Any other 320 gallon smokers out there?

john_az · Post by **john_az** » February 2nd, 2021, 3:38 am

I tried my best to search for other 320 gallon propane smokers, but cant find anything. Is there a reason for that?

30" diam, just under 10 feet long....seems like a great size to me. Any idea why not many builds with this size?

I just bought one off craigslist, never built a smoker from a propane tank before, so I was just curious if anyone else had any luck with this size.

I ran the numbers through the fancy pit calculator, which seemed to give me reasonable numbers for this size tank.

Any reason why I should not build this one?

Thanks!!!

dacolson · Post by **dacolson** » February 2nd, 2021, 8:58 am

Not that I've seen. Lots of 250s and 500s so I'm guessing it's just an uncommon size. Are you catering or using this for a restaurant? That's a big smoker.

Dirtytires · Post by **Dirtytires** » February 2nd, 2021, 10:04 am

Smoker sizes are infinite. Just because someone has not built one exactly that size is no indication that it is/is not a good size to build. Some of the more common sizes have plans available but the calculator is used to design them and will work equally well for yours. Follow the numbers as you design it and feel free to post your ideas and questions as you go.

Good luck!

john_az · Post by **john_az** » February 2nd, 2021, 1:43 pm

Well then 320 gallons of fun it is!

These are the numbers the calculator gave me.... I will follow them the best I can. Hope they look good to you guys. I have read some people tweak the numbers a bit for one reason or another, but since this is my first propane tank build, (I have built one pit before, but not from a propane tank) so I think I will just stick to the numbers.

Here is the tank, shes pretty heavy... fortunately that's a tilt trailer... so I might just pull the pin and watch her roll right off! haha

One question, whats the optimal height for a smokestack? I have heard if it is too tall, and the air cools and doesn't draw out very well.... should I find a larger diameter stack to reduce the height? or is 54 inches tall sound ok? I was planning on putting the stack at cook grate level.

thanks!

dacolson · Post by **dacolson** » February 2nd, 2021, 2:08 pm

Calcs look just fine. You could do 30x30x30 if it's easier on the FB but either is fine.
On the stack, 54" is from the top of the cooker. So whatever the length is from your grate level opening to the top of the tank, add that to the 54" to get your total stack height. That will be a tall stack if you consider the top of your tank will be in the ballpark of 50" or so. 8 1/2' is too tall for a garage so you may consider hinging it or else trying to find an 8" stack. Also, make sure you are using inside diameters of your tank and pipe. For example, a 6" schedule 20 pipe has a 1/4" wall thickness and ends up being is 5.5" ID.

mp4 · Post by **mp4** » February 2nd, 2021, 3:24 pm

Looks good. I concur with the stack height suggestion...size it large enough in diameter so it's short enough you can get it in (or out if you build it inside and expect to get it out) the garage.

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hogaboomer · Post by **hogaboomer** » February 2nd, 2021, 6:49 pm

dacolson wrote: ↑
February 2nd, 2021, 2:08 pm
Calcs look just fine. You could do 30x30x30 if it's easier on the FB but either is fine.
On the stack, 54" is from the top of the cooker. So whatever the length is from your grate level opening to the top of the tank, add that to the 54" to get your total stack height. That will be a tall stack if you consider the top of your tank will be in the ballpark of 50" or so. 8 1/2' is too tall for a garage so you may consider hinging it or else trying to find an 8" stack. Also, make sure you are using inside diameters of your tank and pipe. For example, a 6" schedule 20 pipe has a 1/4" wall thickness and ends up being is 5.5" ID.

Um... not really. For one thing, there is no Schedule 20 6 inch, you must be thinking Sch.40 or standard wall. The ID should be pretty close to 6. Close enough that it won't matter. The OD will be 6-5/8. The ID will be close to the pipe size, unless it's extra strong, or heavier wall. Pipe sizes change to OD measurements at 14 inch.

dacolson · Post by **dacolson** » February 2nd, 2021, 7:13 pm

hogaboomer wrote:
dacolson wrote: ↑
February 2nd, 2021, 2:08 pm
Calcs look just fine. You could do 30x30x30 if it's easier on the FB but either is fine.
On the stack, 54" is from the top of the cooker. So whatever the length is from your grate level opening to the top of the tank, add that to the 54" to get your total stack height. That will be a tall stack if you consider the top of your tank will be in the ballpark of 50" or so. 8 1/2' is too tall for a garage so you may consider hinging it or else trying to find an 8" stack. Also, make sure you are using inside diameters of your tank and pipe. For example, a 6" schedule 20 pipe has a 1/4" wall thickness and ends up being is 5.5" ID.
Um... not really. For one thing, there is no Schedule 20 6 inch, you must be thinking Sch.40 or standard wall. The ID should be pretty close to 6. Close enough that it won't matter. The OD will be 6-5/8. The ID will be close to the pipe size, unless it's extra strong, or heavier wall. Pipe sizes change to OD measurements at 14 inch.

