Measurement Question

[jabbo]

Since I have been unable to begin my build, I spend a lot of time planning.  I have spec'd it out in the calculator 100's of times.  There is one measurement that the calculator does not give and I was wondering if anyone could help me with it.  What is the distance from the RF plate to the bottom of the tank?  I know the Plate should be about 28 inches wide on a 500 gallon tank, but how much space would that leave me under it?  Now, so far, my calculations are showing it will be between 8 and 10 inches, but I'm not real confident in that.  I need to know this so I can figure out how much space will be left over for grates.  My build may get started sooner than I thought.  I have found a man who is willing to back my business start up.  He told me to get an accurate cost for him and that I might as well start with the twin tank trailer, as that is going to be the biggest cost and it doesn't cost any more to have them both, even if I don't use them both.  It's kind of like a condom.  It's better to have one and not need it, than to need one and not have it.  I am going to build twin 500's with matching hot grills in front of them.  I am currently looking for the right trailer and a good welder.  My dream rig will be a reality soon!

 

[jarjarchef]

I am sure one of the pros will chime in soon. The only thing I have seen is the RF plate from the bottom grate. And that was 4-6 inches. I would assume it would be a balance of that and the firebox opening need.

Are you planning a side fire box or a center fire box?

 

[jabbo]

I am putting the FB on the end in the traditional manner.  I know the opening width and once the tanks are cut I could easily measure the distance down.  I know it is a fixed height determined by the tank diameter and placement of the RF plate.  I also know that there are some guys on here who have built 500 gallon tanks.  I'm hoping one of them will take the measurement for me.  Of course, if I am correct, the ration should be the same regardless of the tank size.  So, if someone would be kind enough to measure the opening between the FB and CC, I would be very grateful.  I am planning traditional half moon style opening.

 

[jarjarchef]

Hey I am in for this one......

Just to help me picture this in my head. What is the deminsions of the tank? I have no need for one that big, but fun to play with in my head....:biggrin:

 

[bob1961]

the way i have my RF planned for the fire box to cook chamber is this....the 24" FB is square where the tank is 30" round....where i need to have the top FB plate is bout 7"....that will give me a 30" circle with a straight line as the top of my FB....what ever the square inches of that opening you have to remember the RF plate at the other end has to match the square inch the FB opening is....then the exhaust stack has to have the same square inch area....so the square inch area you need fro those connection between FB/cook chamber....that height of the RF plate will always be different for each smoker built....hope this wasn't confusing for anyone as bad of a headache it gave me thinking how to type that, lol.......bob

....

 

[jabbo]

Bob, I believe I understand what you are saying.  It sounds like you are saying that the distance from the RF plate to the bottom of the tank is 7 inches.  If that is the case, then my estimations were not far off.  The top of my opening will be 28 inches across.  So measuring from there down to the bottom of the tank should be 7-8 inches.  This measurement is not in any of the calculators I have found and really doesn't need to be.  I am just very meticulous in my planning.  Some say I'm even obsessive.   Thanks for that.

JarJar, the tank is 500 gallons.  It measures 10' long with a diameter of 37".  I will have 2 of them on the back end of a 20' trailer.  I will build a hot grill in front of each and place my sinks on the front.  It is still in the planning phase as I have yet to procure a vehicle to tow this behemoth.  But with my new financial backer pitching in, I am much closer than I was. 

 

[jabbo]

Well, it looks like good ol' Dave helped me and didn't even know it.  I was reading a previous build and found a post he made with a link to a circle calculator.  Between that and the build calculator I have been using, I was able to determine that the opening height needs to be 6.89" and the RF plate needs to be about 9" from the bottom of the tank.  Thank you, Dave.  

 

 

[daveomak]

Jabbo, morning.... Just found your thread.....  So, you have it figured ???  RF plate 1.5 times the square inches of the firebox opening to allow for friction loss ??  Same at the end of the RF plate ...   Any more questions, we are here.... PM's are always in order also...   My signature line has some cool links in it....  enjoy.....

Dave

 

[sqwib]

Interesting. Read.
My opening to the smoke chamber is the same exact size as the space underneath the reverse flow plate.
For 20" diameter tank its 4" from bottom of plate to bottom of reverse flow plate.

Mine works fine, however I would go by what Dave has said

 

[jabbo]

Yeah Squib, I think I will.  I honestly couldn't think how that whole friction loss caused heat loss, but I have read enough of Dave's posts to trust his judgement.  Besides that, it still left me plenty of room above it for grates and I didn't think it would hurt making it a little bigger.

Dave, I have it all figured now.  I even found that I have enough room for 4 grates if I do it right.  The only reason I didn't PM you is because I didn't know you had that link.  I figured one of you guys would chime in eventually.  Many thanks to you just the same though.

 

[bob1961]

that's what i was trying to say is that every smoker build will be different depending on what cubic inches you will
need for that opening from SFB to cook chamber....then it don't matter how high your RF plate is off tank bottom,
it can only be as low as your needed opening size has to have....then match the cubic inch with the end of the RF plate from end of tank.........bob

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[berry1611]

Hello Jabbo, check out the thread I started (First Build). Dave and others gave alot of good info.