Why choose LP tanks over HP Steel tanks?

[MichaelMc]

I'm still confused between LP and HP tanks, please educate me

I obviously live in metric land, where Al is filled to 207bar (3000psi) and Steels to 232 (3364psi (ish) For Ali we have the usual candidates AL 30,40 and 80, (yes we sometime refer to them in their CU ft size) then Steels, 10, 12 & 15 which roughly translate as far as I can figure @3442psi to HP85, HP100 &HP120 respectively

Where did the LP and HP difference come from?

Why would you use LP? (I'm presuming that an LP 85 is larger than an HP85?)

Is it just filling pressures or are there other benefits?

Genuinely interested

That's obvious.

So my question to that would be, is there a huge difference in what pressure shops will fill to (to justify LP over HP) in the US?

I've described that I've gotten LP tanks at 2250. Others have described getting LP tanks at 3600 to 4000. That is a big difference. Depends on the shop.

 

[boulderjohn]

So my question to that would be, is there a huge difference in what pressure shops will fill to (to justify LP over HP) in the US?

I would guess that 3/4 of the posts in this thread are about that. My post #23 is one example.

 

[shoredivr]

As a side note, and not to derail this topic, but I believe my LDS charges a few extra bucks for a HP fill... is this typical? I would imagine it is...

Do shops charge a few extra bucks for a LP fill?

Not here.

 

[dberry]

It's interesting to hear from folks outside North America... This isn't really about metric vs. imperial, or the concept of "working pressure". LP tanks (or at least lower pressure tanks)were NEVER available across the pond? All tanks ever made and sold in EU land were designed for 200 bar (or 300 bar)? That strikes me as odd, but I'm fairly odd myself <shrug>.

 

[Diving Dubai]

I've described that I've gotten LP tanks at 2250. Others have described getting LP tanks at 3600 to 4000. That is a big difference. Depends on the shop.

I would guess that 3/4 of the posts in this thread are about that. My post #23 is one example.

Maybe my question wasn't clear.

There must have been some historical reason for the LP and HP They weren't' invented to get around shops laziness..

East of teh pond, this is just an alien concept. The choices are Steel or Ali, which you choose between for buoyancy and gas volume.

As I understand it (please correct me) you not only have Steel and Ali but LP or HP of both.. very confusing and trying to understand where the concept/requirement first came from

 

[MichaelMc]

Maybe my question wasn't clear.

There must have been some historical reason for the LP and HP They weren't' invented to get around shops laziness..

East of teh pond, this is just an alien concept. The choices are Steel or Ali, which you choose between for buoyancy and gas volume.

As I understand it (please correct me) you not only have Steel and Ali but LP or HP of both.. very confusing and trying to understand where the concept/requirement first came from

History of development and regulation. You have 200 and 300, no? Also older odd specs lying around, no?

 

[Diving Dubai]

It's interesting to hear from folks outside North America... This isn't really about metric vs. imperial, or the concept of "working pressure". LP tanks (or at least lower pressure tanks)were NEVER available across the pond? All tanks ever made and sold in EU land were designed for 200 bar (or 300 bar)? That strikes me as odd, but I'm fairly odd myself <shrug>.

I know.. We don't have burst discs either. How radical?

We did have some EU madness where thy declared that Nitrox first stages and cylinder valves would have a different thread size (M26). We just brought adaptors and ignored them in a very British way

 

[Diving Dubai]

History of development and regulation. You have 200 and 300, no? Also older odd specs lying around, no?

Fair point. I wasn't trying to be snarky, I genuinely didn't understand Perhaps @Sam Miller III can enlighten me more on the development of the HP and LP tanks

You're right about 200/300bar. I've personally never seem a 200 bar Din on a reg. All the Din cylinders i've seen (rental) have 200bar fittings which you can use a 300 bar reg on and put an insert into for Yoke. I've only seen a couple of 300bar cylinder, not popular here because of weight. I'm presuming twins would be better than a single 300bar for gas volume, maybe 300bar better as a single for weight in cold climate but I know @Storker uses 300bar so perhaps he can shed some light as to teh benefits (apart from the obvious)

 

[MichaelMc]

Perhaps @Sam Miller III can enlighten me more on the development of the HP and LP tanks

It might be a good topic for a separate thread, as it is unlikely to inform why to chose one or the other for current diving.

 

[boulderjohn]

As I understand it (please correct me) you not only have Steel and Ali but LP or HP of both..

The only HP aluminum I know of are barely HP. The standaard AL 80 is filled to 3,000 PSI, while the high pressure tank is filled to 3300 PSI--barely a difference in pressure.