LP or HP for doubles setup???

[Papa_Bear]

You are missing the point. just buy an HP-119 and fill it to 2640 psi and you have an LP 95 - but you have an LP 95 that you can still fill to 3442 psi iand 119 cu ft if the urge hits you.

I got the point! But I like the trim of the 95 and if I fill it 3442 I have more than your 119cu ft!

 

[WD8CDH]

the change in the tanks is not the metal but the standard that they are tested to.
LP95 is tested to DOT 3AA hydro 5/3 service pressure
HP119 aka E8-119 tested to DOT E9791 hydro 3/2 service pressure

It's much more than just the test pressure. The Special Permit also defines a specific steel alloy composition and strength. This alloy is different than what is used in the 3AA LP tanks in general and the LP95 specifically.

The HP119 aka E8-119 and the LP95 are positivly different tanks but with the same dimension.

 

[Luis H]

the change in the tanks is not the metal but the standard that they are tested to.
LP95 is tested to DOT 3AA hydro 5/3 service pressure
HP119 aka E8-119 tested to DOT E9791 hydro 3/2 service pressure

From a technical stand point I can tell that your statements are totally incorrect.

The LP tank mentioned has working pressure of 2400 psi and a test pressure of:

2400 psi x (5/3) = 4000 psi

The exception tanks have a working pressure of 3442 psi and a test pressure of:

3442 psi x (3/2) = 5163 psi

If you ever tested any of the LP (2400 psi) tanks at 5163 psi I can guaranty you that they will fail.

Hydrostatic testing is design to test the elastic expansion of a cylinder and the pressure is intended to stress the cylinder below its yield strength.

The only way a 2400 psi tank could be pressurized to 5163 psi and not experience a huge amount of yield is if they were grossly over built. If that was at all the case there would have never been a LP tank fail its intended hydro test and that is not the case.

The difference between a test pressure of 4000 psi and 5163 psi is way too large to assume that the same cylinder was just relabeled.

 

[Couv]

This has been one of the most informative threads I have read on SB. Threads like this are the reason behind my signature.

couv

 

[DA Aquamaster]

I got the point! But I like the trim of the 95 and if I fill it 3442 I have more than your 119cu ft!

Look at the chart. Other than the alloy/heat treatment, service pressures and test pressures, they are virtually the same tank with the same dimensions and for all practical purposes very close to the same weight and trim. If someone gave you an HP-119 filled to 2640 psi without you knowing it, you'd swear it was an LP 95 unless you looked at the markings on the shoulder.

 

[WD8CDH]

Not even all of the Exception tanks have a 3/2 test pressure. Some are 3/2 of service pressure, some are 5/3 and some (like the PST HP 119) are a specified gauge pressure no matter what the service pressure is. A few Exemption tanks have entirely different tests.

 

[WD8CDH]

I got the point! But I like the trim of the 95 and if I fill it 3442 I have more than your 119cu ft!

Why do you think if you fill a LP95 to 3442psi that it will have more air in it than a HP 119 at 3443psi?

 

[UaVaj]

From a technical stand point I can tell that your statements are totally incorrect.

The LP tank mentioned has working pressure of 2400 psi and a test pressure of:

2400 psi x (5/3) = 4000 psi

The exception tanks have a working pressure of 3442 psi and a test pressure of:

3442 psi x (3/2) = 5163 psi

If you ever tested any of the LP (2400 psi) tanks at 5163 psi I can guaranty you that they will fail.

Hydrostatic testing is design to test the elastic expansion of a cylinder and the pressure is intended to stress the cylinder below its yield strength.

The only way a 2400 psi tank could be pressurized to 5163 psi and not experience a huge amount of yield is if they were grossly over built. If that was at all the case there would have never been a LP tank fail its intended hydro test and that is not the case.

The difference between a test pressure of 4000 psi and 5163 psi is way too large to assume that the same cylinder was just relabeled.

Thank for verifying that I didn't just waste extra money by owning only HP tanks. At one time I thought I was buying relabeled LP tanks.


To the OP - Given the manufacturer specs alone and cost not a consideration. It is a no brainer to go with a HP setup.

 

[nereas]

I am getting ready to buy a set of doubles in the next few months. I am planning on using them in the future for trimix. I am looking considering LP95's and HP100's for my setup.

So I want some feedback on which ones and why..... Pro's and con's of each....


Thanks

Neither of your proposals is very good.

Better would be LP 85s or HP 130s.

I would suggest you get the LP 85s first, then after you are trained, get a bigger set in addition. As for how big, that depends on what you are going to do with them.

I have LP 72s and HP 130s. I use the LPs for beaches and the HPs for boats.

Then for a second beach dive, I can trans-fill the LPs from the HPs in my vehicle. Of course, you would need also to get a trans-fill hose (an HP hose with 2 DIN male sockets attached to the ends).

And for a second boat dive, I can either (1) get a boat fill, or (2) often the HPs hold enough for 2 or 3 normal dives, or else 1 really deep tech-deco dive.

You need first to answer to yourself the question, "What will you be doing with these doubles?"

If nothing much, then you want the smallest doubles, which are LP 85s (new) or LP 72s (old). These are nice and compact, and very light out of the water.

If really deep tech-deco, then HP 130s (or even HP 140s if you can lift these monsters).

And for everything else, somewhere in between.

 

[Divin'Papaw]

HP Steels. Mine are X7-100s.