Surface area of an Spheroid Tank 3

[ChEGATOR]

I am looking for a formula that will allow me to calculate the surface area of an oblate spheroid tank. I have found formulas that will allow me to calculate the surface area of a spheroid, but my spheroid tank has a flat bottom, so I don't want to include that portion of the surface area. I would like to use the formula to calculate the wetted surface area of the vessel in an effort to generate a required relief rate for an external fire.

Thanks,

ChEGATOR

 

[DaEarl]

There probably is not a handy formula or at least not one that I can think of off the top of my head. I would dust off the Calculus book and set up an integral for surface area and derive the formula. I looked at it and it is not as difficult as it seems.

 

[JStephen]

I'm not sure what shape you're meaning exactly. A spherical cap has surface area 2*pi*R^2*(1-cos(A)), where A is the included half angle. Put in A=180 degrees, and you get the formula for a full sphere. If your shape is a truncated sphere, that should do it.

I would think that the formulas for heat input from a fire are highly approximate at best, so I don't know that this is something that needs to be carried to 8 decimal places.

 

[MJCronin]

Is this the shape you are talking about ?

http://www.psi-pci.com/Data_Sheets_Library/DS483.pdf

Or is this the shape ?

http://www.psi-pci.com/Data_Sheets_Library/DS485.pdf

Or does it look like this:

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20060050749_2006251926.pdf

If your tank is comprised of a cylidrical shell and two hemispherical heads, the soultion is obvious... Sum the individual areas

-MJC

 

[ChEGATOR]

MJCronin -

Thanks for your reply. The tank in question doesn't really look like either one of the tanks in the first two links. It does resemble the tank in the third link. The tank type is actually a Horton Spheroid. Page 2 of the pdf at the following link shows a picture of a Horton Spheroid that closely resembles the tank:

http://www.michigan.gov/documents/Vol2-35UIP11Tanks_121080_7.pdf

ChEGATOR

 

[unclesyd]

There is some information in thread794-174057. Specifically it mentions an old CBI Booklet.

You might just query CBI and get lucky, that is information without a fee.

 

[JStephen]

If it's a sphere on legs, I'd consider it a perfect sphere and use the equation above. If it's a flattened-out-sphere shape, then you'd need integrate the area (assuming you know the dimensions!). Otherwise, approximate.