Hello, looking to buy a tank or two for this summer. I live in Minnesota so I’d like some steel cylinders for the cold water diving. What’s the difference with low pressure and high pressure tanks? And what size should I get? I have one AL80 already but would like to move to steel. Thanks
Looking to buy new tanks.
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Boarderguy
Chief Narctopus Wrangler
HP 100s or larger. Depends on your body size really. Tall, you can pull off 120s with no problem. Short, go to 119s. Want a good overall for most dives then 100 is your answer.
Boarderguy
Chief Narctopus Wrangler
runsongas
Contributor
low pressure generally refers to 3AA tanks with a service pressure of 2400 psi although some older tanks were 2250 or lower psi (aka the vintage lp72). low pressure tanks are also eligible for a + rating at hydro which allows for a 10% overfill (so 2640 and 2475 respectively).
high pressure refers to exemption tanks with a service pressure of either 3442 or 3500 psi. 3500 psi tanks used a unique neck size (7/8 unf) that necessitated 300 bar din valves. 300 bar din valves cannot be converted to be used with yoke regulators. they are not eligible for a + rating.
there are some oddball tanks like the mid pressure fabers which came in 3000 and 3180 psi flavors that were also 3AA and eligible for 10% overfill with a +. but they don't trim as well and generally are heavy (although some like them as they act as ballast in a single tank setup).
due to the substantial overengineering, it is common for low pressure tanks to be overfilled beyond DOT limits in certain areas like florida so that it can be used as a higher capacity lower weight tank. however, outside of these areas, it generally requires access to a private compressor to do so. without a "cave fill", low pressure tanks have less usable capacity for a given weight than high pressure tanks.
hot dip galvanized is preferable for salt water, but for lake diving, the painted fabers should be ok.
short answer is get a pair of hp100s so you can double them up or sidemount later if desired. or lp85s if you have access to cave fills.
high pressure refers to exemption tanks with a service pressure of either 3442 or 3500 psi. 3500 psi tanks used a unique neck size (7/8 unf) that necessitated 300 bar din valves. 300 bar din valves cannot be converted to be used with yoke regulators. they are not eligible for a + rating.
there are some oddball tanks like the mid pressure fabers which came in 3000 and 3180 psi flavors that were also 3AA and eligible for 10% overfill with a +. but they don't trim as well and generally are heavy (although some like them as they act as ballast in a single tank setup).
due to the substantial overengineering, it is common for low pressure tanks to be overfilled beyond DOT limits in certain areas like florida so that it can be used as a higher capacity lower weight tank. however, outside of these areas, it generally requires access to a private compressor to do so. without a "cave fill", low pressure tanks have less usable capacity for a given weight than high pressure tanks.
hot dip galvanized is preferable for salt water, but for lake diving, the painted fabers should be ok.
short answer is get a pair of hp100s so you can double them up or sidemount later if desired. or lp85s if you have access to cave fills.
Johnoly
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That's a great size tank to upgrade to when moving from an AL80. They are very similar in size, plus will give the diver a margin of additional air and more time. The resale value on them is also very good.
halocline
Contributor
The faber HP100s are very popular tanks, with good reason. But nobody on the internet can tell you what's best for you in your situation, there are so many variables; your size, weight requirements, gas requirements, boat vs shore diving, etc. There is no one perfect tank. That's why it would be best for you to rent or borrow a few different types of tanks and then buy what you like the best.
Eric Sedletzky
Contributor
There was an issue with certain HP tanks not long ago in that they couldn’t be filled due to the DOT permit expiring and the original manufacturer being out of business and the new owners not applying for the exemption. Very complicated, but the end result was that certain HP tanks became useless for a few months even though there was nothing physically wrong with the tank itself. There were actually two HP tanks with different ID numbers, one was OK and the other was not. Very frustrating!! I happened to own both of the those tanks BTW, a 3442-100 and a 3442-120 both with different permit numbers.
So, with LP 3AA tanks you would never have to worry about that issue, they will always be DOT compliant. Something to think about I guess.
But the HP tanks in question got recertified by DOT so they are good for the next 3-1/2 years at least.
I’m not sure if they even make those type HP tanks anymore since PST went OOB.
So, with LP 3AA tanks you would never have to worry about that issue, they will always be DOT compliant. Something to think about I guess.
But the HP tanks in question got recertified by DOT so they are good for the next 3-1/2 years at least.
I’m not sure if they even make those type HP tanks anymore since PST went OOB.
Simonturner
New
I thought this thread was started from a dude in Ukraine called Zelensky.
Would I be good to go buying a painted one if I’m only diving fresh water? When I travel I rent tanks obviously so I would never have my tanks in saltwater.
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