325 Gal Reverse flow

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thecapps

Smoke Blower
Original poster
Aug 17, 2011
81
16
Suffolk, Virginia
Hello everyone, I have been wanting to do this build for quite some time now, Just today I obtained the most important part of the build, and I am super excited now.  What I have to work with is a 325 gallon Propane tank that was built in 1955, It measures 41 inches in diameter and is 73 inches in length.  The greatest part is the thickness, the plate reads that the shell which is the cylindrical part of the tank is .343 (11/32) way thicker than I had expected, The Heads .2301.  This thing is heavy duty.  My Idea is to make it a trailer mounted smoker to pull behind my truck.  I have been gathering some ideas over the years from some commercial built ones bubba grills and Horizon smokers, so I may borrow some of the ideas.  I would like to have a vertical box above the firebox as I saw on a bubba grill model, it held like 6 of those foil pans or I think they call it a rib box too.  Well now that I got this tank I can plan from here, stay tuned, I hope to be smoking in the near future.  Any advise from anyone that has cut into a propane tank would be greatly appreciated.  I have read the idea about filling the tank with water, I though maybe evacuating the tank with a vacumme pump.


 
Well I got the tank full of soap and water yesterday. I have come up with a name for this build "One man's trash..." So far a have no money in it. A guy at work changed one of the axles on his car trailer and put heavier springs in when he replaced the axle. So I grabbed the axle and springs out of the steel bin and I am going to use them. I had to straiten the axle a bit it's now "close enough for government work" as I say. I cut the spindles off because the axel is going to be shortened anyway. I will have to buy some stuff, I need new bushings and hardware for the springs and some new u bolts and new bearings. For a trailer I have a boat trailer that was given to me. I am going to make it a tandem axle trailer, using the axel that already on the trailer as the other axel. I will also probably be buying a sheet of 1/4 plate and some expanded metal. Well I'll be working on it in some free time so stay tuned.
 
is there a maximum size for a firebox? My calculations have my firebox at around 14 cubic foot. That is pretty large, what kind of fire am I going to have to maintain to make the 325 gallon tank work? I think I am scratching the idea of the rib box and just going with a firebox alone.
 
Gonna be a massive smoker for sure.  Sliding racks or as Dave suggested, doors on both sides for much easier access with a width of 41".  If you have the $ to add the rib box, I would, it will come in quite handy.  I added mine about a year later, but I also added a slave plate in the top of my firebox to keep my temps in the box down around 200 or so.  I really wanted them to stay closer to 175, but I have made 200 work so far.  Build the firebox per the specs, you won't regret it.  Bigger is better than too small.
 
is there a maximum size for a firebox? My calculations have my firebox at around 14 cubic foot. That is pretty large, what kind of fire am I going to have to maintain to make the 325 gallon tank work? I think I am scratching the idea of the rib box and just going with a firebox alone.

14 cubic feet... The FB is recommended to be 1/3 or larger than the CC.... At 325 gallon... 1/3 = 108 gallons or 14.48 cubic feet... Sounds like you know math.... you are spot on....
 
What is a good height for a firebox? Kind of limited when mounted to a trailer unless I jack the cc up mounted high on the trailer. My scratch dimensions are 24 deep by 30 wide by 36 tall giving me 25920 cubic inches.
 
How wide is the tank at the cut? (your chord dimension and RF plate) That is a short fat tank so it will flow air well, your 36" will be fine, but you need to match the width to the RF plate. 

It really is a heavy tank, should rust out by 2075.....
 
The width at the cut is 38". I hope it last at least till 2075.... So the firebox isgoing to be wider than 30" as figured up before.
 
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I had to bring it home and work on it. My uncle was too freaked out that the tank was going to explode on me. I'm still alive! He gave me a "do you believe everything you read on the Internet?" Speach.
Priceless!!!  
ROTF.gif
 
Lol we're cutting into our tank this weekend and I've gotten the same talk from several people. lol
 
The funniest part was he wanted me to throw it in our Scrap steel bin. I told him I'll take it back home before I throw it away. Took me long enough to obtain this Tank I'm not gonna let it go that easy.
 
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You already did the scary part... once the first cut is done, the only danger is from welding burns or dropping something on your foot! Of course, I almost never get out of the garage without drawing some blood....
 
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