63.3 Gallon Tank Calculations

[Malcolm B]

So I started with an 80 gallon air tank, but the original length of 45.5" was a little too long. I cut a section out and re welded the cap back on to reduce the length down to 36". This gives it an original displacement of 18480cid and 80 gallons, reduced to 14622cid and 63.3 gallons.

1) Using the Smoking Meat Forums calculator, the recommended area for my FB.to CC opening should be about 58.5ci. I am also using the "1728 circle calculator" to find my opening area. I've got 4.53" in Segment height to get 58.581 inches of area. If I understand this correctly, the RF to CC area must also be pretty near this calculation, but a little larger is ok (to promote positive airflow), correct?

2) Firebox area should be 4825.25cid. In order to maintain my chord length from the circle calculator (18.54in), my firebox must also have an inside width of 18.54". I am thinking 19"H x 18.54"W x 19"L. This gives a total displacement of 6693cid or about 138% of the minimum size. Referring back to my other thread about firebox design, this maintains more of a square shape. Would this height and length suffice or should it be made taller and longer?

Lastly, this is unrelated to my calculations but does someone have a good design for grease trays and drains? I would really like to incorporate one fur simplicity of cleaning the smoker! Thanks in advance!

 

[radioguy]

I built a RF similar in size. Consider the calcs as guidelines. Your FB to CC is about right, you can go a bit bigger if you want. I just made my RF plate to CC opening about 15% larger than FB to CC. FB size is good to, just size it to match up to CC. Consider door placement and fire management.

RG

 

[Malcolm B]

I was thinking of the door facing the same direction as the door of the CC. I planned to put the intake vents beneath my fuel rack and cross-flow vents directly across from FB to CC opening. Both on the same side, and from what I've read thus far, in-line with the flow of air.

This may be a dumb question as my common sense is telling me if I go with a larger opening, everything else in turn must be changed to match. So here goes; Does changing the size of the FB to CC opening require me to change the minimum area of the intake vents and cross-flow vents in the firebox? Though I don't plan on doing a massive change, for simplicity's sake, I may go with a larger FB to CC opening.

 

[radioguy]

You can increase the size of air intakes by the same percentage, within reason. I made mine 15% larger, you can always shut them down with damper.

RG