I’ve got a length of 6” 3/8 wall at home. Just re measured. Thought it was 1/4”. Was told it’s sched 20 but I’m no pipe guy. Defer to you on that. ID is 5 1/4”. Point is to double check. It’s a big build. 3/4” difference smaller is almost a foot of extra pipe.

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john_az · Post by **john_az** » February 2nd, 2021, 7:38 pm

yikes, I had no idea the stack height is from the top of the cooker! yes, that will be way too tall... I will find a bigger ID stack, I might know where i can get some 8"diam thin wall stainless tube....

Im going to build a rotisserie to spin the tank around on to clean it, and hopefully cut the doors tonight.

updated calc. with 8in diam stack ( ID 7.875") so the stack calls for 26.875" tall + 15" (1/2 the diam of the tank to reach cook grate level) so roughly 42" from the top of the stack to cooking grate level... which is going to be at 36" from the ground, so overall height is 6.5 feet tall. Sounds great to me.

I just made my hinges for the doors.. rolled some 1 1/4" x 3/8" flat bar to fit the curvature of the tank, then notched them for the door flange/seal. If I can get the door cut tonight, ill weld them up and report back.

hogaboomer · Post by **hogaboomer** » February 2nd, 2021, 8:12 pm

8 inch will definitely be better for a smoker that big.

tinspark · Post by **tinspark** » February 2nd, 2021, 8:54 pm

john_az wrote: ↑
February 2nd, 2021, 7:38 pm
yikes, I had no idea the stack height is from the top of the cooker! yes, that will be way too tall... I will find a bigger ID stack, I might know where i can get some 8"diam thin wall stainless tube....

Im going to build a rotisserie to spin the tank around on to clean it, and hopefully cut the doors tonight.

updated calc. with 8in diam stack ( ID 7.875") so the stack calls for 26.875" tall + 15" (1/2 the diam of the tank to reach cook grate level) so roughly 42" from the top of the stack to cooking grate level... which is going to be at 36" from the ground, so overall height is 6.5 feet tall. Sounds great to me.

I just made my hinges for the doors.. rolled some 1 1/4" x 3/8" flat bar to fit the curvature of the tank, then notched them for the door flange/seal. If I can get the door cut tonight, ill weld them up and report back.
PXL_20210202_030741704.jpg
PXL_20210202_030726560.jpg

Square tubing works too if it is easier to find. I have seen a few guys turn them 45 degrees (like a diamond) and they look pretty cool.
Also, a few have made flip down stacks on a flange, hinge, pull pin and gasket, and stack receiver. depends on what u want to do..

john_az · Post by **john_az** » February 3rd, 2021, 2:45 pm

Awesome, thanks for the suggestions. I will go with the 8" diam stack... If I cant get this stainless tube, ill check out that hard to find "diamond shaped tube"

I got the doors cut, and hinges on... welded a temporary handle just to make sure the door moves freely. I will finish welding the hinges tonight, and get started on.... everything else!

It smells so bad, even after pressure washing the inside, and its not just the tank, the whole area around it is rough, the water that came out...very strong....?? any idea how long that lasts?

hogaboomer · Post by **hogaboomer** » February 3rd, 2021, 8:24 pm

Huh! I thought I was the only one that TIG welded smokers.

dacolson · Post by **dacolson** » February 3rd, 2021, 10:31 pm

Very cool looking hinges. Nice fabrication.
Man, I hear you on the smell. My wife was not impressed when I opened one on our driveway. Mostly gone after 3 or 4 days but it would pop up for a couple weeks ...

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Dirtytires · Post by **Dirtytires** » February 4th, 2021, 8:53 pm

You left room for the gasket before you welded the hinges on, right? If not, your door has a good chance of binding.

