I have recently purchased a 500 gallon propane tank to build a custom smoker. I need help figuring out the firebox configuration to support this big smoker. Does anyone have any suggestions or resourses I can access. Any and all help will be greatly appriciated.

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## 500 Gallon propane tank smoker

### #2

Posted 17 July 2009 - 10:03 PM

scotty828, on Jul 17 2009, 03:27 PM, said:

I have recently purchased a 500 gallon propane tank to build a custom smoker. I need help figuring out the firebox configuration to support this big smoker. Does anyone have any suggestions or resourses I can access. Any and all help will be greatly appriciated.

Scotty, here is a pit ratio calculator I used to build my pit. The guy did a great job and many have used it.. if you have any questions P.M me.

http://webpages.charter.net/tomchism/BBQ%2...0Calculator.htm

### #3

Posted 20 July 2009 - 05:36 PM

I need somone to explain to me how to use that ratio chart . Sorry call me dumb.

"It's not what buy, it's what you build"

### #4

Posted 20 July 2009 - 08:54 PM

I just opened the Excel file and might have some tips. If you have a round firebox (I do) then I entered "0" for the first dimensions for the "Square or rectangular in inches" in cells B7, C7, and D7. This also makes a "0" value in all the other areas so you don't get confused on the numbers. I think yellow is what you enter and light blue is what you need. My smoker has a 34" wide cooking/smoking chamber that is 15.5" diameter. It has a 17" wide firebox that is 15.5" diameter. This makes my firebox 3,206.41 in^3 and 1/2 the cooking/smoking chamber and the rule of thumb at the bottom of the sheet says it should be 1/3 (but I'm okay if it is larger than 1/3 I just wouldn't want it to be smaller).

I skipped Row 14 as this was a "0" value for my round firebox. My exhaust chimney should have a volume of 160.31 (that looks like 5% of the firebox volume) and then it asks for the diameter of the chimney and mine is 3" and this notes that the length of the chimney should be 22.69" but it is actually around 14" though I'm not sure what the importance of this being 22" is (maybe to get the smoke above your face so it doesn't blow into your eyes?). If mine were another 8" higher it would be aggravating to reach up six and a half feet to keep adjusting the vents (and my wife wouldn't be able to reach it).

For the air inlet opening it is a bit more math for me and it is late. Mine is a typical round opening with 2 pie pieces missing out of 4 pie pieces and the air inlet damper can fully cover or uncover the openings. The total air inlet is about 8" diameter and Pi*r^2 gives me 50.27 in^2 but half of that is permanently closed so only 25.13 in^2 max with the middle 2" diameter taken by the mounting of the damper (or 1.57 in^2) so that gives me about 23.5 in ^2 though the sheet doesn't allow for that so I hand-entered the number into cell F25.

The Firebox to cook chamber opening says it should be 159.4 in^2 but it is the top half of the round firebox overlapping the bottom half of the smoking chamber to it looks like a cat's eye turned sideways and I don't know a calculation for this area. It is 15.5" x maybe 8" square but subtract half of a 4" x 4" corner or 8 in^2 from each of the four corners. That is 124 in^2 - 4*(8 in^2) = 92 in^2. I don't know that this is right as it could be higher. Still, the numbers are not too far off the ratio calculator.

Hope that helps.

I skipped Row 14 as this was a "0" value for my round firebox. My exhaust chimney should have a volume of 160.31 (that looks like 5% of the firebox volume) and then it asks for the diameter of the chimney and mine is 3" and this notes that the length of the chimney should be 22.69" but it is actually around 14" though I'm not sure what the importance of this being 22" is (maybe to get the smoke above your face so it doesn't blow into your eyes?). If mine were another 8" higher it would be aggravating to reach up six and a half feet to keep adjusting the vents (and my wife wouldn't be able to reach it).

For the air inlet opening it is a bit more math for me and it is late. Mine is a typical round opening with 2 pie pieces missing out of 4 pie pieces and the air inlet damper can fully cover or uncover the openings. The total air inlet is about 8" diameter and Pi*r^2 gives me 50.27 in^2 but half of that is permanently closed so only 25.13 in^2 max with the middle 2" diameter taken by the mounting of the damper (or 1.57 in^2) so that gives me about 23.5 in ^2 though the sheet doesn't allow for that so I hand-entered the number into cell F25.

The Firebox to cook chamber opening says it should be 159.4 in^2 but it is the top half of the round firebox overlapping the bottom half of the smoking chamber to it looks like a cat's eye turned sideways and I don't know a calculation for this area. It is 15.5" x maybe 8" square but subtract half of a 4" x 4" corner or 8 in^2 from each of the four corners. That is 124 in^2 - 4*(8 in^2) = 92 in^2. I don't know that this is right as it could be higher. Still, the numbers are not too far off the ratio calculator.

Hope that helps.

