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Reverse Flow smoker build need help including calculations

post #1 of 14
Thread Starter 

hey everyone, I'm a long time smoker, but only built UDS smokers up to this poing, and looking to build something on to the back of my trailer that I used for competitions.

 

Okay, so initially I have toyed around with just buying a Oklahoma Joe's smoker and cutting the legs down to mount it, but now I'm thinking I want to just build something not much bigger than an Oklahoma joes type deal, but with the features I want. So ive been looking for a smaller tank, like something in the 80-120 gallon range.

 

That being said, I have a person willing to give me this tank below, and wonder what you think of a possible idea. The tank is way too big for a standard build (I mean a standard build that I'm willing to do) so I'm thinking of doing something like a sketch I'm also attaching. basically picture a massive kettle grill, but with a fire box and a reverse flow set up. (not exactly sure how I can make the reverse flow work though)

 

Anyway, first of all do you think its a good idea and will be a good smoker, or do you think my idea will result in something kinda moody, and hard to run? Id probably put one large round grate in it at level when you open the dome, and then also put another shelf to take advantage of the dome area above grade level. I'm also worried this will be a lot more work than a more traditional reverse flow build, and ive never done one before either.

 

 

The tank is currently 5 ft 3 inches long and open on the other end. Its almost 3 foot in diameter

post #2 of 14

 

 

 

Here's some ideas you may want to think about.

post #3 of 14
Thread Starter 

That's a pretty cool way to do it, but ive got a few upright UDS ones currently so I'm looking to do an offset reverse flow for this build. Thanks for the reply!

 

Okay, so I had someone else reply to my tank search, and found what I think is the perfect tank, and went ahead and picked it up. This is an air compressor tank, and measures 47" long (36" weld to weld, and the domes are 5.5" from weld to end) and it is 64" in circumference, which I believe calculates to just over 20" in diameter. So this is my tank, and I could use some help calculating my firebox size. Ill pop in to the calculator after this too, but I already know I suck at math, so I could use a hand I'm sure.

 

What do you think?:

 

 

 

 

 

 

 

​ALSO AS A SIDE NOTE, IS ANYONE ELSE HAVING THE ISSUE ONB THIS FORUM LATELEY WHERE IT IS POSTING THE PICTURES (OR EMOJIS) AT THE TOP INSTEAD OF WHERE YOU HAVE YOUR CURSOR WHEN YOU UPLOAD? SUPER ANNOYING!

post #4 of 14
Thread Starter 

Ok, so as I mentioned before I am terrible at math, and could seriously use some help with the FB calculations. Ive run the calculators on the build (thanks so much @DaveOmak ) but I don't really know where to go from there. Here is what I have so far:

 

 

Dimentsions: 47" long, 20.38 in diameter. this s/b 15,331.94 CI in volume. The FB opening appears to need to be 61.32 CI. and my firebox needs to have a min volume of 5,059.54 CI.

 

I will go deeper into the openings and how to calculate that later, but right now I really just need to figure out how big to make my fire box (how to I calculate the dimensions out of the volume?, and how wide and long to make my exhaust pipe/pipes to start off.

 

Also are these just minimum dimensions so I can go a bit bigger if I need/want to (the reason I ask is it seems like the area below the tuning plate/RF plate will be to small based on these calculations since this isn't a really big tank.

​Any one interested in helping out with this?

post #5 of 14
Quote:
Originally Posted by Travisty View Post
 

Ok, so as I mentioned before I am terrible at math, and could seriously use some help with the FB calculations. Ive run the calculators on the build (thanks so much @DaveOmak ) but I don't really know where to go from there. Here is what I have so far:

 

 

Dimentsions: 47" long, 20.38 in diameter. this s/b 15,331.94 CI in volume. The FB opening appears to need to be 61.32 CI. and my firebox needs to have a min volume of 5,059.54 CI.

 

I will go deeper into the openings and how to calculate that later, but right now I really just need to figure out how big to make my fire box (how to I calculate the dimensions out of the volume?, and how wide and long to make my exhaust pipe/pipes to start off.

You want the FB at least as wide as theCC...  so... 20x20x16 = 6400 CI will do... tall enough to have room for ash under the grate and deep enough for wood...

Exhaust comes out ~ 26" above the CC using a 4" ID pipe..  To insure good air flow, I would build it at least 32" above the CC...

Also are these just minimum dimensions so I can go a bit bigger if I need/want to (the reason I ask is it seems like the area below the tuning plate/RF plate will be to small based on these calculations since this isn't a really big tank.
You can go bigger on all the numbers...  makes for good air flow...  Even 6" would be a good ED....
​Any one interested in helping out with this?

