Why E8s and not E7s?

[MechDiver]

Boogie711 once bubbled...

but that distinction is effectively gone with the E-series. Both are rated to 3442 psi. So to tell someone to do a search on HP tanks doesn't really cut it.

The shortcomings (if you believe there are any) are still there. The only thing that has really happened is the working pressure has been increased to what some of us have been using anyway. Yes, the metal is different and the weight has changed somewhat, but if you can only fill an E8-130 to 3000psi, you still have alot more air that you would have with a short filled HP. If the tanks were the same, they wouldn't offer E7 and E8.

This is yet another thing you can argue until the cows come home, and still prove nothing to anyone.

 

[FredT]

MechDiver once bubbled...


The shortcomings (if you believe there are any) are still there. The only thing that has really happened is the working pressure has been increased to what some of us have been using anyway. Yes, the metal is different and the weight has changed somewhat, but if you can only fill an E8-130 to 3000psi, you still have alot more air that you would have with a short filled HP. If the tanks were the same, they wouldn't offer E7 and E8.

This is yet another thing you can argue until the cows come home, and still prove nothing to anyone.

The E7 and E8 of the same rated volume have to have effectively the same internal water capacity. A 3000 psi fil in either bottle will provide effectivly the same useable expand volume.

FT

 

[MechDiver]

FredT once bubbled...


The E7 and E8 of the same rated volume have to have effectively the same internal water capacity. A 3000 psi fil in either bottle will provide effectivly the same useable expand volume.

FT

Alluding to the fact that many shops can't/won't fill HP tanks to rated working pressure. My primary point was that if the tanks were the same, PST wouldn't have both series available as the poster said they were the same.

Bad way to state my point I guess.

MD

 

[Genesis]

My primary point was that if the tanks were the same, PST wouldn't have both series available as the poster said they were the same.

Bad way to state my point I guess.

PST gives you a means to trade length .vs. diameter - that's it - between the E7 and E8 series of equivalent volume.

The E8-119 is the same (within a cf) of the E7-120. The E7 is lighter by a couple of pounds (empty) though. All you are effectively trading off is length .vs. girth.

 

[scubafanatic]

Hi wetvet,

So, if you had twin HP 120's filled to 3400 psi, and they're 120 cu ft @ 3442 psi, you had 237 cu. ft of air...and your dive buddies , with LP 104's filled to 3400 psi, (which are 104 cu. ft @ 2640 psi) had 268 cu. ft...so they had 13% more air available than you had.......not exactly an overwhelming advantage.


Karl

 

[Boogie711]

For voicing what I'm trying to point out...

MechDiver - I'm not trying to be stupid about this. It's a legit question - I understand the point about HP rated tanks vs LP rated tanks. But - is not an E8-130 an HP tank now???

You can talk about 'short-filling' an E7-120 (what USED to be an HP tank) and only having 108 cubic feet if you filled it to 3000 psi. But if you fill an E8-130 to 3000 psi, you have all of 117 cubic feet - or 9 feet more.

That's it.

So would that not therefore mean that all the arguments about HP tanks are now moot? And if they're not, what are the arguments?

I'm not trying to be difficult, it's a legitimate question.

 

[MrSquid]

You are not missing anything. E7's are great tanks. What you are hearing is a strange bias that exist on internet news groups and forums. Up here HP PST tanks are the norm. You see very very few LP Steel tanks. I also always wondered about the argument of not getting a good fill on the HP tanks. Every dive shop I have ever been to in the NE bank at 4k+.

 

[Birdman]

MrSquid once bubbled...
I also always wondered about the argument of not getting a good fill on the HP tanks. Every dive shop I have ever been to in the NE bank at 4k+.

For me its a question of boat fills. The boat I dive most often provides low pressure fills only.

 

[kingprawn]

Won't a E7-120 and an E8-119 have about the same volume of air at 3000? They have the same volume at 3446.

I was on a boat last week with a diver using double E8-130s. Next to my E7-120s they were huge!

Isn't the big difference that the cave divers will pump up the E-8s and LPs to 4000+? No one will pump up an E-7 or HP tank.

Then in the next breath they will tell you that high preasure tanks (E-7) will wear out your reg faster.

 

[wetvet]

I appreciate the points, and apologize for starting another one of "those" threads. I find the tanks can be low enough that they don't interfere with my head, and am quite happy with em. Glad I didn't buy a lemon.

Thanks