Also, if you already have the pipe for the stack, remember it is total cubic inches that matter. On that big of a pit, you would add a lot of character by putting two stacks side by side....

john_az · Post by **john_az** » February 11th, 2021, 9:01 pm

Dirtytires wrote: ↑
February 4th, 2021, 8:53 pm
You left room for the gasket before you welded the hinges on, right? If not, your door has a good chance of binding.

Also, if you already have the pipe for the stack, remember it is total cubic inches that matter. On that big of a pit, you would add a lot of character by putting two stacks side by side....

Actually thats a cool idea, never thought of multi-stacks! This sparked an idea.... I my pick your brain on it, but I have a ways to go until I'm ready for the stack....

john_az · Post by **john_az** » February 11th, 2021, 9:25 pm

I got a few small things done... the smell has been tough, the tank is stamped 1946.... so its had a long to let the stink soak in hahah... I have pressure washed it twice, did a burn... pressure washed it after the burn, it still smelled bad, so i climbed in the other night and went to town for hours with a wire wheel.... smell it better but it's still there... and not so appetizing. Can i scrub it with some Simple Green or something?

Heres a few pics of some slow progress.... and I have a few questions on the fire box.... that's next....

the tail end of the burn, went through a lot of wood that night hahah

I then clean it up again, and finally got it into the garage, when the real fun starts...

Made the lower cook grates, I wanted them to be removable for easier cleaning, and i really like how i can easily slide them left to right, the full length of the cooker... could even use those cooking grates to load briskets on, then carry out to smoker and just load the whole tray in or out to take food off..?? something to think about anyway...

Also, i used a clamp to pull the expanded metal super tight as I welded it in the frames.... SOOOO much better... its unreal how stiff the grate feels... the center might still sag.... but as of right now, it seriously feels like a solid steel top.. zero deflection... I guess im slow to the party on that idea hahah... also those fireball squares made quick work of jigging up the frames... love those things!

john_az · Post by **john_az** » February 11th, 2021, 9:33 pm

Tomorrow I going to build the firebox... but I have a question on the air inlets... the calc says i need 4 air inlets with an area of 84 in^2 (actual) and 82 in^2 (recommended)... do i just divide up the 82 in^2 into 4 inlets... those would be some huge air inlets...??
I read on here you should do 80% of the air inlets below the fire grate, and 20% above (to help move air into CC) it just seems to me that the inlets are way too big... Can I spread that 82 in^2 across more inlets to cut down on the overall size of each one? So maybe 4 in the door, and 4 on the right side, and 4 on the left side??

thanks for the advice!!!

dacolson · Post by **dacolson** » February 11th, 2021, 9:37 pm

Excellent work. Your fit up is fantastic. I like the square tubing with the flat stock frame on the inside of your grates. Very clean look. I’ve never seen the clamp used to tighten up the expanded. Great idea. Wish I’d seen it before.
Those grates loaded down with a few briskets will be HEAVY! Definitely make the grates removable like that for easy clean up but I’d wheel your meat out on a cart and load them straight in. Cool idea on making the rails so you can slide the grates left to right. Make sure you put grate stops on there to keep them from tipping out when you pull them out with meat on them.

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dacolson · Post by **dacolson** » February 11th, 2021, 10:09 pm

Hey John, I missed in your pic how you have the grates sitting down into the CC below the door openings. I’m guessing you wont be sliding loaded grates in and out so you can probably skip the grate stops.

Is the pit calculator calling for 4 x 84” inlets and is it telling you that you are at 100% recommended?

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Post by **Big T** » February 11th, 2021, 10:15 pm

I'm not sure if I'm understanding your question about the air inlets but you only need 82 sq inches total. I normally put 2 inlets, one on each side and they're both the recommended size so that I can close one off and use the other if the wind starts blowing directly into the inlet. You want to keep them as low as possible on the fire box so that the air can't bypass the coal bed.

john_az · Post by **john_az** » February 11th, 2021, 11:57 pm

dacolson wrote: ↑
February 11th, 2021, 10:09 pm
Hey John, I missed in your pic how you have the grates sitting down into the CC below the door openings. I’m guessing you wont be sliding loaded grates in and out so you can probably skip the grate stops.

Is the pit calculator calling for 4 x 84” inlets and is it telling you that you are at 100% recommended?

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Ya, no sliding out, I think the door opening is tall enough to make loading the grates easy, really just wanted to make them removable for easy cleaning of grates and inside bottom of tank...

