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divedaz
20-01-2015, 02:57 AM
Do you really need one on your Rebreather?

Baloo
20-01-2015, 03:23 AM
Nope

Baloo
20-01-2015, 03:27 AM
Although in certain situations it makes life "easier", It certainly is not a prerequisite. I find my diluant usage is a lot less without one as I just use what I need.

Dsix36
20-01-2015, 03:38 AM
The only time that an ADV is actually a necessity on a rebreather is if you are not on the loop while making a descent. The rebreather will not be able to "equalize" and it will flood.

As another has stated, sometimes it is nice to have one if you happen to get task loaded.

jturner
20-01-2015, 08:15 AM
Just echoing the above really but anyway, no - you don't need one but they're a very nice-to-have. Mine's not ever given me any trouble (some people have had them running on or too tight and the like) but has been very useful when I've been busy with other things and needed some extra gas in the loop. I have yet to hear of an convincing reason as to why not to bother with one.

JPTaylor
20-01-2015, 08:44 AM
I have yet to hear of an convincing reason as to why not to bother with one.

Cost? Is an optional extra on non-PADI APD builds.

I have a flow stop with mine, sometimes I use diluent off a deep-bailout stage & have to stop the ADV adding gas.

jturner
20-01-2015, 08:51 AM
Cost? Is an optional extra on non-PADI APD builds.

I have a flow stop with mine, sometimes I use diluent off a deep-bailout stage & have to stop the ADV adding gas.

Well, you have a point to a certain degree but IMHO if you're buying a brand new rebreather yet cannot afford the extra couple of hundred for an ADV, you might want to reconsider the entire purchase or go 2nd hand - as far as I can see, one thing CCRs are very good at is consuming your money; that couple of hundred pounds is 1 set of spare cells and they'll be out of date in 18 months!

Steve C
20-01-2015, 09:20 AM
Just to reiterate the point.. a flow stop is a damned good idea with the ADV if you are using a (very) hypoxic diluent. Once all is set up, I keep it closed during surface pre-breath and initial descent to 6m, open it for rest of descent then close it pretty much for rest of dive. As said above, do you need it ..nope. . the manual add does the same... but it's nice to have and I'd certainly buy one if I bought a new CCR.

dwhitlow
20-01-2015, 09:25 AM
Do you really need one on your Rebreather?
No. When I did my mod1 I wasn't allowed to use it and it was switched off.

As the others have said it is nice to have and having a flowstop is necessary. I very much like it on the descent as it avoids that empty lungs feeling when the loop volume is compressed and you need to breathe. On the down side, if you don't switch it off when you reach depth, you will use more gas (both diluent and O2) with an adv.

It is also another collection of o rings that need loving and can let you down and my last dive was with an isolated adv for just that reason.

notdeadyet
20-01-2015, 10:14 AM
I remember Dr Mike posting a tale that he was so hammered during a co2 hit that all he could do was flush from the adv. When I felt the onset of co2 that story stuck in my head and bought me the time to bail out.

Personally, I like having one. It is not an essential but I'd rather have one than not.

It's good for loop volume control, I can feel when the lung is getting near the adv trigger. Cant say i notice using any more gas. It's good for scr'ing. It's good for when you're pulling yourself down a shot line.

I've never dived a rebreather where it was an option to not have it, I wouldn't ditch it by choice. But it isn't an essential.

I dont use a flowstop, dont like them. I just isolate at the valve. And no extra orings on mine, it's hard plumbed with compression seals and the adv unit is just a tyre valve. Not much to go wrong, upstream valve so unlikely to freeflow, 200bar rated so even if the valve seat lets go it locks up rather than dumping a load of hypoxic gas in the loop.

JPTaylor
20-01-2015, 10:46 AM
Just to reiterate the point.. a flow stop is a damned good idea with the ADV if you are using a (very) hypoxic diluent. Once all is set up, I keep it closed during surface pre-breath and initial descent to 6m, open it for rest of descent then close it pretty much for rest of dive. As said above, do you need it ..nope. . the manual add does the same... but it's nice to have and I'd certainly buy one if I bought a new CCR.

