Steel HP 100 vs AL80

[Nemrod]

Or another take on LP vs HP from the spec chart. PSI-CF--Dia.--length---weight--empty--full

1. Faber/OMS LP 85 (one of my favorites)

OMS 85-- 2400 +10% --85-- 7-- 26-- 31-- 0 -- -6.7

2. Faber 80 HP

Faber 80-- 3180 +10%-- 80 --7.25-- 19.88-- 32.5-- -7.22-- -13.22

3. PST 80 HP

PST 80-- 3500-- 82-- 7.25-- 19.75-- 28.6-- -3.3-- -9.3

4. PST 100 HP

PST 100-- 3500-- 102-- 7.25-- 23.94-- 34.1-- -1.3-- -8.8

If you look with an open mind you will see that the steel LP Faber (OMS in the chart--mine are a Faber but is dimensional like the OMS) 85 is hardly larger at all, actually lighter or competive in and out of water weight, not excessively negative (better for warm water diving) and when filled to 3,000 (usually not a big problem) holds as much or more air than the 80 and 100 HP cylinders. It is not always so clear cut. Some LP tanks like the Faber/OMS 85 are awfully nice to dive and make a great double set as well. BTW, the Faber/OMS LP 85 is I recall about 97 cf at 3,000 psi, which is nothing for this super tough tank.

N

 

[Druid]

Over in the UK (and most of the rest of Europe), steel tanks are invariably cheaper than aluminium by a significant amount. Steel cylinders commonly come in 232bar working pressure, though 300bar versions are also available though they are heavier and more expensove. Al cylinders are 207bar

It's no surprise that nobody uses aluminium cylinders here, except as stage cylinders

 

[=C=]

Over in the UK (and most of the rest of Europe), steel tanks are invariably cheaper than aluminum by a significant amount. Steel cylinders commonly come in 232bar working pressure, though 300bar versions are also available though they are heavier and more expensive. Al cylinders are 207bar

It's no surprise that nobody uses aluminum cylinders here, except as stage cylinders

I would confirm this. Further I have never seen an AL80 in Czech and "cave fills" (nice slang) are "available" in Prague.

Perhaps more relevant, as a Californian I had almost no experience, the exception being a negative pool incident (rust), with anything other than an AL80. All my LDS's rented them. They [-]were[/-] are fine... I still have one in my parents garage. I would point out that the LDS doesn't rent them to you for the dive characteristics. They rent you tanks that are easy to maintain, cheapish, have lower liability, and meet the demand close enough to satisfy 89% of divers.

Since switching to steel cylinders and now doubles for my personal set, meaning a set I own and care for, I will always have steel. That being said, be it CA, FL, Mexico or Egypt, if I don't know the LDS I'd rather dive AL. With your average Red Sea charter who knows how long that tank has been sitting empty on ships deck.

-C

 

[viceroy]

And an HP tank can be limiting if your shop can't fill a tank to 3500 psi (there are some that can't do this).

Am I missing something here?

I was always led to believe that a HP tank could be safely filled to approx 4300psi (300bar) while LP tanks were limited to approx 3300psi (230bar)

Heck even my yoke fitted first stage is rated to 4000psi (276bar) by the manufacturer.

Every advert I've ever seen states that the LP tanks are 232bar and the HP are 300bar.

Also whenever I get my AL80 filled, it's never less than 2900psi (200bar) and thats considered a tight (not to capacity) fill

Can someone please explain?

 

[Scuba-Stu]

I wouldn't recommend the LP just because I have found it difficult to find anyone who will fill it beyond service pressure. I have an LP 95 with the + rating, but none of the shops here will do the overfill. My 2c.

 

[SCUBA_Phil]

Pros:
1) Holds 100 cuft @ 3442, ~80 cuft @ 3000. If your geting long dives on a 80 and dive warm water, the 80 is a better deal.
2) Takes 5 lbs of your weight belt. Important for cold water diving.

Cons:
1) Will rust if your fills are not 100% dry. Read - don't fill them on boats.
2) Cost. $350 for steel 100, $150 for Aluminum 80
3) Some fill stations won't fill above 3000 PSI

I own both and like the 100s but wont fill them on my local boats. The 100 are doubled up and used for tech diving.

Phil

 

[Air On]

Look at what/where you plan to dive...
Then get your equipment to comply with that. (including your valve style!)

If your going on trips to places that will issue you AL80s... Then get 1 or 2 AL80 so its the same rig your used to and you don't have to refigure your bouyancy and trim weight as drasticaly.

If the places you plan to dive issue steel... them buy as close to that type of tank as you can.

If you don't dive off of charter boats, resorts, with dive shops that supply the tanks... then dive anything you like as long as you can get service and fills for them.

If you don't plan to dive often... just rent the tanks when you need them.

If you are only diving on vacation or on dive trips that will supply the tanks... Then don't buy a tank at all. They will just sit in your closet/garage and never get wet.

 

[mike_s]

Am I missing something here?

I was always led to believe that a HP tank could be safely filled to approx 4300psi (300bar) while LP tanks were limited to approx 3300psi (230bar)

Heck even my yoke fitted first stage is rated to 4000psi (276bar) by the manufacturer.

Every advert I've ever seen states that the LP tanks are 232bar and the HP are 300bar.

Also whenever I get my AL80 filled, it's never less than 2900psi (200bar) and thats considered a tight (not to capacity) fill

Can someone please explain?

hmmm.... a 4300psi tanks is a rare item in Scuba here in the US. You're unlikely to find that most dive shops will be able to even fill that tank.

Your standard AL80 in the US is filled to 3000psi (rated pressure).

Most LP (Low Pressure) tanks in the US are rated at 2400psi, often with a 10% + rating for a total pressure of 2640psi

HP (High Pressure tanks) come in two different varients here. The traditional 3500psi tanks with DIN only 300bar valves, and the newer 3442psi tanks with convertible DIN/Yoke valves.


Now in all of these cases, the valve attached is typically rated at a higher PSI/bar than the valve. But you can't fill them to 300 bar for example if the tank is only rated for 3500psi. You shouldn't fill past the rated pressure that the tank is certified for. (of course some folks 'cave fill' the LP tanks over that as stated above).