Question on tank buoyancy

[capt.bill]

I have a tank (steel HP100 -3500) that floats bottom up in fresh water (pool) with 500lbs of air in tank

It's suppose to be at least -1lb negative according to what I've read. What am I missing here.

here is the info on the tank:

tank info

Dot E9791 -3500 TP 5250
1A 652788 pst


I can't seem to find info - specs

Regards

 

[nimoh]

does it actually float? or just sitting on the bottom of the pool in a bottom up orientation?

my guess is that it is not completely vertical, but the bottom of the tank is up off the bottom. This could be due to the valve being heavier than the tank causing the tank shoulder to act as a fulcrum, and then the valve weighs down one side forcing the bottom up a bit.

 

[Scared Silly]

The valve and neck area are denser than the bottom thus bottoms up. I.e. the cylinder may be negatively buoyant but it is not balanced.

 

[chrpai]

I guess one easy answer is that the numbers found on the internet are.... wrong.. or put another way... close enough.

 

[thirdcoastdiver]

It looks like it is a PST Steel 100 which should have a buoyancy of -1.3 empty and -8.8 lbs. when full.

 

[redacted]

Deleted.

 

[chrpai]

Which means it should be -2 right?

 

[redacted]

Which means it should be -2 right?

Yeah - to early. I'm guessing op means it sinks with the valve down and tank bottom somewhat elevated.

 

[chrpai]

Agree it's hard to know exactly what he is seeing based on the description. FWIW, for myself, I take all these tank spec numbers published around the web as just estimates and that the final answer comes from an NB test after it's all put together into a complete rig.