My 100 gallon propane tank smoker build

  • Some of the links on this forum allow SMF, at no cost to you, to earn a small commission when you click through and make a purchase. Let me know if you have any questions about this.
SMF is reader-supported. When you buy through links on our site, we may earn an affiliate commission.

jmud

Meat Mopper
Original poster
Jan 28, 2013
193
15
Elba NY
My first thread on here, excited.  Almost bought a smokey mountain till i remembered i had a welder and half a brain to building things.  I bought a 100 gallon tank for $25 and will be getting a 4 by 8 trailer frame for $50.  Not a bad start I dont think.  I've been doing a little bit of reading here and there and got some ideas together and here is what I got for ideas:

1 single door to access cooking area

A single grate to cook on (should i think about a spit also???)

20" square firebox

4'' chimney at 32'' long (and thinking about a bull horn tip like you see now and again on semi trucks)

25 sq inch air inlet

13'' diameter half moon opening between firebox and cooking chamber

tool platform/table in front of and possibly side of door

box mounted on front of trailer for wood and charcoal

a couple cases of beer

tunes

time

Along the way I got a few ideas as far as air dampners, handles and such.  Firebox will have a basket on top of rebar and ash pan under rebar.  I got basic knowedge of building things, mostly carpentry stuff (its my job), but have basic welding knowledge.  Any ideas you might have I would greatly appreciate.  What experiences did you first have building a smoker for the first time?
 
Oh almost forgot. Thinkin about a warming chamber. Maybe attached above the fire box or something? What are your thoughts on that??
 
If you plan on using the warming box for smoking too, add that volume when you calculate everything. Your numbers look good for the tank at 100 gallons. I am working on a build myself and so far it is fun. Good luck and have fun.
 
Welcome to SMF!

Sounds like you have a plan. As mentioned if you plan on the warmer being used as a cooker as well that space needs to be factored into the firebox size. If you have not already done so take a look at the many builds that are on here and you will get tons of ideas and information. There are lots of very skilled craftsmen on here and they will be able to assist in many ways. Ribwizzard just posted a great post on triming the doors (Click HERE) or making the flanges.....

I am still in the frustrating stage of tons of ideas and plenty of access to equiptment, but due to unforseen issues the money is not there to get the metal to get started. I was going to do a similar build to Ribwizzards large smoker, but now I am waiting on another tank that will be cheaper in the long run....

Good luck and don't forget the Q-View pics along the way....
 
Welcome, sounds like a great upcoming build.  TONS of help available if you need it.  I'm excited to see the progress happen.

Good luck!
 
FB to CC opening

What is the diameter of our tank ???    Use the circle calculator below for your specific diameter.... 

Click on( O  Radius and Segment Height) adjust segment height ( D ) until the "segment area" = 64" sq. inches... 

That will give a number based on your specific tank design.....  

The reason I recommend this route.... I do not know where they get the "half moon" diameter numbers and how they could know the diameter of your tank....   

Dave

examples: 16"D ++  8 r and 5.7 seg. height = 64.2 sq in.

                20"D ++ 10 r and  5.2 seg. height =  64.9 sq. in.  

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

The RF Plate

Once you have that number, I recommend the area under the RF plate to be 1.5X the area of the FB to CC opening.... Use the same calculator to figure that number....  The increased area is designed to reduce friction loss in air/smoke flow under the  plate... and the opening at the end of the RF plate should be the same or larger area (96 sq. in.) because the air/smoke has to take a 90 degree turn at that point....  Those considerations will make your smoker the best it can be....  IMHO...    Dave

Example:  20"D tank...  10 r and 6.9 seg. height = 96 sq. in.   

Set the RF plate 6.9 in. above the bottom of the tank.....
 
Last edited:
  • Like
Reactions: buggman
So, in other words, top of "half moon" should be 15 inches and a total height in middle of it 4.5 inches equals 65........ I think that's what I'm getting from ya. Then I'm kinda lost after that ha, I got common sence but not so smart
 
Last edited:
Those  numbers depend totally on the diameter of your tank...    Did you run the calc with your tanks diameter ???  If I knew what the dia was, I would run the numbers...   Dave
 
Dave, am I correct that you are saying for the fb to CC opening to be the same radius as the CC x height to equal the area needed??  YES .... How important is it to be the same radius as the CC?
It is not important to be the same radius.... But, it will lower the opening to match the tank radius and allow for more room for cooking grates etc...  If the radius is smaller, the opening will have to be taller to get the correct area for proper air flow....

Using the calculations, I would set the FB into the tank at the same height as the RF plate... the top of the FB becomes part of the RF plate.... Then the opening to the FB will be lowed to the point the calculation recommends.....

I threw this together.... Hope it makes sense.....   

...........click on drawing to enlarge.........

 
Last edited:
Those  numbers depend totally on the diameter of your tank...    Did you run the calc with your tanks diameter ???  If I knew what the dia was, I would run the numbers...   Dave
Yea Dave if you could help with that it would be great. I love learning and maybe by showing me it would help me to learn
Total height of tank is 42 inches and diameter is 95 inches for my 100 gallon tank
 
Oh shoot, I gave you circumference. Give me a bit and I can get the number. (I am polish btw). Ok got a circumference of 32"
 
Last edited:
Ok ok, 32 diameter is 16r and 4.3 segment height = 64.4 segment area. Think I got it. 16 r and 5.7 segment height givese 5.7 inches above bottom of tank for rf plate. Think this is right?
 
Also updated for warming box:
Two: 25" square fire box and warming box stacked on top each other
100 gallon tank
5" by 40" chimney OR 6" by 28"
4-4" inlets
125 sq inch fb-cc opening (or make slightly larger than previously planned above, like 5"?)

Glad I'm taking time first to plan first
 
 
jmud, evening.....  The circumference is the distance around the tank....  

if the circumference is 95 inches, then the C = 95 / 3.14159  =  30.2 and r = 15.1 

Then assuming the wall thickness is 1/4".... then the inside diameter is 29.7".....  

We need some real numbers that are accurately measured to get this going.... 

Circ = 3.14159 x Diam..( distance across the circle)   r ( 1/2 the distance across the circle) = 1/2 D

Take a string and run it around the tank, then measure the length of the string that was in contact with the tank... that will be the "outside" circumference.... then we will figure the inside circumference and other valuable numbers.....  and help you build the best smoker in your town....   I hope Elba doesn't have too many folks that build smokers....  LOL....                    
 
Sorry I was unaware it had to be the inside diameter, that was never specified. 29.7 it is
 
Sorry I was unaware it had to be the inside diameter, that was never specified. 29.7 it is
 
Well, that was my fault.... Now that you are getting close to building, I wanted to get you close with the numbers.... All of the numbers used in the calculation are based on "inside" dimensions... CC, FB, Exhaust stack etc..... all are ID....  

The drawing below is with the larger FB... All the dimensions are based on the smaller FB because the exhaust does not flow through the warming chamber....  

I am of the opinion, having the exhaust flow through the WC will alter the heat control of the CC...  Having a CC with very good heat control is the primary goal...   

Here is how I would build it...

                                          ........click on drawing to enlarge.......

               
 
SmokingMeatForums.com is reader supported and as an Amazon Associate, we may earn commissions from qualifying purchases.

Latest posts

Hot Threads

Clicky