I just acquired a 60 gallon air tank and am going to document my build here. Does anybody care to double-check my calculations?
Here's what I have so far:
The tank is 20" in diameter. The length of the tank is 37" weld to weld. The rounded end caps are about 6" each, for a total of 49" (approximately). Given that it's 60 gallons, it's 13860 in^3 in volume.
The FB/CC opening, area under RF plate, and area at the end of the RF plate will need to be at least 55.44 in^2. To achieve this, the inside of the firebox top will be at 5" from the bottom of the tank. This will provide 61 in^2 of area.
The FB needs to be at least 4573.8 in^3. I am planning a 20x18x18 outside dimensions firebox for a total of 5971.871 in^3.
FB air inlet needs to be at least 13.86 in^2.
Exhaust needs to be at least 305 in^3. I plan on going with 36" of 3.5" i.d. pipe for 346 in^3.
Here's a diagram I drew up to scale. Comments enthusiastically welcome!