# Inkjunkies 60 gallon compressor tank RF build....

Discussion in 'Reverse Flow' started by inkjunkie, Jun 21, 2015.

1. ### inkjunkieMaster of the Pit

No more questions threads...spent the past hour or so with several tabs open on my laptop doing the math for this...

Been using the calculator that can be found here....

I have not cut my tank open so I am assuming, at least for right now that it is constructed from 1/8" steel. This may be a mistake but it is what it is...I measured the circumference of it and came up with 63.5", according to several on line calculators I have used

http://www.csgnetwork.com/picalc2.html

this puts the diameter at 20.21", which I will just call 20.25". This info will be needed when I get to the "circle calculator" stage of this nightmare.

Anyhow, I came up with a cooking chamber (cc) volume of 13860 cubic inches.

Using this number to figure out the size of the cutout between the firebox (fb) and cc I came up with 55.44 cubic inches....this will need to be known when I get to the "circle calculator"....

The area under the RF plate is also 55.44 cubic inches. This translates to the RF plate being tied into the top of the port between the fb/cc.

The area needed at the far end of the RF plate is also 55.44 cubic inches. Not real sure how this will be figured out. I have read that the RF plate needs to have a slight drop to it compared to the fb end. How much of a drop is necessary? How far from the dome to I end the RF plate? Math and I are far from best friends so....

If any of the above is incorrect please do point out my errors...

This seems like a logical point for me to end this post.....

Last edited: Jun 21, 2015
2. ### inkjunkieMaster of the Pit

Firebox...planning on insulating it...but I am going to build it first and then insulate as sort of an after thought...far to complicated for me to do it any other way. Came up with a minimum volume of 4573.8 cubic inches. Seeing as how the fb should be the same width as the RF plate I figured  --" for a width...on the outside. Have been told that any area under the fire grate is not included in the calculations...which means that the volume of the planned ash pan is not included. I plugged ----" for the width and --" for a depth and height into my calculator and came up with ---- square inches. This ends up being ---- of the minimum volume. This will be the internal measurements...so when I fire up the plasma cutter the plate/welder the external size of the box will be ----------------. Sadly this means some of the cord+ of cherry/maple fire wood will need some "trimming" done, I will just toss the odd short pieces into my Big Green Egg.

The vents for the firebox. I was informed by DaveOmak that I should figure on splitting the vents, --- of the volume should be at fire level with the remaining --- being inline with the fb/cc port. I came up with a air intake volume of ----- cubic inches.This mean I need ----- square inches of an opening at fire level and ---- square inches at the fb/cc port. Going to just round these numbers up.  In an attempt to keep things simple I am planning on just a simple rectangular slot for a vent...with a sliding door as a cover/limiter. A simple ----- slot at fire level and a ----- slot in line with the fb/cc port.

If any of the above is incorrect please do point out my errors...not that anyone will notice but I made a mistake here. I did the math for the fb prior to cutting the fc/cc port....

This seems like a logical point for me to end this post.....

Last edited: Jun 22, 2015
3. ### inkjunkieMaster of the Pit

Exhaust....I picked up a piece of 4" ID pipe....38" long....CC volume (13860) x .022=ESV in cubic inches...304.92....

ESV (cubic inches)/.7854 x4 x4.....304.92/12.5664=24.26

Exhaust has to be 24.62" above the cooking chamber. So the exhaust has to extend 24.62" above the exterior of the CC, correct? So anything that is below the exterior of the CC is not included in this measurement? I may use the "alternate stack". If I di how close to the cooking grate should I drop it.? I read someplace that if the exhaust stack is dropped to the grate holes should be drilled in the section inside of the CC so that the smoke can escape...is this correct?

4. ### boykjoSausage makerStaff MemberModeratorGroup LeadOTBS Member

Good luck with the build........Will be watching.        Don't forget "pictures"!

5. ### inkjunkieMaster of the Pit

Really hoping to get some confirmation that my numbers are correct so far....and my questions answered...

6. ### inkjunkieMaster of the Pit

Mistake #1, not realizing that the fb/cc port is not going to be in the middle of the tank. Firebox width is 17.5, not 19.5...glad I did not cut anything....

7. ### inkjunkieMaster of the Pit

And here comes my problem rearing its ugly head....the inability to "see" 1 step ahead...trying to figure out the firebox panels....hmmm.....need to figure out how to get that 400+ pound plate of steel up my table so I can lay things out, may make more sense....

9. ### lendecaturalSmoking Fanatic

Slope of the RF plate can be done inside the cooker or set the firebox up on a half inch piece of plywood or make it higher . Doesn't take much to make it drain.n

With your firebox more narrow, will that mean you can make it deeper to fit your wood?

The chimney should be measured above the top of the cook chamber. I would use the plenum style so you can make your cooking surface wider. You should have some plate scraps left to make the plenum and you won't have to cut the odd shape in the dome end of the CC. Its easier to work with a square piece of pipe.

I ended up getting some knee pads to deal with the heavy pieces on the ground. Its just a pain either way. It gets worse once you start getting the firebox together, they get heavy fast!!

11. ### locovetFire Starter

I made the mistake of going with the mid tank measurement for my firebox. So mine sticks out about an 1 1/2 on both sides of my cc. Doesn't look bad. I don't think anyone will even notice.

12. ### lendecaturalSmoking Fanatic

Ha! I beat you by two minutes with the crickets!!

13. ### mad dartSmoke Blower

I like variations.... Steps etc in things. Typical straight stuff us boring. My FB is wider than the cut out in the tank as well. Gives it more character!

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