LP vrs HP Tanks

Please register or login

Welcome to ScubaBoard, the world's largest scuba diving community. Registration is not required to read the forums, but we encourage you to join. Joining has its benefits and enables you to participate in the discussions.

Benefits of registering include

  • Ability to post and comment on topics and discussions.
  • A Free photo gallery to share your dive photos with the world.
  • You can make this box go away

Joining is quick and easy. Log in or Register now!

Influx130

Registered
Messages
10
Reaction score
0
Location
Fort Myers FL
# of dives
25 - 49
let me start by saying my search is not returning anything on this for some reason. So if there is a thread please direct me to it.

I just bought a LP 100 for cheap. I have 2 stand. 100's. The LP is heavier and about a foot taller than the normal 100's. I don't see the advantage. I understand that you can overfill these things but that is bad for the tank. It seems to me that a HP 100 would be smaller and lighter. I just don't get it :idk:.

I understand the differences between and LP and HP but can't quite rap my mind around why anyone would purchase an LP over a normal or HP tank.

Thanks,
Thomas
 
As an example consider the Worthington LP77 vs HP100

-They both have similar weight and dimensions
--LP77 weighs 32.5 lbs, is 23.2" tall
--HP100 weighs 33 lbs, is 24" tall
-The LP tank is ~$100 cheaper from most shops
-Some shops (this is very location-dependent) are comfortable filling a newer LP tank to 3000+psi
-Some shops may only fill the HP100 to around 3000psi if their bank is low, or the fill may take longer as they must run their compressor
-Consider the volume carried in each of these tanks at various pressures
--2700psi: LP77 holds 79 cu.ft, HP100 holds 78 cu.ft
--3000psi: LP77 holds 88 cu.ft, HP100 holds 87 cu.ft
--3300psi: LP77 holds 96 cu.ft, HP100 holds 95 cu.ft

If you can regularly get overfills on LP tanks or regularly have difficulty getting true HP fills, the LP tank will leave an extra $100 in your pocket and give the same utility.

If you have no problem regularly getting full HP fills and/or don't have a shop that will overfill LP steels, the extra gas you can carry may be worth the extra $100 for an HP tank.

You can do a similar comparison with other pairs of LP-HP tanks, just pick a couple that have similar dimensions and capacity at similar pressures. Comparing LP100 to HP100 is sort of an apples-oranges comparison.
 
Originally, LP tanks were the only available types of tank. But I am working on historical knowledge as i did not dive back in the day. Nowadays its almost a personal preference thing, I quite like my LP120's. They may be heavy and large (I dive them as doubles) but they fill quick, are easy to blend in and don't get as hot as the HP 120's when filling.
 
I think getting tanks which trim out well for you is more important than whether they are low or high pressure. There's a 5 inch difference in length between the Worthington HP100s and LP120s.
 
I agree about the tanks fitting the person my Alum 100's get fillled to 3400 and fit me perfect. So in summation in a nut shell:

Pro's
1.) LP tanks are cheaper
2.) You can overfill them and in many cases get the same volume as an HP
3.) Are easier for most shops to fill at the recommended volume for the tank

Con's

1.) Bigger
2.) If you overfill them they will not last as long
 
the only differnce I have heard is they weigh heavier but alot easier to get good fills. I have the X-7 HP100's which I bought because better weight/bouyancy characteristics for me and I have not had a problem yet getting a good fill I guess some areas there maybe shops that can't do this
 
let me start by saying my search is not returning anything on this for some reason. So if there is a thread please direct me to it.

I just bought a LP 100 for cheap. I have 2 stand. 100's. The LP is heavier and about a foot taller than the normal 100's. I don't see the advantage. I understand that you can overfill these things but that is bad for the tank. It seems to me that a HP 100 would be smaller and lighter. I just don't get it :idk:.

I understand the differences between and LP and HP but can't quite rap my mind around why anyone would purchase an LP over a normal or HP tank.

Thanks,
Thomas

I have yet to see any proof that overfills are bad for LP tanks and consider it a myth until I see a study that proves otherwise.
That being said, my set of Worthy HP100's are my favorite set of tanks.
 
Last edited:
I agree about the tanks fitting the person my Alum 100's get fillled to 3400 and fit me perfect. So in summation in a nut shell:

Pro's
1.) LP tanks are cheaper
2.) You can overfill them and in many cases get the same volume as an HP
3.) Are easier for most shops to fill at the recommended volume for the tank

Con's

1.) Bigger
2.) If you overfill them they will not last as long


haha, DOT rates LP tanks for 10000 hydro's at 4000PSI. anyone here (besides me) made 10000 dives on the same set of tanks?
 
I have always suspected that the metallurgy in HP & LP' is identical- is there any clear information on this matter?
Being able to overfill LP'S is a big advantage for deeper dives or otherwise a nice safety margin.

Replacing the tanks after 5 years and a hydo is your option (depending on the actual frequency of use), thus making LP's a good choice for most people.
 
I understand the differences between and LP and HP but can't quite rap my mind around why anyone would purchase an LP over a normal or HP tank.

Thanks,
Thomas

I picked up a LP95 'cause it was cheap. The weight was not an issue since I have to wear a 7mm Farmer John to dive here and any extra tank weight comes off my weightbelt. I also find I get a complete fill on boat trips ( onboard compressor ) @2400# whereas a HP100 with a slight drop in pressure, if just from cooling after the fill, will significantly affect the the quanity of air in the tank as chris b pointed out in post #2.

If I was in FL with minimal thermal protection I would also wonder why I would use a tank that would sink me like a rock without wearing a weight belt :D

Bob
--------------------------------------------
It’s such a fine line between stupid, and clever.
 
https://www.shearwater.com/products/teric/

Back
Top Bottom