HP Tanks - What's the point?

[geno1]

New to this and I have a question about a steel tank, the only markings / numbers on it are HJ349631 and DOT2250.
who makes this and how do I find the year?
thganks geno

 

[RJP]

Sounds like an old LP (2250) 72. Late 60s... early 70s?

What kind of threads does it have? Can you post picture of tank neck/valve?

 

[lemke]

There are several advantages to HP tanks... more air volume (I can get 3, sometimes 4 short dives out of one tank... less tanks on my boat), and, you can carry less tanks on a deco dive. The HP "hype" works for me.

 

[SubAquatix]

So, lots of interesting input here. For me it is kind of simple. It's a tank, does it supply me enough breathing material to do what I wish? If not, there are two solutions:
1. get a bigger tank
2. jam more in it
one is a question of money, two is a question of capability and legality.

Some observations and opinions:

-If a shop, in today's market has a compressor that is unable to provide fills in excess of 3500 psi, I would wonder about the viability of that shop.
-My compressor, a Fluid Concepts model based on a Bauer Mariner, was built in 1989 as a 3500psi unit, but has since been upgraded (new 3rd stage head and valves) and includes protection mechanisms in place to stop at 4300 psi. Many Bauer compressors less than 30 years old can support such upgrade, and may require it as a part of normal maintenance. (My 3rd stage head was a requirement. LP Valves were no longer available)
-That said, with more and more HP tanks being filled, there is no doubt that the number of fills between valve replacements have gone down, indicating a higher level of wear and tear. My last ring replacement was at 1100 hours and I have 224 hours in the 2 years since then
- I run two boosters, one a repurposed Paintball booster for inert gases and less than 40%, and one dedicated to O2 over 40%. These are used to top off tri-mix blends and fill O2 takes for deco or rebreather use. Because they are air driven, they can do some draining on the air bank, but that is the cost of doing those blends.
- According to conversations with Bauer and other compressor people, startup is the hardest wear and tear on a compressor. That is the real value in having banks. Having added 6 more tanks to the cascade, I'll be curious to see how this works, but today, I rarely start my compressor that it doesn't run for a couple of hours.

 

[Bob DBF]

New to this and I have a question about a steel tank, the only markings / numbers on it are HJ349631 and DOT2250.
who makes this and how do I find the year?
thganks geno

As RJP says "Sounds like an old LP (2250) 72. Late 60s... early 70s?", before that it would have an ICC number but I don't know when that changed.

Old steel 72's are 6.9" in diameter and about 25" tall without the valve. The date of the tank would be on the first hydro mark, see the pic below.





Bob
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I honestly feel I'm a better diver now. I learned to respect the ocean the hard way. One swallow at a time. Mark Derail

 

[Dhboner]

My HP 100's trim out great in sidemount...I can dive in a drysuit with no additional weight...I can get three "shallow" dives out of them in our local shore diving spot.

 

[nimoh]

I don't see much difference between HP and LP. I dive HP 130s and a dive buddy dives LP 104s.

If he overfills and I fill to rated pressure, we both have 130cf
If I underfill and he fills to rated pressure, we both have 104cf
Generally, we both fill to about 3200...and have the same amount of gas.

The tanks are the same size, weigh the same dry and trim out the same.

 

[mjmason1]

I have 3 Faber HP100's. I love them. I wear less weight around my waist. It also gives me more air than an AL80 for a safety factor. I can't speak for a LP tank, since I have never used one.
The shops that have a problem filling HP tanks, do they sell them? All the shops in my area sell HP tanks as well as AL tanks.
I have access to a 4500lb compressor with an 8 bank system so air is never a problem for me.
Interesting to note, I think I read somewhere that, in Europe, the same tanks we fill to 3500psi, they fill to 4000psi. I think stricter regs. in USA.

 

[skankpile]

A single HP100 is a joy to dive, and comes with a 5200 burst disk. Fill it to 4200 and you have ~120cuft of air.

If you side mount a pair it in a drysuit you likely need no weight.

What I really want is a pair of the CarbonDive 300 6.8L doubles. I need to talk to my hydro guy next time I pick up cylinders as I dont know If I can get them past hydro as they have a different neck size and no DOT rating. I would be able to fill those to 300BAR+ without worry giving me 140+ cuft and weigh in the range of an AL80. It would be a great diving and transfilling setup.

 

[MXGratefulDiver]

I am asking for some intelligent dialogue on this topic for an article I am composing. The question is, "Except for those where size really does really matter, do the cons of HP steel tanks out weigh the pros?" (i.e. small divers do get a great advantage by using short steel HP thanks)

When I got back into diving and buying gear I noticed there was a big push to buy HP 100s and HP 80s. This was great for my wife. She is smaller and needed the compact size of the HP 80. It seems like the message we see from many shops is that, if you are poor you live with an aluminium 80 but if you want the best you buy and HP steel tank.

ONE PRO
The only pro of the HP steel tank over the LP steel tank seems to be the compact size. But for divers who can comfortable dive a tank that is a bit larger, why buy an HP tank? As I have
gained experience and got connected with a dive shop that HP tank pitch sounds more like hype.

LOTS OF CONS
With and HP tank (e.g. 3450 psi) I found that some shops do not even have HP compressors. Even shops that have HP compressors do not really like HP tanks. That last 400 psi create a lot of wear and tear on the compressor and the fill system. If the shop is filling from banks, it means you are going to be boosting to fill the HP tanks which wastes a lot of extra air to run the booster and attain a fill pressure. Many shops in our are will just not give you a full fill (after cooling) or want you to leave it over night if you want a full fill. Theoretically the higher presser is going to put more strain on you regulator and hp hoses. Some older yokes are not even certified to be used on HP tanks.

I keep thinking why did I get talked into this HP tank. If I had an LP 85 (2400 psi), I could fill from the banks in minutes and never have to boost. I could always get full fills wherever I travel.

What are you thoughts?

Thank you,
John

I own several different size tanks ... both HP and LP. I try to use the tank appropriate to the conditions of the dive I'm doing. On two of the dives I did this week-end ... at a place called "The Cut" in north Vancouver BC ... there's a trail that drops steeply down to where you enter the water. Getting down is a breeze ... gravity is your friend. Coming back up, I'd way rather be carrying an HP100 than an LP104. To my concern, the cons you listed really only apply when you're dealing with shops that can't fill an HP cylinder properly ... and if you're choosing to mismatch the cylinders to the type of reg you're using. Those are fairly common issues when selecting any equipment that's inappropriate to your other choices ... whether you're talking gear or conditions.

All it really points out to me is the need to consider all of your needs and equipment when making gear choices. It should match your needs in terms of capacity and compatibility. Your pros and cons usually won't be the same as mine ...

... Bob (Grateful Diver)