Cast Core HELP . Perlite : refractory cement ratio and math help!

Who is good at math? I want to figure out how many liters by volume my "tub" core mould will hold? Then I can figure out 60-70% of that is how much perlite I need, in liters, which is how the perlite is measured and bought, by the liter , by volume.

My core is 16" x 32" x 20"
That's 10,240 cubic inches?

My burn chamber is 20" x 6" x 6" = 720 cubic inches

My feed chamber is 6x6x9" = 324 cubic inches

My riser is (Pi) 3.14 x (Radius) 6" x (length) 14"= 263.76 cubic inches?
My core mix volume does not include the feed or burn chamber or riser, so I will subtract them from the total tub volume 720+324+263.7= 1307.7

How many liters fits into 10240 -1307.7 = 8932.3 cubic inches?

I feel confident that my math is good, EXCEPT for the riser, I'm sure that my math there is wrong.

Any input or help from any math whiz? I'm trying to figure out how many liters of perlite makes 65% of my core volume...

1 square =1" on my diagrams

I will mark this thread as RESOLVED after I get some help , thanks in advance, anyone with good math or casting experience

"My riser is (Pi) 3.14 x (Radius) 6" x (length) 14"= 263.76 cubic inches? "

6" diameter, 3" radius.
Area is pi x r squared, 3.14 x 3" x 3" = 28.27 x 14" = 396 cubic inches.
10,240 - 720 - 324 - 396 = 8800 cubic inches = 144 liters.

( http://www.metric-conversions.org/volume/cubic-inches-to-liters.htm?val=8800 )


And 144 liters is (off the top of my head) around 35 gallons, for a sanity check.

If I remember right I got 146 liters but what's 2 liters. Let us know how it turns out

thanks a ton guys . i knew my riser math was off.

8800 cubic inches = 144 liters

so i guess thats my total volume - and that means im going to require aLOT more perlite lol.

if i use 65% perlite by volume in my refractory core, thats about 93.6 liters of perlite ?!?

im going to need much more perlite evidently because i only have about a quarter of that much lol. i bought the last big bag i could find locally~

as soon as i can get temperatures above freezing and more perlite- im going to cast this thing!

correct me, if i am wrong. you want to calculate the volume of the heat riser?

it is hollow. so you need to calculate a soldid column (height X area) and substract the hollow interior.

I assume that your heat riser is 14 inch wide with a wall thickness of 4 inches.

so the base area is: 14/2^2*pi - 6/2^2*pi =153,86 - 28,26 = 125,6 square inch

multiply that by the lenght of that round heat riser and you ll have the volume of the needed material for the riser.

the riser will be cast separately from the core. but the riser will be 6" inside diameter and 8-10" outer diameter with a permenant outer mould form also. the riser should be easy i just want to know if my 65% perlite math is correct and i will focus on this core first.

14" is my thin grease barrel bell outer diameter, and those smaller barrels are about 26" tall, so my cast rise will in turn be about 24" long, exactly 2ft from the top of my core, will be the top of my riser. But there is also 14" of vertical riser built into the core itself. There will be a small volume of the same ingredients going into the cast riser, but the volume there will be only a fraction of this massive cast core volume