HIGH PRESSURE TANK vs LOW PRESSURE TANKS...?

[Bob DBF]

If I had to choose one type I would go LP.

That being said, is the only tool in your toolchest a hammer?

I have a number of different tanks and depending on the dive I was planning I would grab the tank I thought was most suited. No sense using a HP100 when an old steel '72 will have enough air for the dive. And when I'm away from fills and need lots of tanks I bring along the AL80's as well.



Bob
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I may be old, but I’m not dead yet.

 

[LowDrag]

I would not rush with hp100. Try other tanks.

Depending on the make and your height they can be aweful or can be awesome.

Xs hp100 have a great weight to volume ratio and great buoyancy characteristics but thie trim characteristics for taller people suck as they are short.

If you only dive singles they are ok but if you will look into doubles later you have to consider you height.

I had hp100 and sold them for reasons mentioned above.

If I was buying the tanks again I would go with faber lp85. Thats the best tank I have found so far for the rec. Its easy to fill it to 3000 and it holds about 95 cuf. Its light and not buoyant as al80

The issue with hp is you have to pump them to 3800-3900 to get 3500 at rhe end. Not many shops would do that even if they have an ability. Here they usually fill them to 3500 and top them up and thats takes a lot of time.

I hated hp tanks because of that and got rid of all ofthem

I am not a scuba tank expert here or anything but one thing I keep seeing is someone saying you can get more volume than a tank is rated for. I posted some spec's earlier and no where on there does it say any of the HP tanks can hold more volume than they are rated for. Now, I get that there could be a little wiggle room but +/-10 cuf worth of wiggle room? Volume is volume and from what I have learned so far, you cannot increase volume by increasing pressure right? Or am I missing something?

 

[James R]

If an LP85 is 85ft³ at 2400psi, then it will be 106.25ft³ at 3000psi and 123.95 at 3500psi.

tank volume calculator

 

[LowDrag]

If an LP85 is 85ft³ at 2400psi, then it will be 106.25ft³ at 3000psi and 123.95 at 3500psi.

tank volume calculator

Thanks James...I must have misread the other information. I appreciate the calculator.

 

[Superlyte27]

If an LP85 is 85ft³ at 2400psi, then it will be 106.25ft³ at 3000psi and 123.95 at 3500psi.

tank volume calculator

Your calculator is incorrect. A faber lp85 is an 85cu' tank when filled to 2640. So 85/2640*3500= 112.69

 

[James R]

Your calculator is incorrect. A faber lp85 is an 85cu' tank when filled to 2640. So 85/2640*3500= 112.69

First of all it is not my calculator. Second I said if an LP85 is 85 at 2400, not that it is.

The point of my post was only to show that increased pressure in the tank does give more volume. So if you put in the 85 and 2640 then 3500 psi you do get 112.68, but you pretty much missed my point completely either way.

 

[Superlyte27]

I didn't miss any point. I was just correcting the information.

 

[RonFrank]

There you have it!

The questions you need to ask yourself before dropping you dimes on a tank.

• Can an AL80 provide enough gas for an average dive. Like say 60' avg for 60 minutes.
• If not do you get an adequate amount of dive time from an AL80 or maybe a Steel 85?
• Can you afford Steel?
• Are you willing to lug around a Steel tank?
• Is renting a better option?
• What is the best form factor for Me?

Steel tanks are nice and they solve some weight issues, like you need less weight as the are negative empty. I like 100CF tanks when doing a flat deeper profile like 70-100+ft. HP100s are also a standard form factor 7 1/4 inch in diameter. Make sure whatever you decide that it is a good long term solution to your diving needs. Also consider nitrox if you buy new as that is the time to decide. Making tanks Nitrox once they are used for standard gas just costs more. O2 cleaning is an expensive job. New tanks are typically Nitrox ready from the factory.

Me, I would rent for a bit. Good Luck!

 

[Superlyte27]

Dear God, now we've moved to the myth of O2 cleaning for Nitrox.

 

[RonFrank]

Hmmm, I understand more than many about Nitrox fills. But if you have your tanks filled by the LDS, Nitrox cleaning is hardly a myth as that is what They will require. You of all people should be aware of how this game works. So, what is your point?