Yoder Smokers (circa 2009) Cheyenne model w/convection plate - charcoal smoker/grill with side firebox (375 lbs and made from 1/4" plate)

Nexgrill (circa 2009) #720-0649 model - 3 main burners, 1 sear burner, 1 rear burner gas grill with rotisserie kit

Terra Cotta (circa 2006) - home-assembled smoker (soon to be dismantled)

Sunbeam (circa early 1990s) - 2 burner gas grill (soon to be discarded)

Habachi (circa late-1970s) - charcoal (soon to be discarded)

Nexgrill (circa 2009) #720-0649 model - 3 main burners, 1 sear burner, 1 rear burner gas grill with rotisserie kit

Terra Cotta (circa 2006) - home-assembled smoker (soon to be dismantled)

Sunbeam (circa early 1990s) - 2 burner gas grill (soon to be discarded)

Habachi (circa late-1970s) - charcoal (soon to be discarded)

### #5

Posted 20 July 2009 - 09:56 PM

Darren S, on Jul 20 2009, 09:54 PM, said:

I just opened the Excel file and might have some tips. If you have a round firebox (I do) then I entered "0" for the first dimensions for the "Square or rectangular in inches" in cells B7, C7, and D7. This also makes a "0" value in all the other areas so you don't get confused on the numbers. I think yellow is what you enter and light blue is what you need. My smoker has a 34" wide cooking/smoking chamber that is 15.5" diameter. It has a 17" wide firebox that is 15.5" diameter. This makes my firebox 3,206.41 in^3 and 1/2 the cooking/smoking chamber and the rule of thumb at the bottom of the sheet says it should be 1/3 (but I'm okay if it is larger than 1/3 I just wouldn't want it to be smaller).

I skipped Row 14 as this was a "0" value for my round firebox. My exhaust chimney should have a volume of 160.31 (that looks like 5% of the firebox volume) and then it asks for the diameter of the chimney and mine is 3" and this notes that the length of the chimney should be 22.69" but it is actually around 14" though I'm not sure what the importance of this being 22" is (maybe to get the smoke above your face so it doesn't blow into your eyes?). If mine were another 8" higher it would be aggravating to reach up six and a half feet to keep adjusting the vents (and my wife wouldn't be able to reach it).

For the air inlet opening it is a bit more math for me and it is late. Mine is a typical round opening with 2 pie pieces missing out of 4 pie pieces and the air inlet damper can fully cover or uncover the openings. The total air inlet is about 8" diameter and Pi*r^2 gives me 50.27 in^2 but half of that is permanently closed so only 25.13 in^2 max with the middle 2" diameter taken by the mounting of the damper (or 1.57 in^2) so that gives me about 23.5 in ^2 though the sheet doesn't allow for that so I hand-entered the number into cell F25.

The Firebox to cook chamber opening says it should be 159.4 in^2 but it is the top half of the round firebox overlapping the bottom half of the smoking chamber to it looks like a cat's eye turned sideways and I don't know a calculation for this area. It is 15.5" x maybe 8" square but subtract half of a 4" x 4" corner or 8 in^2 from each of the four corners. That is 124 in^2 - 4*(8 in^2) = 92 in^2. I don't know that this is right as it could be higher. Still, the numbers are not too far off the ratio calculator.

Hope that helps.

I skipped Row 14 as this was a "0" value for my round firebox. My exhaust chimney should have a volume of 160.31 (that looks like 5% of the firebox volume) and then it asks for the diameter of the chimney and mine is 3" and this notes that the length of the chimney should be 22.69" but it is actually around 14" though I'm not sure what the importance of this being 22" is (maybe to get the smoke above your face so it doesn't blow into your eyes?). If mine were another 8" higher it would be aggravating to reach up six and a half feet to keep adjusting the vents (and my wife wouldn't be able to reach it).

For the air inlet opening it is a bit more math for me and it is late. Mine is a typical round opening with 2 pie pieces missing out of 4 pie pieces and the air inlet damper can fully cover or uncover the openings. The total air inlet is about 8" diameter and Pi*r^2 gives me 50.27 in^2 but half of that is permanently closed so only 25.13 in^2 max with the middle 2" diameter taken by the mounting of the damper (or 1.57 in^2) so that gives me about 23.5 in ^2 though the sheet doesn't allow for that so I hand-entered the number into cell F25.

The Firebox to cook chamber opening says it should be 159.4 in^2 but it is the top half of the round firebox overlapping the bottom half of the smoking chamber to it looks like a cat's eye turned sideways and I don't know a calculation for this area. It is 15.5" x maybe 8" square but subtract half of a 4" x 4" corner or 8 in^2 from each of the four corners. That is 124 in^2 - 4*(8 in^2) = 92 in^2. I don't know that this is right as it could be higher. Still, the numbers are not too far off the ratio calculator.

Hope that helps.

well said Darren..........

### #6

Posted 20 July 2009 - 10:13 PM

Thanks for the reinforcement. You can take the Engineer out of school but you can't take the school out of the Engineer? Dad is a retired Chem E. from Bayer, brother is a Professional Chem E./Industrial E. at Citgo, I ended up dabbling in Mechanical Engineering Technology and Plastics Engineering Technology in college but the first job out of college looking over drawings for quoting bids and projects. Heh, oops. That migrated into a Computer Technician role, more Computer Tech roles, and I'm now full-time as an IT Support guy. Still love the Engineering side of things though and all shows on Modern Marvels, How It's Made, etc.

Yoder Smokers (circa 2009) Cheyenne model w/convection plate - charcoal smoker/grill with side firebox (375 lbs and made from 1/4" plate)

Nexgrill (circa 2009) #720-0649 model - 3 main burners, 1 sear burner, 1 rear burner gas grill with rotisserie kit

Terra Cotta (circa 2006) - home-assembled smoker (soon to be dismantled)

Sunbeam (circa early 1990s) - 2 burner gas grill (soon to be discarded)

Habachi (circa late-1970s) - charcoal (soon to be discarded)

Nexgrill (circa 2009) #720-0649 model - 3 main burners, 1 sear burner, 1 rear burner gas grill with rotisserie kit

Terra Cotta (circa 2006) - home-assembled smoker (soon to be dismantled)

Sunbeam (circa early 1990s) - 2 burner gas grill (soon to be discarded)

Habachi (circa late-1970s) - charcoal (soon to be discarded)

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