LP 95 vs. HP 100

[Luis H]

I'm not quite sure how we got off on doubles here . . .

Are you kidding? Most threads on this section of the board end up talking about doubles and/or overfilling tanks…occasionally it is about wet fills…

 

[DA Aquamaster]

It is the "tanks" forum. Tanks plural, as in doubles.

I agree though that one LP 95 is only 10 pounds heavier than an X7-100.

 

[crpntr133]

I'm not quite sure how we got off on doubles here . . . I don't see anything in the original post indicating that the author is thinking of doubling up his tanks. If you aren't thinking of doubling them, the weight differences among the tanks are not quite as daunting. But hauling doubled 95s with cave fills into the water in Florida made me feel like an overloaded pack mule

DOH!! In that case I would have to say that if I could get a full fill with the HP's I would go for it. If not then the LP95 would be my choice.

 

[Dive-aholic]

On the other hand, an LP 95 cannot be cave filled everywhere - which is to say you can't get a 3600 psi fill almost anywhere outside north florida, but an HP 130 can be legally filled to it's rated pressure almost everywhere and it is virtually the same size and weight as an LP 95.

I'm going to have to disagree here. Most shops will not fill a HP tank to its rated pressure. Most shops will only fill to 3000psi because they don't want to run their compressors any higher than that. I have found very few shops outside of N. Florida that will fill beyond 3000psi. That being said, HP100s filled to 3000psi will only give you 87 cf of gas per tank. Whereas many shops will forget to stop a LP fill at 2640 and will fill to 3000psi giving you 108 cf of gas per tank. I'd go with the 95s.

 

[RoyN]

I have both HP100 and LP95 doubles. However, I like the HP100 because it is smaller then the LP95. I would probably get another HP100 double in the future while the LP95 will be use in a rotation as well.

As for fills, yeah some shops fill them up to 3100 or some to 2800 but sometimes the air cools down and takes away 400 psi from my tank.

 

[marchand]

3600psi is not a cave fill, down here we call that a short fill. 4000psi is a cave fill and a good fill; that would give a lp95 143cf of gas.

 

[SteveTW]

Thank you all for your feedback. You're right "TSandM", I was not talking doubles at all. Just wondering about the pressure difference and what role it played in the overall picture.
I think "Luis H" explained it best, Thanks!
I get my HP100 filled to 3600psi and the LP95 gets filled to 2400psi.
Again, thank you all.
Steve

 

[DA Aquamaster]

3600psi is not a cave fill, down here we call that a short fill. 4000psi is a cave fill and a good fill; that would give a lp95 143cf of gas.

Way back when a cave fill was 2900-3000 psi - about 120%-125% of the service pressure, then it was 3400, 3500 then 3600ish. Now you are indicating it has creeped al the way up to 4000?

You do of course realize that 4000 psi is the test pressure for a 2400 psi tank? There is over filling then there is "crazy" then there is "friggin nuts". Carrying a tank around in a state of perpetual hydro test is pretty firmly in the "friggin nuts" category.

I understand the "everyone does it and no one has gotten blown up yet" argument, and is all great fun - until someone dies to make the point that the prudence got left behind long ago.

I have this interesting mental image of an overfilled LP 95 detonating at the start of a dive with a resulting chain reaction of similarly overfilled LP 95's sympathetically detonating through the whole team...

They do make larger tanks you know...

 

[Luis H]

Thank you all for your feedback. Your right "TSandM", I was not talking doubles at all. Just wondering about the pressure difference and what role it played in the overall picture.
I think "Luis H" explained it best, Thanks!
I get my HP100 filled to 3600psi and the LP95 gets filled to 2400psi.
Again, thank you all.
Steve

I think the LP95 need to be filled to 2640 (2400 + 10%) to have the rated 95 cu ft. At 2400 you are only getting about 86 cu ft.

The HP100 is at 3500 psi (or 3442 psi if it is one of the newer ones). Therefore, at 3600 psi you are actually getting 103 cu ft.


The air volume calculation is just a ratio of one pressure versus the other. This should have been covered in detail on a basic Scuba class, but many classes now-a-days doesn’t seem to be covering it well.

 

[DeepSeaExplorer]

Way back when a cave fill was 2900-3000 psi - about 120%-125% of the service pressure, then it was 3400, 3500 then 3600ish. Now you are indicating it has creeped al the way up to 4000?

You do of course realize that 4000 psi is the test pressure for a 2400 psi tank? There is over filling then there is "crazy" then there is "friggin nuts". Carrying a tank around in a state of perpetual hydro test is pretty firmly in the "friggin nuts" category.

I understand the "everyone does it and no one has gotten blown up yet" argument, and is all great fun - until someone dies to make the point that the prudence got left behind long ago.

I have this interesting mental image of an overfilled LP 95 detonating at the start of a dive with a resulting chain reaction of similarly overfilled LP 95's sympathetically detonating through the whole team...

They do make larger tanks you know...

While calculating thirds in the water, 3600 PSI is a good number. Obviously, in order to get that in 70 degree water, you need slightly more when leaving the fill station. That's pretty much standard in cave country. However, if I'm doing a bigger dive, I'll ask for the max, which at most shops is 3900. In those cases, I'm normally headed straight to the dive anyway, though there may be a lunch break in there somewhere.

Since violating thirds is one of the five risk factors for cave deaths and tank explosion is not, the need for volume far outweighs the fear of tank failure.