Steel cylinders can hold the same amount of air as aluminum cylinders, but with a smaller size and/or lower pressure?

[Angelo Farina]

No burst discs ? Why do they think their dangerous ? Guess if your careful filling tanks and don't leave them in the heat/sun you'd be OK ?

The idea of burst discs is that they will rupture in case the pressure is too large, instead of having the tank exploding.
But in reality it is much easier that a burst disc ruptures due to corrosion, leaving the diver out of gas.
Statistics show that tanks do not explode due to overpressure.
So a burst disc creates a significant risk of failure whilst providing protection against a very rare risk, which is better prevented with our mandatory hydro test every 2 years.
Here we do not have VIP either...

 

[tursiops]

Am I the only one to think this but is the + rating and the ten percent overfill to get the advertised cubic feet totally stupid and border on false advertisement?

Read the history of the + rating. Question on plus (+) sign on Steel Tanks
in fact, that whole thread is interesting.

 

[ScubaBunga]

Read the history of the + rating. Question on plus (+) sign on Steel Tanks
in fact, that whole thread is interesting.

I agree it’s interesting. But having a dozen old tanks and having to search far and wide to find a hydro tester that will still plus stamp my tanks so I can get a full fill, I also find it to be silly to still be a thing. Just accept the 10% (which is the advertised capacity!) and test accordingly.

 

[tursiops]

I agree it’s interesting. But having a dozen old tanks and having to search far and wide to find a hydro tester that will still plus stamp my tanks so I can get a full fill, I also find it to be silly to still be a thing. Just accept the 10% (which is the advertised capacity!) and test accordingly.

Get together with your dive buddies and group-purchase a compressor. Fill to whatever you want.

 

[RXTdiver]

LP95 tanks have a larger diameter than an HP100. They are essentially the same size as an HP117. For steel tanks, get the HP version of the size you want. Even if the shop won't do a full HP fill, they can at least do a 3000 or 3200psi fill, so you get 10-20% more gas than the LP version of the same size tank. This may not apply to Central FL.

FWIW, the entire world's naming schemes for tanks is stupid. You need 2 numbers to understand a tank's potential and actual gas capacity: internal volume and maximum working pressure. And yet we only get 1 number. Europeans get the internal volume and Americans get a nominal gas capacity.

95, 100 and 117. What do these numbers represent?

 

[Eric Sedletzky]

The idea of burst discs is that they will rupture in case the pressure is too large, instead of having the tank exploding.
But in reality it is much easier that a burst disc ruptures due to corrosion, leaving the diver out of gas.
Statistics show that tanks do not explode due to overpressure.
So a burst disc creates a significant risk of failure whilst providing protection against a very rare risk, which is better prevented with our mandatory hydro test every 2 years.
Here we do not have VIP either...

Install two burst discs and don’t tell anyone.

 

[Eric Sedletzky]

Read the history of the + rating. Question on plus (+) sign on Steel Tanks
in fact, that whole thread is interesting.

Yes I read the thread and I still think it’s archaic and idiotic.

 

[lexvil]

95, 100 and 117. What do these numbers represent?

Cubic feet

 

[lowwall]

95, 100 and 117. What do these numbers represent?

Nominal capacity in cubic feet of gas at the standard temperature and pressure (1 atmosphere and 20C/68F}. Multiply by 28.258 if you want the capacity in liters.

The number is calculated by multiplying the internal volume of the cylinder by its rated fill pressure. Or sometimes the fill pressure +10%. And then it's often rounded for marketing purposes.

 

[RXTdiver]

This is from the PADI website:

"How much your cylinder holds depends on its internal capacity and its rated working (maximum) pressure. One cylinder can have a higher
working pressure than another, but hold less air because the internal capacity is lower."

"but hold less air because the internal capacity is lower."

Well, wouldn't you expect that anyway?