I loaded the gun, aimed it at my head and asked my YBOD to pull the trigger.

Depth-junkie

The oring on the vision is the same as the classic, but it sits inside the can in the little dip (groove) between the scrubber and can, with the spacer on top. Were as the classic it sat loose on top of the scrubber. Same priciple and tools but different method on the vision system to the classic and this prevents dislodged orings which could happen on the classic.






ATB
Gareth

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Alpine low rider of the P.D.D.T

Padowan

Apart from the scrubber bucket being deeper on the Vision, the o-ring and spacer are installed and seal in exactly the same way. On the classic it's not exacctly what I would acll "loose" on the top - the bevelled edge of the cannister is the same on both units, and this is where the ring sits and seals once the spacer is on top. I agree that it probably "appears" to be better installed due to the depth of the bucket, whereas on my classic (with a full and well packed scrubber) I often need the pressure of the lid or certainly the depth of installation of the spacer to firmly seat the ring in it's bevel.

I've never (to my knowledge) had this ring dislodge on installatiom.

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Gilles

I'll blob for that

and this too

and the original post.

I've already posted my shame in a "near misses" thread some time ago. The result of that is a customized checklist that I fill in once each day I'm diving.

It's customized for set up efficiency on a Meg so not much use for you.

Every near miss is a lesson learned for free. Every day I shake my head at people calling other people idiots for making mistakes. All this does is make it difficult for those with near misses to share them.

Dive plenty and dive safe.

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Gilles
http://www.dirrebreather.com

streamway_explorer

Hi J,
The Mk 15.5, There is 2 of the 3 larger O rings which need to be put back in place before diving the Mk15.5. the 3rd will cause a flood of cause if not put in.where's the other 2 inner o rings which have cause Co2 hits in the past to some people, but one should notice it take some pressure to push scrubber in place when the 2 o rings are in place. 2 of the three are the same colour and almost same size. which can cause a problem if you are new to this unit.

The only reason the o rings should be taken out is because if you leave them in the grooves with the scrubber and clear top in place, is so the o rings dont go out of shape which can make it hard to pull apart after leaving for some time (more than a week or so).

But unlike the YBOD they do stay in a O ring groove. its more a question taking care of the O rings. Each mk15.5 diver has a different way of storing their units,so this has a factory too, ie scrubber put in seal container between dives weekend which make it not needed to removed these O rings. but I put the O rings in a seal bag after the weekends diving with scrubber and clear top in place on unit with O ring bag clearly visable inside the unit. making me put unit back together before each dive.

And then there is the Mk15 with its seal rubber ring for srubber which can either break inside the unit with out the diver knowing or could be left out. As far as I remember.


Michael

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Michael Collins

www.trimixdivers.com

decoweenie

The best to deal with the aforementioned MK-15 seal (i.e. wide rubber band) is following what Kevin Juergensen recommended.

Throw the rubber band away since it could break inside the unit at anytime, then you are screwed. Instead, use a wide 2" electrical tape in its place each time change the sorb. No chance of breakage, perfect seal and easy removal.

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- Rebreather World PM

jepuskar

Thanks for that Michael.

Def, I didn't catch that...ha. How you worded made you seem as if you werent the OP. In that case, feel free to call yourself an idiot.

si_b_lanzarote

having fixed o rings discourages user maintenance, the user is less likely to remove and clean then replace such o rings for a number of reasons 1 they can sometimes be a bugger to get out. 2 the user may be afraid of stretching said o ring. 3 people are just plain lazy and are less likey to do something that requires effort.

thus keeping the loose o ring makes it more likely for the user to clean and lubricate the said o ring ensuring a better seal in the system.

i dare say every inspiration/ evolution owner cleans this o ring the most out of all user maintenance tasks as its the easiest to do, be honest how often do you remove the fixed o ring and clean it?



regards si

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Gilles

That is not very good engineering design. You are purposely increasing the risk of a fatal omission, in order to improve the chances of performing a somewhat less critical maintenance.

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Gilles
http://www.dirrebreather.com

grahamsp

Been there, done that (once - never again). 67 metres, working pretty hard, total run time 79 minutes. But no hypercapnia, not even a hint, which I can only attribute to my standard practice (as recommended by Martin Parker, I think) of lubing the inside of the canister fairly liberally so that the gap is almost non-existent. Needless to say, when I finished the dive and was sorting my gear out only to see the o-ring and spacer sitting there, it was a very, very bad feeling.

Now, the o-ring and spacer never leave the canister except during disassembly and assembly.

Graham

si_b_lanzarote

i think all units have there own little design quirks, pros and cons. i think it is a little judgemental to brandish it a "bad engineering design" there are pros and cons for both solutions after all if we took all the "bad engineering designs" into account we probably wouldn't dive any rebreather as they all have their idiosyncrasies (incidentaly have you looked at your cell/loop arrangement recently?) we can pick problem and improvement with all units.

and with regards to the actual o ring you say "fatal omission" i say "careless or incompetant user"

more discipline is required for CCR diving, people should recognise and accept this when they sign up for a course, and not whine that a unit hasn't been made to cater for sloppy set up practices.

i think the proverb about workman and tools is fitting
my 2 cents.

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