 

 

An ED dimension of 5.5" will return a segment area (green) of ~70 sq. in...  which will give a good air flow...  be sure to take into account the thickness of the tank and top of the FB when you make the cut out....  You can still go larger... anything larger be sure to follow through with the area under the RF plate and end of the RF plate...

 

post #6 of 14
Thread Starter 
Wow Dave! thanks so much for the info. Once I get farther into the project ill look for a bit more advice in that regard, but at the moment, I have a welder buddy (by profession) who is willing to get me a good deal on the steel and make me a fire box, so now I can get these dimensions over to him!

So I have a 5-8 trailer I currently use for competitions. originally I have been planning to just get an Oklahoma Joes and cut off the legs, but now ive got to revamp my plan to mount this smoker to the trailer! I also want to mount my two UDS smokers that I use for comps on the trailer too, so ill probably have to revamp my plans a bit on where to mount it all. I figure it wont be good to mount the smoker on the back of the trailer for weight purposes, and not wanting to pop the hitch off if a hit a big bump. The trailer I have has a goot thick axle, and has full sized tires on it, so I think ill be safe there. Any ideas or suggestions on layout.

Below is a scale sketch of what I was thinking with the UDS's and the Oklahoma joes. Now I'm thinkin maybe to mount the UDS's on the back, and the new build on the front and maybe put some folding RV stairs in on one of the sides? Otherwise, maybe ill just keep the UDS's in mounted, and just leave the ramp as is, and be able to pull them in and out like that but only have the new build mounted to the car side of the trailer... Thoughts?

post #7 of 14

Do the UDS's have to be ON the trailer...  can you set them off to the side... 

 

For the firebox, many folks on here have found the upper air inlet is a great benefit for temp control and reduction of fuel usage...

 

...

post #8 of 14
Thread Starter 

 

Quote:
Originally Posted by DaveOmak View Post
 

Do the UDS's have to be ON the trailer...  can you set them off to the side... 

 

For the firebox, many folks on here have found the upper air inlet is a great benefit for temp control and reduction of fuel usage...

 

...


​That was the plan. Saw this post from you on another thread, and was very helpful!

​The UDS's don't NEED to be on the trailer, so I may just wheel them in and out at each location. Just would be nice to have it all securely mounted for ease of use, and just to look more legit.  Its also possible I can mount, or secure them onto just one side of the trailer, and then as mentioned put the new reverse flow on the end, sorta like this: ( which I think will work, but this isn't 100% measured to scale)

 

though I don't know if having the smoker mounted that far forward will cause any issues with weight or the trailer fishtailing. This isn't THAT heavy of a tank, and the firebox isn't too big either ,so perhaps ill be fine.
 

post #9 of 14

Too much weight on the back end of the trailer causes fish tailing...   weight forward eliminates it...  

 

Well, if figuring out a floor plan for your smoking equipment is the biggest problem you have going, my friend, you are in hog heaven...  get a cold beer and a lawn chair, sit outside next to the trailer and envision all the possible choices and pick one....   LOL....

post #10 of 14
Quote:

Originally Posted by Travisty View Postthough I don't know if having the smoker mounted that far forward will cause any issues with weight or the trailer fishtailing. This isn't THAT heavy of a tank, and the firebox isn't too big either ,so perhaps ill be fine.

Ideally you want 10% to 15% of the GVW on the tongue. Things to consider when adding a lot of weight to the front are the vehicle hauling it. Will it cause the front end to lighten up? That is just as bad as too much weight on the rear. Another is mobility if not attached to a vehicle. Can the trailer be moved around with a wheel dolly if need be. The last may not be an issue for you just thought I would mention it.

 

post #11 of 14
Thread Starter 
Quote:
Originally Posted by kam59 View Post
 


​Thanks for the thoughts to consider! I think the vehicle should be fine especially since the smoker wont weight too much at its size. I may do it closer to center if I can. The bigger consideration Ill need to consider is moving it unattached as you mentioned.

 

Anyway guys, thank for the info, keep anything coming you guys think I should know or consider as I go. Ill keep updating the thread with pics and things as a go. Its gonna be a couple weeks before I get started cause I'm actually moving next weekend (having room to do this kinda stuff is a major reason for the move)

 

One quick question for all: What do you think would be a good BUDGET welder that should be able to do everything ill likely need to do for this build? Probably only have a couple hundred to spend at the most... (I'm also gonna keep a look out for some used ones, but assume I'm looking for something new for pricing)

post #12 of 14
If you're wanting a wire feed you're a bit light on funds. Stick welder you could get a low end with enough pop to do the project.
post #13 of 14
Thread Starter 
post #14 of 14
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