High pressure or low pressure tank

[John C. Ratliff]

I have several low pressure, and I mean low, scuba tanks in my inventory, but have gotten rid of the 3000 psig older AL tanks. Mine are 1800 psig (45 cubic foot doubles), 2100 psig, and the standard 71.2 cubic foot tanks (actually 64.7 cubic feet at their rated pressure of 2250 psig). If you have the newer steel cylinders with the higher pressure, and know of a dive shop that fills high pressure SCBA units for fire departments, some of those units now are rated at 4500 psig.
Scott® Safety 45-Minute 4500 PSI Carbon SCBA Cylinder - 26760 - Northern Safety Co., Inc.

I like the steel 71.2 cylinder as it is about the right size for my body, and it is nearly weightless in salt water when low on air.

SeaRat

 

[JohnN]

I am looking at getting a 120CF tank and am trying to decide if there is any downside to using a low pressure tank.

I assume that the HP tank would be harder to find someone able to to fill it all the way to 3400psi vs the 2600psi for a low pressure tank.


Am I missing anything?

I love my Sherwood/Genesis/Asahi 120 HP(s) -12.8 full, -4.6 empty (~29" in length)\

 

[DogDiver]

The advantage of 120 LP cylinders rated at 2400 psi is that when you fill them to the normal north Florida fill of 3800 psi you now have a 160+ cubic foot cylinder.
That's why LP cylinders are so popular in cave country.


Sent from my iPhone using Tapatalk

 

[BRT]

Note that the 3180# times 1.10 (10% overfill) happens to come out at 3498#. The 3442# tanks are not allowed an overfill but the useable pressure is about the same. The 3180's were just heavy slugs, but that comes off your weight belt.

 

[stevensamler]

xs scuba lp 95 series full at 2640 psi tanks are 10.1 lbs negative and 3.0 lbs negative empty. For me this tank trims out nice i'm 5'5" at 175 lbs and dive dry , i can take some of the weight off my belt because tanks are negative.

 

[Chugwhump]

The advantage of 120 LP cylinders rated at 2400 psi is that when you fill them to the normal north Florida fill of 3800 psi you now have a 160+ cubic foot cylinder.
That's why LP cylinders are so popular in cave country.

And Southeast Florida.

But not The Naples to Sorrysota area.
Tampa is spotty also.

And as for "The Keys"........
Don't make me laugh.
Those islands are populated with what is pretty certainly the highest concentration of sanctimonious and yet incredibly ignorant (and did I mention laziest) "Professional SCUBA" blowhards in the United States.

OK....
BacK to the OP's question.

I have three LP 120's. All PST (Pressed Steel) manufacture.
I also have one Faber 149.
PLEASE DONT TELL ANYONE.....
These tanks are pretty much at 3500 or better PSI between dives.
So far, so good.
I also have 3 Worthington HP130's, 2 PST HP130's, and a Faber HP130.

I LOVE, LOVE, LOVE my LP 120's.
My trim is EXCELLENT with them.
Better than when using the 130's, which ain't bad either.
However....Your results may differ.

I am a little over 6'-1" and #210.

SOO....
My recommendation is
LP, if you can get good fills.
HP, if you cannot get good fills.

Chug
Thinks that there are most certainly some great Dive Professionals in " The Keys", but knows that they are RARE.

 

[scubastingray]

Are you diving the LP120s as singles or doubles?
I'm ~6'1", 180lbs and the LP 120s were a bit much to navigate land well. I downgraded to some LP108s (not much smaller).


Also, TBone you forgot the 2730 MP. I've got a set of Fabers that are 2730+ (3003 psi with the 10% overfill). They were pretty damn rare from what I've gathered, but telling people that they're just 3000 PSI tanks usually works well because shop monkeys are used to AL80s.

 

[Pullnglide]

The advantage of 120 LP cylinders rated at 2400 psi is that when you fill them to the normal north Florida fill of 3800 psi you now have a 160+ cubic foot cylinder.
That's why LP cylinders are so popular in cave country.


Sent from my iPhone using Tapatalk

Took the words right out of my mouth. I haven't seen 3800 but I get 3600 most times.

 

[Bob DBF]

No shops I've been to have a problem filling HP tanks to pressure. Check where you are going to be filling to make sure.

I use my 2400# LP tank on boat dives when they fill tanks on board because they usually fill to 3000#, giving around 2800# for the dive unless there was time for a top off, not good for AL or HP but great for LP.

I bought a Faber MP 120, which might as well be a HP tank if you want it full, but I got a good deal. As tbone1004 posted, any LP tank can loose its + rating giving you a smaller tank real fast.

I buy my tanks when I find a good deal and figure out the niceties like weight and trim when I dive them. The only tank I'm not a fan of is the standard AL 80, haven't dove the other AL's, but I'm a cold water diver. I do get minor overfills but no cave fills out here so one tank over another for that reason is a non issue for me.



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

 

[Dnaber]

All this information and discussion about tanks is very confusing to me. I came across an issue last month when I went to purchase my first tank. I was looking at a Faber HP117. I went to my LDS and told them what I was looking at and asked if they could price match and they said yes. So they fixed me up with a tank that I thought was a HP117 but in fact it was a LP95. The LDS owner had no issue filling the LP95 tank to 3600# and I never looked initially at the tank to confirm it size. Well after getting home I was reading and writing down the serial number of the tank and I noticed it was a LP95. I called the LDS and told them that they sold me the wrong tank. The LDS owner told me that the LP95 would hold as much as a HP117 but I was afraid of such a large over fill. Was I wrong? Are my concerns misplaced? Can you over fill a tank rated at I think 2600# to 3600# safely? I guess I really need some reading material on the subject of tanks to really understand, any recommendation?

Thanks