Here is what the calc. said for air inlets, it says 4 with an area of 81in^2 recommended... not sure why it says 4 inlets if its just a total of 82 in^2 ....
(Im putting the smoke stack at grate level, so the +15" is just to i dont forget to add that to the stack length... Im glad someone told me that!!!! )

dacolson · Post by **dacolson** » February 12th, 2021, 12:13 am

I’m guessing you put in the measurements that the opening would be 1/4th of the 81 sq in required. You can play around with the size of your openings in the calculator to come up with better options. If that’s the recommended area, you could do two 4x10” openings - one on either side, for example. I have read that splitting your inlets 80/20 helps to add fresh oxygen in the top of the FB to further combust wood gases - improving smoke quality. I did my first pit that way. Not sure it matters. The next 3 are all vented below the grates and burn very well.

Big T’s comment on doubling the vent capacity - 82 sq in on both sides - is spot on. It gets windy here and I’m always closing one side or the other off.

john_az · Post by **john_az** » February 12th, 2021, 12:36 am

Big T wrote: ↑
February 11th, 2021, 10:15 pm
I'm not sure if I'm understanding your question about the air inlets but you only need 82 sq inches total. I normally put 2 inlets, one on each side and they're both the recommended size so that I can close one side off and use the other if the wind starts blowing directly into the inlet. You want to keep them as low as possible on the firebox so that the air can't bypass the coal bed.

Hey Big T! I was just confused about how i got that number of inlets... i just went back through the calc. and realized i can control that number by putting the size of one single air inlet. brain fart... sorry... i get it now... and Im totally going to do what you did, one fully recommended size inlet per side..... but what about the BF door.. can/ should i add one in the door to give a third option for inlet?

Also, what's your feeling on a few smaller upper intakes on the BF door... is the 80% below fire grate, and 20% above a good rule for that?

Thanks so much! im sitting here now drawing up the firebox, I ordered 2, 4x8 sheets of 3/8" steel for the FB, and they are showing up tomorrow.... I wanna try to get the whole firebox done this weekend, but I need to finalize the design.... so your help is awesome! thanks!
***(anyone else notice the price of steel recently...?? those two 3/8" plates were just under $875 bucks... yikes... but the guy told me its American made steel...so I like that...but Im not sure how you can tell?? maybe there is a "made in America" stamped into it somewhere hahahahah!!!??

john_az · Post by **john_az** » February 12th, 2021, 12:39 am

dacolson wrote: ↑
February 12th, 2021, 12:13 am
I’m guessing you put in the measurements that the opening would be 1/4th of the 81 sq in required. You can play around with the size of your openings in the calculator to come up with better options. If that’s the recommended area, you could do two 4x10” openings - one on either side, for example. I have read that splitting your inlets 80/20 helps to add fresh oxygen in the top of the FB to further combust wood gases - improving smoke quality. I did my first pit that way. Not sure it matters. The next 3 are all vented below the grates and burn very well.

Big T’s comment on doubling the vent capacity - 82 sq in on both sides - is spot on. It gets windy here and I’m always closing one side or the other off.

Awesome, makes sense now.....thanks so much for your super-fast response, honestly very helpful, and my material shows up tomorrow, and i just want to knock this out this weekend, so this really helps!

you will see your suggestions in steel within a few days! thanks!

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Any other 320 gallon smokers out there?

Any other 320 gallon smokers out there?

Re: Any other 320 gallon smokers out there?

Re: Any other 320 gallon smokers out there?

Re: Any other 320 gallon smokers out there?

Re: Any other 320 gallon smokers out there?

Re: Any other 320 gallon smokers out there?

Re: Any other 320 gallon smokers out there?

Re: Any other 320 gallon smokers out there?

Re: Any other 320 gallon smokers out there?

Re: Any other 320 gallon smokers out there?

Re: Any other 320 gallon smokers out there?

Re: Any other 320 gallon smokers out there?

Re: Any other 320 gallon smokers out there?

Re: Any other 320 gallon smokers out there?

Re: Any other 320 gallon smokers out there?

Re: Any other 320 gallon smokers out there?

Re: Any other 320 gallon smokers out there?

Re: Any other 320 gallon smokers out there?

Re: Any other 320 gallon smokers out there?

Re: Any other 320 gallon smokers out there?

Re: Any other 320 gallon smokers out there?

Re: Any other 320 gallon smokers out there?

Re: Any other 320 gallon smokers out there?

Re: Any other 320 gallon smokers out there?

Re: Any other 320 gallon smokers out there?