I was originally taught to close flow-stop once at the bottom or at very least before the ascent.

nigel hewitt
20-01-2015, 10:56 AM
I've dived with them back from when getting an ADV on an Inspo involved buying a kit of parts from Bob Howell and the right reg to cannibalise.
Still got it somewhere...
Actually while I was enjoying a CO2 hit it saved me from having to just hit the button and do a buoyant Polaris ascent.

I would rate it as an item I would always dive with but I would, occasionally, do a dive with it switched off just to keep the old habits going.

I also use as part of my 'two hands on the camera' trim out scheme. If I have two hands full of something else I can still trim out with the ADV.

Beware of the 'hard man' attitude to rebreathers. There are lots of things we add to make our diving easier and more fun. They also give us more ways of solving a problem. With rebreathers you always need a plan B.

ebt
20-01-2015, 11:50 AM
I remember Dr Mike posting a tale that he was so hammered during a co2 hit that all he could do was flush from the adv.

It used to be pitched as a standard drill on a meg, "open loop" they called it. Not all ADV's are that easy to breathe off though, SCR on a kiss for a while and you'll be reaching for the BOV soon (on the flip side its hard to inadvertently trigger the adv).

Of all the things you can add to a ccr, I think an ADV adds for more positives than negatives.

notdeadyet
20-01-2015, 07:05 PM
Wasnt the old Meg adv pretty much a second stage fixed into one of the lungs? I vaguely remember it being touted as good enough to breathe oc off of. I did a cave exit scr'ing on the KISS for practice once and it was tiring. Wouldnt like to have done it much longer.

I like having an adv though.

ebt
20-01-2015, 11:10 PM
Yep, wasnt it a scubapro of some sort? Pretty much how they all start out, the early kiss was a sherwood i think.

notdeadyet
21-01-2015, 12:49 AM
The one on my homebuild was a reg in a bag with a cable tie round the hose.

It worked. Occasionally.

matt
21-01-2015, 01:10 PM
Do you really need one on your Rebreather?

In the same vain of the question "do you really need to dive" then the answer is no. However I'd have one, and use it, it makes the diving things more enjoyable for me.


The only time that an ADV is actually a necessity on a rebreather is if you are not on the loop while making a descent. The rebreather will not be able to "equalize" and it will flood.

Why would it flood? Perhaps if you went deep enough it may break due to compression - but mine wouldn't flood without a rupture unless it leaked.

Matt.

Timw
21-01-2015, 02:03 PM
Wasnt the old Meg adv pretty much a second stage fixed into one of the lungs? I vaguely remember it being touted as good enough to breathe oc off of. I did a cave exit scr'ing on the KISS for practice once and it was tiring. Wouldnt like to have done it much longer.

I like having an adv though.

Don't know about the very early megs - mine was a 2.06 and came with the plunger style ADV in the lung as standard.
I use it for manual dil add as my other manual add is plumbed to my bail out. It's got an isolator as my wing is also fed from my dil so I don't really want to turn the cylinder off unless I really have to. The ADV has never leaked but the isolator slide did last weekend...

Jackaranda
21-01-2015, 05:49 PM
Think that flooding comment was made regarding a BOB

Matt
In the same vain of the question "do you really need to dive" then the answer is no. However I'd have one, and use it, it makes the diving things more enjoyable for me.



Why would it flood? Perhaps if you went deep enough it may break due to compression - but mine wouldn't flood without a rupture unless it leaked.

Matt.

hall-e
22-01-2015, 03:58 PM
No neeeeed. I'd bin the ADV on my Vision in a flash, but I'd have to buy a new T piece to replace it, so it may as well stay there for now. Bought my unit second hand so I had no choice. Used the ADV once on lesson 1 of mod 1, never used since.

IainC
23-01-2015, 03:28 PM
I would not like to be wihout my ADV, I have dived units without but to me 'hand's free' breathing at all times should be a basic feature.

Trumble
24-01-2015, 10:36 AM
Had one on mine from new with flow stop, have done about 100 hours, but stopped using it after about 20 hours. I just prefer the control of the manual add.

T.

SilentDiver
28-01-2015, 03:32 PM
I like having one.

Just use it for the descent.

I then isolate it at the bottom also find I use much less Dil this way as well.