Hp Lp?

[The Natural]

So how big of a difference is it. Lets say we use 2 steel 80s one HP and one LP, how much more psi and air volume are we talking here?

 

[pants!]

An HP80 and LP80 will last exactly the same amount of time underwater since they both hold 80cf of compressed gas when they're full.

The HP80 will be physically smaller, since it packs that 80cf in with a bit more pressure.

An HP80 has a service pressure of 3500 psi, an LP80 has a service pressure of 2640 psi.. and an Al80 has a service pressure of 3000 psi.

The HP80 is the smallest and lightest (7.25" x 20", 26 lbs), then the LP80 (7.25" x 24", 32 lbs) then the Al80 (7.25" x 26", 32 lbs).

The steel LP80 and the Al80 hold the same amount of gas and are approximately the same size, but the LP80 has to have a larger internal volume to hold that amount of gas at 2640 psi instead of 3000 psi. This is explained by noting that the steel cylinder has much thinner walls because steel is much stronger than aluminum.

 

[matt_unique]

So how big of a difference is it. Lets say we use 2 steel 80s one HP and one LP, how much more psi and air volume are we talking here?

A hp 80 and a lp 80 hold the same amount of air. The lp achieves 80cf with less pressure than the hp 80.

--Matt

 

[BigJetDriver]

So how big of a difference is it. Lets say we use 2 steel 80s one HP and one LP, how much more psi and air volume are we talking here?

At the rated pressure for each tank, you will have (roughly) 80 cubic feet. The difference here is the weight and size factor of the tanks. When you start changing the pressure you pump them up to (depending upon how fearless you are), then the volume is literally all over the map.

 

[BigJetDriver]

Good morning, Msr. Petit Pants! Fast fingers you have there, laddy!

 

[pants!]

Good morning, Msr. Petit Pants! Fast fingers you have there, laddy!

There is a joke here about fingers and pants that I have a little too much decorum to make.

(but not too much decorum to post this.)

 

[O2BBubbleFree]

So how big of a difference is it. Lets say we use 2 steel 80s one HP and one LP, how much more psi and air volume are we talking here?

Q: Which weighs more, a pound of feathers or a pound of lead??

Generally speaking, US tank volume is at the rated pressure. So an HP 80 cu ft tank is exactly the same air volume as an LP 80 cu ft tank. Each has 80 cu ft at it's rated max pressure. The HP tank is physically smaller to get the same volume at a higher pressure.

WRT PSI the HP is going to be about 1000 more than the LP

Technically, though, particular manufacturers may vary a cu ft or two from their advertised rating, so if you want to get that exact, you need to compare particular brands and models of tank.

A: A pound is a pound no matter the material, and 80 cu ft is 80 cu ft no matter the packaging.

Now, if I misunderstood your question, and you are actually talking about physical size, displacement, weight, or other characteristics, you need to look at the specs of two particular models of tanks.

ADDED: Wow! you guys are fast!

 

[crpntr133]

All the above is true IF you can get a full fill on a HP.

 

[Florabama]

All the above is true IF you can get a full fill on a HP.

Qreat initial question and discussion. Couple of questions -- How hard is it to get a "full fill" with HP tanks at your average LDS, and are DIN valves absolutely required for HP tanks?

 

[pants!]

DIN valves are required on most tanks actually referred to as HP.. that's a fill pressure of 3500 psi or more. These tanks usually have smaller threads and you can only find DIN valves with those threads

PST and now Worthington produce tanks with a service pressure of 3442 psi and the same 3/4" threads as Al80s and LP tanks. Yoke valves are available for these tanks, and they come with 200 bar DIN valves with Yoke inserts so you can use any kind of regulator on them.

I've never run into a shop that can't give HP fills.