First RF smoker- 115 gal propane tank

Discussion in 'Reverse Flow' started by slowjeep, Jul 28, 2013.

  1. slowjeep

    slowjeep Fire Starter


    Hey SMF! I'm going to follow the common recipe for RF smokers and put a firebox on the lower right corner with a single door and two full length racks. I aim to smoke butts and small whole hogs.

    I picked up the tank above for 60 bucks off of craigslist and some weld on bullet hinges from online for 5$ each, shipped.

    I won't be doing anything revolutionary so I appreciate any an all feedback for those that follow along.

    I downloaded a spreadsheet for dimensions from the link on Boomhower's thread.

    I think I'm gonna do a spring assist door with some kind of over center mechanism.

    More to come!
     
  2. smokejumper

    smokejumper Smoking Fanatic

    Sounds like a good plan.

    Looking forward to pics of your build. [​IMG]
     
     
  3. slowjeep

    slowjeep Fire Starter

    Picked up 400 or so pounds of steel from the scrap yard yesterday.  At 30 cents a pound, it was a way better deal than buying from the steel store.  I also picked up a sheet of 3/4-9 expanded for 65 bucks.  Today I'm cutting all of the fittings off of my tank with my torch.  Pictures to follow.
     
  4. slowjeep

    slowjeep Fire Starter

    I have the legs and fittings cut off of the tank and now I'm working on getting patches cut for the holes I've made. The tank appears to be 3/16" thick.

         

    This is a piece of 3/16" I scored at the scrap yard.  I don't know what it would have costs at the metal store but it was 30 cents a pound from the yard.  I'm gonna use it to make the firebox.


    Also picked up the galvanized pipe below for the chimney.  It is approx 1/16" wall and a little smaller on the ID than the 3.5" I was looking for but it'll have to be close enough.  I think it's 3.25".  The rusty pipe is for a different project.

     
  5. slowjeep

    slowjeep Fire Starter

    This is what I'm working towards.  

     

     

    I haven't figured out how to shut off the fire box supply to the cooking chamber while adding wood.  Think it is necessary?

    I didn't feel like modeling it but, I intend on the red tray to have a lip so that it'll hold water.  I envision a fill and a drain that are accessible from the outside. 
     
  6. slowjeep

    slowjeep Fire Starter

    All patched up.


    Next I'm gonna start cutting the door.
     
  7. slowjeep

    slowjeep Fire Starter

    Got the door cut out a few days ago.  I built a fire in it to burn out the petroleum smell and an added benefit was the paint flaking off. 



     
  8. radioguy

    radioguy Smoking Fanatic

    Jeep,

    So far so good.  IMO --You want to reconsider the use of galvanized pipe.  It gives off nasties when heated.  It don't weld too well either. 

    Looking forward to your build.

    RG
     
  9. bruno994

    bruno994 Master of the Pit

    I agree with RadioGuy, you might want to skip the galvanized pipe as your exhaust, although I don't think as your exhaust you will have any problems as far as the nasties, but you will have a tougher time welding it. 

    As far as a shut off between the firebox and chamber when adding wood, totally not necessary.

    A lip and a drain on your RF plate is a must, especially if your planning on using water in it while cooking (I don't, but to each his own), this also makes cleaning your pit out a snap.  After cooking on mine, I simply pull out the grates, scrape off any heavy fat deposits, build a small fire, then hit it with a water hose a few times, drain the grease and water into a bucket to get her spic and span clean and ready to cook on again.  
     
  10. slowjeep

    slowjeep Fire Starter

    Thanks for the input guys.  I was thinking that if I made sure not to inhale the vapors from welding I'd eliminate my risks since it's on the exhaust and not in the cooking chamber per se.  Perhaps I'll swing back by the scrap yard and see if I can pick up something better.  I was actually hoping to sink the chimney tube down into the cooking chamber a foot or so.  The intent being to keep down the overall height of the cooker.  I doubt the chamber gets hot enough to vaporize the zinc but there's no point in being bull headed over a matter like this.
     
  11. slowjeep

    slowjeep Fire Starter


    I cut up that sheet and welded it into a box. I noticed that it is 1/4" not 3/16". This grill is gonna be heavy. I used the spreadsheet to come up with a 25"x24"x18".

    I still haven't nailed down the inlet design or the door.
     
  12. maple sticks

    maple sticks Smoking Fanatic

    " I was actually hoping to sink the chimney tube down into the cooking chamber a foot or so.  The intent being to keep down the overall height of the cooker."

    If your counting the length of the chimney inside the cooker as part of your needed chimney height I'm not sure it works that way. Chimney height starts at the top of the smoker.
     
  13. slowjeep

    slowjeep Fire Starter

    Hmm.  Does anyone know the purpose of the chimney and why length matters?  I assumed the effectiveness of whatever it does was a function of length and diameter.  Perhaps density of the exhaust gas has some effect too. .Thus, it wouldn't matter if the chimney was sunken into the cooker.  Thoughts?
     
    Last edited: Sep 4, 2013
  14. slowjeep

    slowjeep Fire Starter

    Alright, I did some homework on chimneys. Thank you for setting me straight Maple Sticks. I was envisioning a different mechanism and was wrong. The difference in height between the inlet and chimney top seem to be what matter not the length of the chimney per se. Thus, I won't sink it into the cooker for that reason.
     
  15. Here is a website that is approved by SMF  this will give you the dimensions on everything. The chimney does need to be a certain length the corresponds to the size of the cook chamber as well as the fire box.

     http://www.feldoncentral.com/bbqcalculator.html

    Gary
     
  16. Looks like a nice size smoker,  I to would 86 the galv. Stack   and see if you can't come up with some reg. pipe.

    Gary
     
  17. slowjeep

    slowjeep Fire Starter

    Tonight I started removing the zinc coating on the fire box.  I'm using muriatic acid and it is a slow and stinky process.  When I hit the power ball I won't have to buy coated metal from the scrap yard and it's gonna be sweet.
     
  18. Do some research on the galvanize., zinc and chemicals you are using, You sure don't want to spend the time on you build to find out that your BBQ tastes funny or makes you sick.

    Gary
     
  19. slowjeep

    slowjeep Fire Starter

    The HCl is stripping the zinc off and now the steel is rusting. I'll build a hot fire in the box bf I weld it in to volatilize off any remaining funk.
     
  20. Sounds like a plan 

    Gary
     

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