Drager Dolphin half fill adaptor.

[Freeflow]

I believe the life of the scrubber when using the half fill adaptor is reduced by more than half, anyone confirm or deny?

[whaam68]

Hi David
in very cold water (stoney in winter) I got breakthrough in 50 odd minutes using the half fill. I didn't use it again! Time was definately not linear compared to the full scrubber so I'd be a little cautious if using one.
regards
Mike

[Janos]

Originally Posted by Freeflow

I believe the life of the scrubber when using the half fill adaptor is reduced by more than half, anyone confirm or deny?

Sorry I can't speak from experience, but I'm fairly sure that scrubber duration is NOT linear to the amount of scrubber material. At least for small amounts. This is because you're not interested in when the majority of CO2 doesn't get through, but when no CO2 gets through. (Or none critical). If you think why you might get a breakthrough at depth when you might not shallow then hopefully it will become clear.

So I would guess that it is less than half. How much less is your guess.

Personally I would just get a full fill. But that's the deal I made with myself when I went CCR. If in doubt - play safe.

Janos

[AMW]

If you are going to just go for a short ish dive and do not want a full fill then from the last dive keep some spent snof. When you stuff the scrubber fill the first half of the scrubber with this spent snof and fill the other half with new. This works very well and I have not had a problem with this way of doing the fill. This idea was given to me by some one else thank you Dunc.
Andrew.

[NotDeadYet]

What Andrew says.

It's not just scrubber life that is reduced but scrubber efficiency even when the lime is fresh. Having half the lime means you have half the dwell time. What seems like breakthrough is probably not due to lime being exhausted but the dwell time in good lime being so reduced that it isn't doing its job.

Personally, I always do a full fill. <3hrs and not deep and I leave it in the RB (my last fill was in it for 6 weeks and still worked perfectly). If it comes down to cost then bite the bullet, rebreather diving is expensive, live with it. If it's just for a bimble then I go OC rather than waste lime/O2/cell life.

[Freeflow]

I got a second hand one, for the odd night dive at Stoney or accompanying a Ray diver. I wouldn't keep part used scrubber so I have been binning some which is still good because I'm careful.

I suppose I could always cut the adaptor down a bit to make it safer...

[narked at 90]

hi ya david i had used it for 1.5 hrs but it dose say 1hr in the distruction that came with it.
i found it useful for a wile but then stopped using it as it started to seem like i was using more sorb with it!!
john

[Freeflow]

Originally Posted by narked at 90

hi ya david i had used it for 1.5 hrs but it dose say 1hr in the distruction that came with it.
i found it useful for a wile but then stopped using it as it started to seem like i was using more sorb with it!!
john

I forgot to ask you the other day! What are the oxy cell readings then?

You forgot didn't you!

[narked at 90]

Originally Posted by Freeflow

I forgot to ask you the other day! What are the oxy cell readings then?

You forgot didn't you!

hi david....strang i reply to this yesterday but it has'nt gone one to the boards
the oxy cells are 14 to 20 mv in dry air 21%
is that what you wanted?
by the way i contacted the company about buying in a load of cells but they are being a pain in the arse so I'm going to tell them to go get fucked so you may want to find the cell you want from some where else....sorry mate
kindest regards john routley

[NotDeadYet]

Originally Posted by Freeflow

I wouldn't keep part used scrubber so I have been binning some which is still good because I'm careful

I'd rather keep a part used scrubber with decent dwell time than cut down the scrubber bed depth and shorten the dwell time. You can get away with reducing the efficiency of your scrubber SCR but I wouldn't like to do it on CCR. My Ray scrubber life became a lot shorter than Draeger's figures when I used it CC.