Hp tank & special permits

[mjacobydc]

I recenctly purchased a HP80 tank and realized that this is a special permit tank. Does anyone know if this is an exception for an HP tank or are all HP tanks under a special permit?
Thanks for the help!

 

[masterof0]

I know there are special permits for compressed air tanks for commercial use, but that does not apply to end users/scuba. There is nothing special about HP80's, that I am aware of, that would set it apart from any other HP, or LP, tank.

 

[Jimmer]

I know there are special permits for compressed air tanks for commercial use, but that does not apply to end users/scuba. There is nothing special about HP80's, that I am aware of, that would set it apart from any other HP, or LP, tank.

Sorry, HP tanks are different from other tanks. LP steel tanks are DOT 3AA spec'd, and hydro at 5/3 working pressure. The HP tanks dont have 3AA stamped on them, they "SPxxxx" which is "Special Permit". The PST E series tanks, ie. "Exempt" and the Worthington X series, ie. "eXempt" all get hydro'd at 3/2 working pressure.

 

[DA Aquamaster]

Scuba tanks fall into three major categories 3AL (aluminum), 3AA (Chrome Moly Steel) and special permit/exempt tanks.

As stated above the 3AL and 3AA categories are tested to 5/3rds the service pressure while special permit steel tanks are normally tested to 3/2 the service pressure.

The permits are renewed every 2 or 3 years and it is just a paperwork process. It is not an issue unless the company goes out of business in which case the paperwork to renew the permit may not get filed - unless a third party takes it on. In the event the permit is not renewed, the tanks cannot be legally requalified after their current hydro test date expires.

Currently all 3500 psi and 3442 psi steel tanks are special permit tanks.

 

[beanojones]

Currently all 3500 psi and 3442 psi steel tanks are special permit tanks.

I did not know this. The 3442s are special permits? Learn something new everyday.

Are the special permits separate for canada?

 

[dannobee]

Currently all 3500 psi and 3442 psi steel tanks are special permit tanks.

Faber manufactures 3AA tanks with a working pressure of 3498psi (3180 with a "+").

They obviously aren't special permit cylinders.

 

[Jimmer]

I did not know this. The 3442s are special permits? Learn something new everyday.

Are the special permits separate for canada?

Nope, it's the same special permit for U.S. and Canada.

Faber manufactures 3AA tanks with a working pressure of 3498psi (3180 with a "+").

They obviously aren't special permit cylinders.

No they aren't. They are god awful heavy and negatively buoyant tho.

 

[DA Aquamaster]

Faber manufactures 3AA tanks with a working pressure of 3498psi (3180 with a "+").

They obviously aren't special permit cylinders.

We agree, because they obviously are not 3442 or 3500 psi service pressure tanks. The service pressure is 3180 with an additional 10% overfill allowed on plus rated 3AA steel tanks.

In the future the difference may potentially be a moot point. The 10% overfill was allowed on a short term basis during WWII to offset a shortage in tanks for welding, etc. and was made permanent after the war. There is some difference of opinion regarding whether the plus rating needs to be redone at every hydro test, particularly given the margin of safety in 3AA tanks. There is currently some regulatory discussion of making the 10% a given and just stamping tanks with a service pressure 10% higher to start with. In other words a former 2400 psi 3AA steel tank would just have a 2640 psi service pressure and do away with the plus rating. We'll see what happens.

 

[David_57]

If anything the steel PST HP 80 at 28Lbs, is lighter than the aluminium Luxfer 80 31 Lbs, except the steel HP 80's buoyancy characteristics are far better -8 full -2.5 empty, compared to the aluminium -1.4 full +4.4 empty

 

[dannobee]

No they aren't. They are god awful heavy and negatively buoyant tho.

You say that like it's a bad thing.

(Cold water diver here, and I can dive the Faber HP100 using 12 lbs of lead on my belt)