S100 at 3000psi?

[narcT]

What is the formula for calculating how much air a tank holds?

If I have a 100cu thats holds 98.8cu @ 3300psi how much air does the same tank hold at 3,000psi?

Just curious because half the time I hook up my reg the darn tank only shows 3,000psi

So, how much am I losing for every 100psi I'm short???

 

[Don Burke]

narcT once bubbled... What is the formula for calculating how much air a tank holds?

If I have a 100cu thats holds 98.8cu @ 3300psi how much air does the same tank hold at 3,000psi?

Just curious because half the time I hook up my reg the darn tank only shows 3,000psi

So, how much am I losing for every 100psi I'm short???

Up to about 3300, volume and pressure of air have a pretty linear relationship, so you can do some simple math.

3000 divided by 3300 gives you .909 as a ratio.

98.8 multiplied by .909 gives you 89.8 cubic feet in that tank.

That's about 3 cubic feet (there's some rounding) per 100 psi for that tank.

Above 3300 air isn't quite so linear, so you get fewer cubic feet for additional pressure.

 

[CincyBengalsFan]

You need to take it down to how many PSI is ther per Cubic Foot. For example

An 80 CF tank holds 3000 PSI. Divide 3000/80 and that gives you 37.5 PSI per cubic foot.

So the answer to you question... 3300/98.8 =33.4
3000/33.4 = 89.8

You are losing approx. 3 cubic feet for every 100 psi.

 

[narcT]

Kewl, so if I use double 100's I'll get about 180cu @ 3000psi and almost 200cu if I can get a 3300psi fill. Kewl

Thanks for the info.

 

[Don Burke]

narcT once bubbled... Kewl, so if I use double 100's I'll get about 180cu @ 3000psi and almost 200cu if I can get a 3300psi fill. Kewl

Thanks for the info.

That's a heck of a lot of weight to sling around. It would be about 92 pounds of tanks and 14 pounds of gas, plus manifold, plate, BC, lead, regulators, etc.

If you're diving dry, steel tanks will get you more gas for less weight on the boat.

If you're diving wet, a set of AL80s with an AL80 stage will give you even more gas and you can deal with the weight in pieces.

You also don't end up with two orphan tanks. You'll notice that not many people dive single 100s since you can get more gas for less weight with a steel 125.

Watch your tables and computer. That much gas can let you forget your time.

 

[Scuba_Vixen]

The real question is: "Why is someone who can't yet compute tank volume versus pressure, contemplating doubles!" A single Al100 can get most divers into a real deco nightmare ... I can imagine the potential for disaster with 2.

Al 100's make really lousy doubles ... way to much weight and hassle for minimally more (than 80's) gas.

Doubles are designed to be a great risk management tool, without proper training however, they only make it halfway....all risk, no management.

Darlene

 

[Don Burke]

Scuba_Vixen once bubbled... The real question is: "Why is someone who can't yet compute tank volume versus pressure, contemplating doubles!" A single Al100 can get most divers into a real deco nightmare ... I can imagine the potential for disaster with 2.

Al 100's make really lousy doubles ... way to much weight and hassle for minimally more (than 80's) gas.



Darlene

Good point. Nice catch.