasing the other sizes above the minimums, but you probably want more experienced builders jumping in here to help.

 

[SmokinAl]

Just click on the reverse flow calculator at the top of the reverse flow section.

Or here is the link.

http://www.smokingmeatforums.com/a/reverse-flow-smoker-how-to-calculate-build-tutorial

Al

 

[ahumadora]

1/4" is way thick enough for capping the ends and reverse flow plate,  I use 3/16" most of the time to save $. (diffference building for yourself or building to feed the family.)

I use 2  x    #16  (1.6mm)  4" tubes for my 24" cookers.  Again the little bit of heat dissapation between #16 and 1/4" thickness is not going to change to performance of your cooker much.