Blending and decanting

[adamr]

Originally Posted by stevechesh

If you don't have an analyser, top your twins up from the 15 and dive them on air tables, and don't go below the MOD of 32%.... Easy, sorted, and no maths involved.......

Thats basically what I do... but just wanted to know. . . .

I dive with twin 10's.

Cheers everyone

Adam

[Dave_S]

I think you'd be better of with the twin 6's - then you can put them in your pocket for the journey home on the train

[colinicky]

The really simple answer is to have 32% in the 15 as well then there's no maths involved !

[Colin Marriott]

Originally Posted by colinicky

The really simple answer is to have 32% in the 15 as well then there's no maths involved !

Or just dive the 15 for the second dive . . . then there's no decanting involved either!



ColinM

[A. Berk]

Originally Posted by Colin Marriott

Or just dive the 15 for the second dive . . . then there's no decanting involved either!
ColinM

Or lash the 15 with nitrox 32 between the 10's and suck it all back in a one-er... you'll be home in time for tea and medals!

Berk

[Roger Cardy]

I produced an excell spreadsheet to find the final fill whilst decanting.
It is initially set up to decant a 15 into a set of 12's manifolded, fill each cylinder with manifold closed then equalise the pressure. It will even calculate the final volume so you know whether it's woth decanting or not. You can change the cylinder sizes pressures etc.
As for Nitrox, agree use the same mix, or just analyse afterwards.
PM me with e mail address and i will forward you the spreadsheet.
Regards
Roger

[Air Guzzler]

why not dive with the 15 as an alternate air source

you may look at tit but at leats you will stay ther longer than the rest on your deco stop

[Bottle Maker]

sell the twin set sell the 15 litre buy a rebreather then you allways have the best mix, and non of this decanting stuff that never works quiet as the maths say it will.

Graham

[P B]

Two things you might want to think about.

1. Isolate the twins before you decant, then decant into each cylinder, then open the isolator. You will get more gas in the twins if you do it that way.

2. If going for an air top-up, just think about the equivalent nitrogen depth of the first and second dive. As if the mix is leaner on the second dive, and you goto to the same depth on both dives, you have in fact done a reverse profile for the second dive. As from a nitrogen point of view the second dive will have been deeper. Reverse profiles may be an influence on getting bent.

[MATTBIN]

Reverse profiles came up a while ago (on Divernet amongst others), I forget the exact 'rules', but from memory (please correct me if I'm wrong) it was felt that if the max dive was less than 30m and there was no more than 12m difference there was no 'clinical' evidence to suggest any greater risk from the dives.

Theory being one thing, practical experience can of course be something else

Matt