equalizer whip...

[Icarusflies]

Hello All;

Well, I just bought my first set of AL80 doubles that I will be using when diving wet. Since for the second dive of the day I might need more gas I want to buy a transfer whip. I have found at leisure pro what they call a cross over equalizer but what puzzles me is that it is three time cheaper that other product (US$ 149) in the net http://www.leisurepro.com/Cat/Context_974/Filter_6=701/Page_1/General_Accessories/976.html. Is there a reason for that or the product is fair for what I want to do.....

I want to use the whip the simply transfer nitrox from a HP steel tank that will be filled at around 3700 psi to the AL80 set of doubles rated at 3000 psi. Is there something that I should know about transferring gas so I don't blow the boat to the mood next week end?

Thanks

 

[Aquamaniac]

Is there something that I should know about transferring gas so I don't blow the boat to the mood next week end?

Thanks

YES.....dont fill the Al80's tp 3700 PSI!!!

 

[spectrum]

What are you doing with 3700 PSI in a yoke fitted cylinder? (Oh here we go)

I'm seeing $99 at LP. Thats 1/3 cheaper than your other source. That's easily attributable to mass merchandising and probably being unbranded.

Pete

 

[Icarusflies]

All my valves are din and of course I wont feed my AL80's to 3700 psi unless I want fireworks and the captain might disapprove. However I need some differential pressure to be able to equalize so in my mind is to connect the double set, that after a first good dive might be down to lets say 1000 psi, to a HP steel tank (at 3700 psi) and SLOWLY equalize until the AL 80's are again at 3000 psi....that is my thinking / safe or not safe???

 

[Aquamaniac]

I was just kidding ya.
Youll be just fine, as long as your carefull.

Dave

 

[Land Locked]

You won't get the al80 up to 3k using a whip unless your doubles are bank bottles. I use a whip also and when you are using a cross over you are dealing with the law of diminishing returns. Safe? Everything has risk, like you stated, slowly open the valves.

 

[David P]

80*x2=160/3=53ft after first dive. 160-53=107ft you want to transfill. You would need a set of doubles larger than your 80s to acomplish this. Chances are you wouldn't even get have the gas from the HP into the doubles so assuming you have a 130 you should be able to bumb the pressure up to....130/2=65+53=128ftX(3000/160)=2400 psi.
To be honest I doubt you would get half of the gas though, Id do the math but no coffee yet this morning... good luck

 

[Icarusflies]

I plan to use a HP 100 cf tank filled at 3700 psi. If I get 100 cuf in my doubles for the second dive I am happy.

Thank you guys.

 

[redacted]

100 ft^3 at 3700 psi and 155 ft^3 at 1000 psi should equalize to 2060 psi which gives you just a hair over 100 ft^3 in your doubles. But not very efficient. A sling tank along with your doubles for the first dive would be much more efficient. An AL63 slings nicely (not so with the HP 100) and would give you about the same gas to use as your equalizing scheme.

 

[Rick Murchison]

I plan to use a HP 100 cf tank filled at 3700 psi. If I get 100 cuf in my doubles for the second dive I am happy.

Thank you guys.

A couple of things at play here... the interior volume of the HP100 just slightly more than an AL80 (about .02CF); for our purposes we can consider them the same - so double 80's have twice the interior volume of the single steel 100. What that means is that when transfilling from a 100 to double 80's you'll get a 2 psi drop in the 100 for every 1 psi rise in the 80's.
If you start at 3700 in the 100 and 1000 in the 80's, you can expect equalization at about 1900 psi (1800 drop in the 100; 900 rise in the 80's). That's just about 100 CF, so your plan's pretty good.
Back to your original question, the yoke on LP's cheapest transfil whip is pretty cheesy (I have one). I wouldn't trust it to handle 3700 psi without some eventual deformation and subsequent leaking... and if you keep it up after that, outright failure.
(I wouldn't worry about that too much... if they haven't changed 'em since I bought mine the yoke won't fit over the brass block DIN-to-yoke adapter anyway - the LP site's down right now so I can't check)
Rick