At what pressure does a PST LP 95 = 95 csf? I assumed that 95csf of air was at 2400 psi. After doing some research on a few different websites, 95csf appears to be at the + rating (2640psi). So, in reality 2400 PSI on a PST LP 95 = 86.3~ csf of air. It appears a PST LP95 is only 95 for the first five years, then it becomes a 86! Has anyone seen this before?
PST LP Pressure Rating
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Tm530
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A well informed Hydro station can re-stamp the "+" every time your tank is Hydro'd. It is an old wives tale that it can't be done again.
Tom
Tom
A 95 is 95cf only at the 10% overfill allowed by the + rating as you guessed.
As Tm530 stated, you can get this + rating as long as the cylinder passes the additional calculations required for the + rating. Newer cylinders should have an REE number stamped on the shoulder along with everything else, this REE is used for calculating if the cylinder can receive the + rating.
Only abused cylinders will ever fail. Ive been reincarnated twice so far and Im still using cylinders from my first life
Now heres the catch: Most dive shops will tell you that the + rating is only good for the manufacturer to put on a cylinder (in other words, the first five years as you stated). Not so, and this is why if you have cylinders that have + ratings you should work DIRECTLY with a hydro facility instead of the dive shop. Most dive shops are woefully uninformed when if comes to hydros.
Roak
As Tm530 stated, you can get this + rating as long as the cylinder passes the additional calculations required for the + rating. Newer cylinders should have an REE number stamped on the shoulder along with everything else, this REE is used for calculating if the cylinder can receive the + rating.
Only abused cylinders will ever fail. Ive been reincarnated twice so far and Im still using cylinders from my first life
Now heres the catch: Most dive shops will tell you that the + rating is only good for the manufacturer to put on a cylinder (in other words, the first five years as you stated). Not so, and this is why if you have cylinders that have + ratings you should work DIRECTLY with a hydro facility instead of the dive shop. Most dive shops are woefully uninformed when if comes to hydros.
Roak
scubafanatic
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You're right, AquaGuy! On ALL low-pressure steel tanks, the advertised capacity includes the +10% overfill......to me it's a case of false advertising, since you're correct about possibly losing the 'extra' 10% after the 1st 5 years.....unless you go to the effort of finding a local hydro station that is knowledgable enough to renew the +10% rating.
It's very possible your local dive shop may try to sell you new tanks when the original hydro expires......claiming you can't renew the +10% rating...either through ignorance or the profit motive.
It's very possible your local dive shop may try to sell you new tanks when the original hydro expires......claiming you can't renew the +10% rating...either through ignorance or the profit motive.
NJdiver85
Contributor
"On ALL low-pressure steel tanks, the advertised capacity includes the +10% overfill......"
Not necessarily true. A few months ago, I was looking at either the 2002 PST or Faber catalog (I don't remember which one), and the +10% overfill was NOT needed to achieve the tanks stated capacity, at least for the newer model tanks. I suggest you contact the manufacturers directly or check out their catalogs to get the real answer.
Not necessarily true. A few months ago, I was looking at either the 2002 PST or Faber catalog (I don't remember which one), and the +10% overfill was NOT needed to achieve the tanks stated capacity, at least for the newer model tanks. I suggest you contact the manufacturers directly or check out their catalogs to get the real answer.
scubafanatic
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....so tbg, does that mean that the 'newer' model LP tanks still have a +10% rating "on-top-of" the regular 2640 psi pressure?
Does this mean such tanks are now rated @ 2904 psi (2640 + 10 %) ?
...or does this mean the tanks are just stamped to be 2640 psi tanks and the '+10 %' has been deleted off the tanks?
.......or does it mean the tanks are just rated @ 2400 psi, and that they are a big larger in internal volume, allowing them to reach full capacity @ 2400 psi?
Karl
Does this mean such tanks are now rated @ 2904 psi (2640 + 10 %) ?
...or does this mean the tanks are just stamped to be 2640 psi tanks and the '+10 %' has been deleted off the tanks?
.......or does it mean the tanks are just rated @ 2400 psi, and that they are a big larger in internal volume, allowing them to reach full capacity @ 2400 psi?
Karl
NJdiver85
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I think it means the tanks are just stamped to be 2640 psi tanks and the '+10 %' has been deleted off the tanks.
scubafanatic
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...thanks for the clarification. I'd be willing to bet the tanks haven't changed a bit from the 'old' tanks.....the downside for those of us who own the 'old' style (with the +10% stamped on the side) is that we'll have to go to the extra effort to renew the +10% rating every 5 years.
Also, I've been to one dive site that was reluctant to fill my Faber LP120's past 2400 psi.......even though they have a +10% rating......I sort of ended up in an argument with the place over it.....they gave me a hard time filling it past 2400 psi.......so if they had been rated correctly @ 2640 psi, that wouldn't have happened.
Karl
Also, I've been to one dive site that was reluctant to fill my Faber LP120's past 2400 psi.......even though they have a +10% rating......I sort of ended up in an argument with the place over it.....they gave me a hard time filling it past 2400 psi.......so if they had been rated correctly @ 2640 psi, that wouldn't have happened.
Karl
I had a similar thing happen to me ScubaFanatic - Brought some new PST 95's from a LDS. Took them to another LDS to get a fill and had a hard time getting them to fill past 2400. When I purchased an aircard for $30, they had no problem filling them up to 2700. Funny how that works!
This shouldn't cause a good hydro shop to even blink, they do + ratings all the time with the bulk cylinders (next time you see a welding setup, check out all the +s after the hydros).
My shop has a computerized setup, they enter the REE and the computer does the rest.
Roak
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