Inspiration Vs Evolution: Pros & Cons of Each Please?

[beanie]

Originally Posted by Janos

EDIT: My post crossed with Beanie's. Difference in weight explains a bit. Presumably scrubber duration is non-linear because you stop when the reaction front reaches the end of the scrubber (and not when all of the scrubber is used)?

read this

srubber workings

[DaveB]

Originally Posted by beanie

FYI

2.5 on the inspo

and scrubber weight and scrubbing lifetime are not linear

ie 1 kg does not last 1/2 as long as 2kg

Just checked the tech data sheets in the manuals, Evo 2.1kg, Insp 2.45kg of Sofnolime.

I don't understand the non-linear bit, surely the Sofnolime absorbs a set mass of CO2 per kg. (from the molecular products site >140 lts of CO2 per kg.)

Cheers

[beanie]

Originally Posted by DaveB

Just checked the tech data sheets in the manuals, Evo 2.1kg, Insp 2.45kg of Sofnolime.

I don't understand the non-linear bit, surely the Sofnolime absorbs a set mass of CO2 per kg. (from the molecular products site >140 lts of CO2 per kg.)

Cheers

this is due to scrubber design and gas flows

as the scrubber gets used up it becomes less effecient

[Mark Chase]

Originally Posted by Janos

That's interesting. Nigel was showing me his until on Saturday (cheers Nigel ) and it didn't seem that heavy (well not compared to the twin 12s and stage I'd been diving earlier!) so was leaning more to the Inspiration. But if the scrubbers are almost the same size then the only difference is in the size of the tanks. But that wouldn't explain the difference in weight. Or would it?

And if the scrubbers are almost the same size, why the difference in duration?

Laters,
Confused of London

EDIT: My post crossed with Beanie's. Difference in weight explains a bit. Presumably scrubber duration is non-linear because you stop when the reaction front reaches the end of the scrubber (and not when all of the scrubber is used)?

Unit ready to go includes 12kg of lead and two full three-litre tanks.

Scrubber duration is based on the design of the scrubber and what is known as the dwell time. That said the difference in design of the Inspiration scrubber and the evo scrubber escapes me Dwell time is an issue but the fact is 5 hours out of an inspiration scrubber is common and I expect 3 hours out of an evo to be no problem

ATB

Mark Chase

[wreckweasel]

Folks,


Simple facts... as the scrubber gets used its *less* efficient. So using it deep/working hard on it when its partly used is a moving line of risk.

In plain english; A smaller scrubber (either by design or by use) doesnt scrub as well. This is particularly true at depth.

Some folks might get away with nice relaxed diving on it, but if the brown stuff hits the spinny thing, you run the risk of a meeting with Mr CO2. Using other peoples "experience" doesnt necessarily equate directly to your use.

If you truly want to push your scrubber for 5 hours, or take a dinky scrubber to 100m, I salute you and praise your bravery. However, I won't be following you..... I have an affinity for red wine, perky breasted women and thai food, none of which tend to be available after a CO2 hit at depth

You can always argue that the limits/CO2 generation used in the developement of duration testing are conservative. You are indeed correct, but you have to ask yourself how much you personally are prepared to push those limits.

Safe/fun diving... one and all!

[rooster]

Couldn't agree more about the Red wine and Thai food, there are quite a few good attractions above water as well!

My question is how much do users trust the scrubber monitor? perhaps more importantly is it going to tell me I have 1hr left on the scrubber then drop rapidly if my workrate increases and leave me in a mess?

Also, if duration is a factor of depth, what has been used to calculate 2hrs for the Evo? 20m? 30m?

My dive profiles are generally a lot of dives but relatively shallow (less than 40m) which is very different to the kind of dives someone like Mark Chase is doing for example

Hmmm, guess I really need to try both units.......

[BJ]

The scrubber monitor gives a graphic view of which part of the scrubber stack is being used. So, at the beginning on the dive it is the bottom. It moves up as you use more scrubber (the working part of the scrubber) moves higher in the stack. As you go deeper the scrubber works harder and the part in action gets higher up the stack. As you come shallower you notice some recovery of part of the scrubber lower down the stack. After three hours of diving with an Evolution with depths up to 50m my scrubber never got past halfway up the stack. Of course I would never really want the top part of the scrubber in action because that must be getting too close to CO2 breakthrough for my liking.
One thing the scrubber monitor does is give you a clear impression how the scrubber works and why you should NEVER repack a partially used scrubber. The computer download also shows the handset at any given moment in the dive and you can see how the scrubber coped. It's a good way to get an understanding.
A photograph of the actual computer display with a downloaded dive will be in the March edition of DIVER magazine.

On the subject of cylinder sizes, Big Mike has been diving a sectret military rebreather built by APD for the last year to depths up to 100m. It has only one litre cylinders. Alas, they have had to destroy it now - or they'd have to kill me!

He says that taking big bail-out cylinders with you is like buying a Porsche and tying a horse to the back in case you break down!

[And]

Originally Posted by JJJBBB

He says that taking big bail-out cylinders with you is like buying a Porsche and tying a horse to the back in case you break down!

And one might say that diving deep with small bailout cylinders is like placing a little Jesus statue on your dashboard and driving around drunk, fine until something goes wrong

Andy

PS Adapted from GI

[Rob Evans]

Originally Posted by And

And one might say that diving deep with small bailout cylinders is like placing a little Jesus statue on your dashboard and driving around drunk, fine until something goes wrong

Andy

PS Adapted from GI

You haven't met the man in question - they don't call him Mad Mike for nowt
Dived with him a couple of years ago when he had the Mil unit strapped to his back at 70m- he took the view that if you're going to go Alpinist, there's not a lot of difference between on-board 1l tins or 3l tins; if it all goes completely technical at depth you'll be just as dead with either size.

Obviously the Alpinism thing's a whole other debate - having given myself a real fright at 30m last year, I'll just carry them big tins around with me and make like a Morris Minor, ta very much..

[Decodiver]

Originally Posted by Rob Evans

he took the view that if you're going to go Alpinist, there's not a lot of difference between on-board 1l tins or 3l tins; if it all goes completely technical at depth you'll be just as dead with either size.

1 litre inboards scare the shit out of me. You only have to look at how much dil you need to clear your mask at 120m, not funny.

Cheers

Dave Cooper