Pulling a quote from the floating dock topic from this winter where I asked what the displacement of a 55 gallon drum would be.
ctenidae wrote:8*55= 440, so I'd say, not accounting for the weight of the drum itself, you get 440 pounds of flotation per drum, give or take.
So now I need some additional math/hydro-dynamics help please.
Maybe this is a no-brainer but I just don't know enough about this to figure it out myself.
Without getting into complicated specifics, from the above posting I am lead to understand that a 55 gallon drum full of air, will displace approx. 400+ lbs. of water, which I assume transforms to the ability to lift 400+ pounds of weight, out of the water.
Assuming that's true (or true enough);
- If I have four 55 gal drums submerged under a platform, when the barrels are blown dry, that should give me over 1600 lbs of lift, correct?
- If I assume I have 1000 lbs on the four barrels, assuming an even load, that means each barrel will need to displace 250 lbs. to float.
- My intent is to have a moderate sized hole on the bottom edge of each barrel, and simply bubble air in through the hole, displacing the water and forcing it out the bottom through that same hole.
- If it matters, my lake is at about 1000 ft above sea level.
- When the platform (with the 1000 lbs on it) is lifted from the water, what will be the air pressure inside the barrels (relative to ambient). Is it just 250 lbs divided by the number of cubic inches? That can't be right because air pressure is not measured volume... so what is it measured by?
- If I run a 1" hose between the barrels (at the top edge) for equalizing pressure, (and also to facilitate a vent valve for submerging) will the pressure in the hose be greater than than in the barrels? In other words if I used 2" connecting hose, would the pressure with-in that connecting hose be 1/2 of what it is in a 1" connecting hose?
What is confusing me (I think) is that pressure is measured in psi (pounds per square inch) but the drum is a 3 dimensional object, so in that context pressure should be measured in pounds per cubic inch. Since it is clearly measured in pounds per square inch (PSI), I have to assume that PSI reflects the outward pressure (per square inch) on the inside surface of the displacement container. Therefore it would be rational that a larger hose would have more surface area, and therefore less pressure per square inch. But maybe the pressure is so low it's not relevant, or maybe none of this is applicable...
Anyone who's not gotten lost in this and can offer an answer or suggestion as to how to figure this out, I'd be appreciative.
Thanks - Scott