DIN vs. yoke redux: how much air?

[rsingler]

The last DIN/yoke thread is 6 months old, but I'm an old guy (1987 card - man, was I handsome!) who is back after a decade away from diving. Catching up on stuff.
I get the O-ring thing.
For me, the whole thread didn't address the major issue as far as I'm concerned:
I think I'd like to trade in my LP steel for HP steel tanks to save a couple pounds on my back AND get more air:
Faber LP 80: 30 lb and only 71CF after you lose the +10% on a subsequent hydro.
PST HP 80: 29 lb and 82CF at 3500 psi. Empty buoyancy 1.5lb heavier, saving on my weight belt a little too.
I lose 3.5lb and gain 11CF/15% dive time.

And what if I want to extend my single tank warm water rec dives and get a 120CF tank?
Now the weight difference matters!
PST LP 120: Once I lose my +10%, my LP 120 holds 111CF at 2400psi and weighs 51lb!
Meanwhile, a
PST HP 120 holds 122.5CF at 3500 psi and only weighs 39lb.
PST HP 120 filled to 3000 psi holds 105CF and still only weighs 39lb.
I save 12 lb (empty buoyancy only .5lb different, so no lead changes), and either lose 5% or gain 9% depending upon fill pressure. But at a minimum, it's 34CF gained over an 80 for the extra 9 lb. Great!

So, how much air do you accept with yoke fittings? Do I have to go buy all DIN firsts to use HP steel?

What do all the divers with yoke regulators do when they buy a new HP steel tank?
a) only fill to 3000psi (yoke "limit") and accept the 87% of expected cu ft for dive planning (your HP80 just became a 69CF tank)
b) fill to 3442 and dive it anyway (but SP MK10 is a 3300 psi first stage - there goes HP O-ring, eventually)
c) try to fill it to 3442 but get shut down by the fill guy who sees the 3000 psi yoke you just took off
d) buy new DIN HP 1st stages

How do yoke divers with HP tanks do it?

I know I can't keep a thread from getting hijacked, but I'm really interested in hearing from those who've been there: HP tank yoke divers, or yoke divers who bought all new DIN gear to go with their HP tank. Cheers!

 

[gcarter]

232 bar = 3364 psi.

IMO well within margin of error.

I dive HP 100's with yoke regs.

 

[Drewpy]

Its not an issue..at home I dive 100hp DIN..when I travel I just put on a yoke adapter. I have not had an issue in 8 trips...

You are making mountains out of mole hills.

 

[elan]

You do not need a DIN valve/reg to dive 3442 hp tanks

 

[Peter_C]

I converted my yoke regs to DIN. Then when I dive rented tanks I swap my DIN regs back to yoke.

You can dive yoke on an HP tank. I just got tired of leaking o-rings and switched to DIN. Most of my gear is now 300 bar.

FWIW you can get the + rating upheld. Also you might find many dive shops will underfill an HP tank, but tend to overfill LP tanks. Other than a few aluminum tanks all of my steel tanks are high pressure tanks.

 

[spectrum]

Rslinger,

Wow, you have a lot going on there.

First off unless you are into a pipeline of used or lost and found product PST is only a spotty used option. XScuba has a comparable product though. Yea, things have changed in 10 yeas, PST went on hard times. Most modern HP steel cylinder (3443PSI) have a convertible valve that includes a threaded removable plug that fills the DIN port making it a yoke valve. It can be used in either configuration at will.

Now about the weight savings. The HP steels are the most efficient package going. Here is a complete comparison of an HP-80 with a Al-80. You can substitute you LP values to get a complete picture. It's not just the cylinder but also the impact on the lead you need.

With respect to dive times, the cubic foot capacity is the metric to compare. Pressure is irrelevant.

Any LP cyclinder meeting the requirements can get a + rating at any hydro. The fact that the last guy didn't bother does not disqualify the cylinder from meeting the tighter specification.

When you go to warm water the dominant cylinder is the AL-80. On occasion steel or Al-100s may be available but the 80 levels the playing field for the most part. Don't worry about weight, in tropical exposure protection you will leave so much weight on the bench in the forms of neoprene and lead the cylinder weight is inconsequential.

Yoke will do fine for any of the mentioned options up to 3442 psi and any reasonable overfill of said cylinders.

If you decide to go DIN then you have 2 options. You can add an adapter that lets you hang your DIN regulator on a yoke cylinder or.... You can buy the yoke connector parts for your regulator and swap them before and after each trip. It usualy about $ 50 for the parts and it is a 5 minute task.

Pete

 

[halocline]

One other thing I'd add is that the HP80 has a checkered reputation for trim unless you're a midget. 'Bowling ball with valve' is sometimes how you hear it described.

You should borrow or rent some different size steel tanks and try them out before you buy. Different tanks do feel different, and it's a matter of personal preference. You almost never hear of someone complaining about the size/trim/buoyancy of the HP100s, as long as you avoid the old faber 3500 PSI tanks and go with the special permit 3442 PSI tanks.

You probably do not need to replace your regs as long as they have a modern yoke. If you have a MK10 (that's what it seemed you were saying) they all have yokes capable of handling 3500 PSI with no problem. Different generations of the MK5 had lighter yokes which I personally would not trust, but I've seen divers connect the lightest of the MK5 yoke to overfilled AL80s and have no problem.

 

[LAKelpDiver]

Me and my buddies all have Faber lp95's and love them. Some are older and have been hydro'd numerous times and still have the plus rating. I think the one's that don't are only because it was not requested the last time they were done. They all have pro valve's so we can use din or yoke, we have a mix of gear anyway so it works out great. With an lp, on any boat, you are going to get a full fill, you can't always say that for hp tanks. Great bouyancy, around -8 full, -1 empty.

 

[eelnoraa]

Like every said, you don't need DIN for HP tank. I use Yoke for HP100. I prefer Yoke for single tank for convinience.