How many tanks ?

[tbone1004]

Now, the NEW faber blue steel specs are different, those tanks are much longer than the PST HP100's, but the guy said PST 100's which are very different bottles. Somehow Faber magically increased internal volume, stretched the bottle almost 2 inches, PST HP100's are just shy of 24" long, the Blue Steels are almost 26", and did all of that without making the nominal capacity any bigger, but they actually did and instead of the 100's being 100cf they are actually about 113cf

If you're buying new tanks the Faber Blue Steel whatevers are about the only option, in HP or LP but those are a far cry from what most of the diving community owns. Each tank has to be evaluated for what it is, and volume is not the only thing to consider. The LP85's are 2.5lbs positive now, but they are also skinny, this allows divers to distribute weight different especially in sidemount configurations.

So yes, you are correct on one iteration of the HP100, but it is a very new one that I haven't actually seen in person, the PST HP100's, E7-100's, Worthington E7-100's are the ones you commonly see and are commonly discussed, and their capacity is actually close to nominal capacity. The new Faber 100's are brilliant tanks, and I can't wait to try them, but don't assume all 100's are made the same, even the Worthington E7-100's and PST E7-100's are wildly different bottles despite holding the same amount of gas.

Oh, and the 120's that are 15L's are actually 130cf, same as the above PST HP120, E7-120, Worthington E7-120's actually holding 120cf, the new Faber numbers are only nominal, and if you run the math they actually hold about 130cf of gas. This is VERY VERY VERY can not express how VERY important this is to know during dive planning because if you are calculating your SAC rate based off of a Faber 100 being 100cf, it will be artificially low and if you go to another bottle while travelling or whatever, you will be short on gas during dive planning. With the PST's it was the HP100 held 102, E7-100 held 100, HP120 held 122.5, E7-120 held 120, those were close enough to where the gauges had more of a deviation than that, but when you are talking about that much change in actual volume vs nominal volume, it can cause a serious shortage of gas in technical dive planning, just over 10% is a lot....

 

[Jared0425]

I started pumping them up past their recommended pressure when everyone said it would be a waste of tanks not to. If you look back on this discussion board, I started a thread about it.

I have been experimenting with slinging both ponys off to one side and having a steel and alum 40 threw me off balance pretty good. I see that only divers that have 2 alum 40s are able to pull this off. I've yet to try a slinged 80.

 

[victorzamora]

Slinging an 80 or a 40 is no big deal. I've slung an 80 and a 40 off the side with no ill effects. Slinging a steel is different. I've tried it with the super light Faber lp85s as well as lp72s. Not a fan of either.

 

[Colliam7]

I guess it may matter where your diving but a tec diver I was talking to said he would rather have larger tanks than HP tanks because many OP can not fill HP or fill short. Thoughts?

This issue - full fills with HP cylinders - comes up with some frequency, and what you see as 'thoughts' reflect two different sets of experience.

There are some divers who HAVE had a problem getting full fills on HP cylinders, and therefore recommend LP steels. There are others who HAVE NOT ever had problems getting full fills on HP cylinders, and tend to prefer them because of size / weight / trim characteristics. I happen to be in the latter group - have never encountered a dive op that could not fill to 3500 PSI, and wouldn't use one that couldn't. But, my experience is primarily east coast / Gulf / St. Lawrence diving, so maybe there are more issue in the midwest and west. I can't see how the statement 'many OP can not fill HP' could be valid. I imagine some cannot.

 

[Dr. Lecter]

I was hoping not to get into a LP vs HP discussion, but valves are valves, all modern valves are designed to take high pressure, if he's going that high which really isn't that high, it's only the burst discs that have to be replaced. When have you ever seen valves with different pressure ratings on them that were made in the last 20 years aside from the 7/8" necks?

Valves may be valves, but the rating on the burst disc they contain can matter quite a lot.

 

[Superlyte27]

If you check it out, you really have not gained anything by pumping this tank, except for over stressing it. The cubic volume difference between your LP85 and a HP100 is .1 liters. The HP tank is made to take the pressure at 3442 psi on a regular basis. The LP tank is not and if you look at the weights of the tanks you will see a slight difference in empty weight. Another point being, did you change the valve to accept the higher operating pressure you are subjecting it to. I know, all minor things, but in this day and age, points that are looked at in an accident or event that went wrong.

Please disregard this post. He has no clue what he's talking about.

---------- Post added February 13th, 2015 at 08:08 PM ----------

No debate, but check the specs on faber LP 85's. They are 13 liter volume. HP 120's are 15 liter volume. HP 100's are 12.9 liter.

Here we go again. You've been here long enough to know the math, but some how you are missing it. So here it is again....

LP85
85/2640 x 3600 = 115.9cu' of gas @ 3600PSI

HP100
100/3442 x 3600 = 104.59cu' of gas @ 3600PSI

FYI, Faber guarantees their tanks for 10,000 fills at 4000psi. So much for over stressing the steel.

---------- Post added February 13th, 2015 at 08:10 PM ----------

Slinging an 80 or a 40 is no big deal. I've slung an 80 and a 40 off the side with no ill effects. Slinging a steel is different. I've tried it with the super light Faber lp85s as well as lp72s. Not a fan of either.

The other thing is, not all Aluminum tanks are the same. I can't remember if it's Catalina, Luxfer or Hymark that float better when slung, but one is certainly the winner. I'd have to go to my dive locker to see which was which.

 

[tbone1004]

Luxfer floats better than Catalinas, not sure about Hymarks. Catalinas hang like damned bricks, their tanks are about 2lbs more negative than Luxfers.

He is right about Fabers current HP100's, but in my post I pointed out that their HP tanks are a very rough nominal capacity, vs. Worthington and PST where the numbers were either their actual capacity or in the case of the original HP tanks from PST, a rough nominal, 82, 102, and 122.5.

 

[Superlyte27]

I was more referring to the "stress"

 

[NAM001]

Octopus,

Most of your concerns i dont hink can be answered because the issues you bring are very shop dependant. For instant when i bought my tanks in early 2000's, one concern was al or steel. Many shops would not fill al tanks cause of the issue of bad al tanks. if you brought one in area you havd to have them do the vis on it. Other shops vis did not count. And then there was eddie test stuff. I think most of those issues have gone by the side. As far as al vs st, you are getting into buoyancy issues now with so many tanks. Some one will have to chime in but in general i think its steel on the back and al's for deco and im not sure which for stage. If LP85's will do the dive then a short fill on a 100 may not be a big deal at all. but if cave filled 85/s are used then you would probably want a larger hp tank than the 100. Ive never used a 100 but they seem to be all the rage from capacity and trim aspects. I use lp85's (when doubled) and larger lp's ehen single for the weight and overfill ability. And when it comes to fills i have never got a short lp fill.It usually gets filled to 3k because of lack of attention. I will say that when i take my tanks on some shops they ask when i fill them first what kind of tank, i say lp steel and they say how much do you want in them. So there is a degree of flexibility in fills when you use a lp tank over a hp or al tank. WE all know there are specific areas like mentioned that are super reasonable when it comes to fills. Many times its like pulling into a self serve station. pull up and fill a dozen tanks at once from the back of you vehicle. and some re 24/7 self serve.

All my tanks are lp tanks except the deco and that an al 40. i dont use stage.

 

[PfcAJ]

steels as stages or deco bottles suck, the ONLY exception being a steel o2 bottle for deep cave dives.