New 100 Gallon/400 Litre Reverse Flow Build Project

Discussion in 'Reverse Flow' started by toro10rojo, May 13, 2015.

  1. Hi all,

    Mentioned in my initial roll call post that I was aiming to get going on a reverse flow build project. Finally managed to secure a 100 gallon/400 litre (approx) compressor tank and so will be getting the build work started ASAP!

    Full disclosure; I don't have the welding/metal work skills to actually build it myself and so figured rather than be foolish, best to work with a local fabricator to get this done! I'm doing the design/spec and than will pay a pro for the hard work!

    I'm still working on my design so at this point, I would be grateful for people's input and guidance/advice.

    This is the tank:

    1/4" thick all over. Lengthways, it measures about 67" - 60" weld to weld - and then around an additional 3.5" at each of the capped ends. 

    Diameter is approx. 20 inches. (I'm noting most measures as approx. as I have had the numbers given to me by the supplier/fabricators but I want to measure myself when I visit the yard tomorrow, before I start talking absolutes.)

    For now, I will use the measures I have in order to be able to check on my workings (if I measue tomorrow and there is any difference, I can amend there and then.

    As it stands, based on 67" length and 20" diameter - adjusting for loss of 1/4" due to thickness shell:

    Capacity: 19,375

    FB/CC opening: 78.3

    Going for a larger FB than required by the calc- 10,648 vs. 6457.9. Will be 22x22x22in, with an additional 4in below the bottom (6in below the grate) for ash dump. Will be 1/4in steel all round and will likely insulate.

    Air inlets: 21in total (slightly over the 19.6 calculation but makes it easer to measure) Will be split as follows: 4x3in inlets at/just below grate level, 3x3in inlets opposite the FB/CC opening.

    RF plate will be 18" length 60.375 inches length by 18in" width.

    Will be going for two doors; 26in length, cut at half way and at the 80° degree mark. Will leave 2 inches at either end from the weld line, with a 2in strip in the middle.

    That's where I'm up to so far, essentially what I need to get the work underway- doors cut, steel for FB ordered, FB assembled and fitted, RF plate ordered and fitted.

    I would be grateful for any number/calculation checking if anybody's up for it. Off to sit down with my fabricator/welding guy tomorrow and will take some final measures before finalising plans. Once I get underway, I plan to be checking in on the build pretty frequently so will try to take and post pics/updates as it comes along.

    And before I forget, shout to Boomhower; the final product I am shooting for was very much influenced by his own 100 Gallon build. Also DaveOMak, Ribwizzard, LenDecaturAL, Gary S and anybody else who gave great advice/answers to other peoples questions that I just stole information from! :)

    Thanks all!

  2. lendecatural

    lendecatural Smoking Fanatic

    Pinching free information doesn't count as stealing!

    Long skinny tanks don't flow especially well but we'll run the numbers and post up results.
  3. lendecatural

    lendecatural Smoking Fanatic

    The numbers are spot on, use a 4" pipe 30" long for the exhaust and you are good to go. I would recommend insulation in your climate and one of us will be over for a pint when you get it completed. 
  4. tykenn28

    tykenn28 Fire Starter

    I love watching smoker builds. Post lots of pictures
  5. Thanks Len, appreciate the confirmation.

    Would have liked the tank the have a slightly larger diameter but found it to be slim pickings re. used tanks over here. Beggars can't be choosers!

    Sit down with the fabricators today was productive. Talked through the first stages of the build- doors, constructing/mounting the firebox and the RF plate. Ordered the steel for the firebox and RF plate, will come in next week and then will be back down to sign off before he begins welding.

    Decided to go with 1/4" mild steel for the RF plate with a removable 2mm stainless steel layer on top. Will be split into two sections so it's easier to take out and will have a lip to essential function as a drip/water tray.

    So whilst phase 1 gets underway, time to find chimney!
  6. Re. burning out the tank and shot-blasting, looking at other build projects it would seem some people do this before they begin welding in the RF plate, rack rails etc and some do it afterwards.

    I have a local firm that will do the shot-blasting and power coating for me but I guess my questions is, it preferred to both burn out and blast as early on in a build as possible?

  7. bgingras

    bgingras Fire Starter

    Is the powder coating heat resistant? I was able to rapidly strip to bare metal with my angle grinder and a knotted cup brush. This was done partially before starting and the rest upon completion. It kept the metal protected from rust in the areas I didn't weld.
  8. Update: been a couple of weeks since I sat down with my fabrication/welding guy, talked design and ordered the steel for the firebox and RF plate.

    Steel finally came in, build is now underway and my guy sent me this pic of the FB tacked together next to the tank. (I have asked him to double check the assembly as I want the open side - door side - opposite the FB/CC opening.)

    FB is big but I went for a slightly oversized box anyway and there is also an extra 4 " at the bottom for an ash tray.

  9. smokejumper

    smokejumper Smoking Fanatic


    Maybe it is just a bad angle of the photo, or I am not seeing it correctly, but....

    It sure looks like the open side of the FB is not opposite the FB/CC opening.

    Just sayin'.

  10. Don't work SmokeJumper- you're not seeing things! The opening is on the wrong side in that pic hence me saying I want him to check the box assembly. It's only tacked together in the pic, hasn't been welded yet. I'm hoping he's just thrown it together for the picture to give me a sense of size/scale. Otherwise he will definitely have cut some of the steel to the wrong size!
  11. More progress made at the back end of the week, my guy got the doors cut out and the FB/CC opening cut into the tank. Also picked up my chimney at a local metal yard, 4" internal diameter, 42" length in total (pics below)

    Working to finish rack design over the weekend - planning on a stainless square bar frame with stainless expanded mesh laid over. Should have the tank burnt out and shot-blasted soon - hopefully next week.  

  12. So, er, it's been a while!

    Wasn't sure on the etiquette here but figured if I am going to start posting again, the proper thing to do would be to wrap this one up!

    Had my smoker completed late in the summer of '15 and have been pretty pleased with it to date. Definitely made a few mistake with the design, namely the doors/hinges (leaked like a b*itch and sealing the doors has been a real issue) but in general, runs pretty well- good draft, holds temp well, pretty even side to side.

    A protracted house move that started in late '15 (don't ask!) meant that I didn't actually get much run over the first 18 months (maybe 4-5 cooks) but I resolved to start doing a lot more this year and so far am averaging 2-3 cooks a month. Started off initially using a charcoal basket filled with briquettes - a sort of minion method attempt - but have since found a local wood supplier and this year have started running on wood only, primarily oak. Typically start with couple chimneys of lump and then splits only rest of the way. 

    Anyway, a belated thank you to all those whose previous builds threads, advice posts and hints/tips help to shape the build. Updated pics of both the complete build and some of the resulting, um results below!

    shyzabrau likes this.
  13. smokejumper

    smokejumper Smoking Fanatic

    No worries on etiquette, post what you want when you want. I've been lax myself since getting mine done, but I still need to paint it so more posts to come.

    You smoker came out great and the Q-view is awesome. Likely the best food in the UK!

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