Question How many times can I fill a steel 72 off a pair of 130s?

[inquis]

Gas Blender Toolkit will do these calcs (see the "Topoff" menu choice.

Gas blender toolkit

blender-toolkit.t-provider.de

 

[lexvil]

Without getting sciency you can fill once, and mostly fill twice.

 

[rhwestfall]

Gas Blender Toolkit will do these calcs (see the "Topoff" menu choice.

Gas blender toolkit

blender-toolkit.t-provider.de

That was the one I was thinking of! Couldn't remember it.

 

[Edward3c]

I just took my daily diver in for a vis and a fill and realized it costs me as much in fuel as it does for the fill. My thought is that it's only a little more expensive to fill my 130s than my the 72, and so if I got them all filled, how maby times could I refill the 72 off the 130s before I had to take thr whole mess back in? The 72 is 2216 psi and the 130s are 3000 psi.

This is the sort of thing we were taught during basic training, when using 200bar 100Lt storage tanks to fill our 12Lt 160bar cylinders. There is a sequence to maximise the available number of fills than can be done.

 

[rhwestfall]

This is the sort of thing we were taught during basic training, when using 200bar 100Lt storage tanks to fill our 12Lt 160bar cylinders. There is a sequence to maximise the available number of fills than can be done.

called "cascade filling"...

 

[Gone for diving]

What you really should do. Is fill all tanks, and dive all tanks.
Don't think you will find transfering is useful. The 72s are just to big. Pony tanks yeah, that works find.
But to do it regularly.... gets old fast.
And who wants to start any serious dive underfilled..... its find if your fooling around in the pool, but to drive somewhere with under fills.....
A compressor maybe in your future.
Solves all your problems.

The sad part is, it's so expensive to be cheap.

IMO Double 72s are great tanks. And a 130 will be similar size.

My buddy runs HP 130 I run double 72s.
Pst Hp 130 is 3442 psi.

 

[rhwestfall]

Where we dive, I typically dive a twinset (3442 100's or 2640 85's) for "techreational" two dive trips. Depending on the sites or plans, I usually bring along a 3442 120 that I can use to give a little top-off between dives if I feel I need it. I can then use that tank somewhere for a "fun dive" to burn the rest of the gas.

 

[davecampbell]

Where we dive, I typically dive a twinset (3442 100's or 2640 85's) for "techreational" two dive trips. Depending on the sites or plans, I usually bring along a 3442 120 that I can use to give a little top-off between dives if I feel I need it. I can then use that tank somewhere for a "fun dive" to burn the rest of the gas.

this is exactly what we do. we bring along a couple nicely filled single 100s, and top up our doubles if we're doing a third shallow dive in the afternoon.

 

[Cthippo]

ETA: Are you certain that the 130's are 3,000 psig (rather than 3,442 or 3,500)? And are you able to get the 130's "cave-filled"?

rx7diver

You are correct. I made it over to storage today looking for a sparkplug to get the boat in the water and checked the tanks. They are indeed 3442 psi. I also forgot how heavy those monsters are, and how someone used them doubled I will never know. It will be interesting trying to dive them one of these days.

Probably can't get them cave filled. LDS are pretty by the book around here. Someday I will get an air squeezer of my own.

 

[rx7diver]

... I also forgot how heavy those monsters are, and how someone used them doubled I will never know. It will be interesting trying to dive them one of these days. ...

Diving heavy doubles from a dive boat that has a "proper" ladder is straightforward.

Shore diving is a bit more challenging, however, since you might need to strap into them while they are standing on the ground, stand up in them, and walk into the water with them on your back. I was able to do this (i.e., shore dive) with my double HP120's readily enough, so long as the walking distance was not too far. Now, twenty years [ETA] and two hip replacements later, I wouldn't even try this with my HP120's.

rx7diver