Mushroom Valve replacement

Robert Landreth

I have noticed that problem with several flat chek valves in several other Rebreathers. Like the Kiss also uses a flat check valve but in a concave holder so it is kind of a hybrid between a mushroom valve and a flat check valve. It also puckers but just slightly, I don't think enough to be a problem. I prefer mushroom valves as there shape keeps them positively closed, until they warp then they need to bee changed. The flat ones never close completely when at rest. They rely on breathing pressure to keep one side closed, you can verify this by simply holding the valve so it is face down and blow through it and it will have a tendency to hang slightly open. Normally not as bad as your picture Thon. But the kiss valve also dos this even with the silicon sheet material that they are made out of, in the Kiss DSV it is small enough that I don't see it as a problem. In your case it seem to be open enough as to be possible problem, especially considering you have it face up and it is still open let us know how this turns out if you get the new valves or if you decide to make them your self.I would still do the test holding the check valve holder face down and seeing if they snap closed after blowing through while holding them in this position. I am very curios of how it goes. Robert.

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Rebreatherlab

Thom,

Get rid of those flappers. They are very old. If you say you just bought them it is old stock. The current Ray flappers are black silicone and do not warp. You can use Pauls check. It is the same for most or all Rebreather's. Just inhale / exhale slowly against the flow direction.
You can also check with the DSV in your mouth and the hose ends like headphones. Then breathe like you normally do. There should be a clicking sound from the flappers. If one of them dont click, the flapper could be warped. You can also replace the cable tie with a proper clip that can be opened / closed so you can visually inspect the flappers at intervals.

I had a bad call some years ago when a bloody rat had chewed a quarter of a flapper! At least the rat didnt come on the dive...

BTW, the latex discs was only on the few first prototype Pelagians. They worked ok, but with time they got a bit enlarged, plus it was a night mare to machine the seats so we skipped them. Also if you get any scubber dust on them they deteriorate quickly. If you want to make your own, get some nice silicone sheet. Or rather, start with getting the current black Ray flappers.

Andy

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SeaBass

Andy,

Good info. I just put an email into Martin to order some new ones.

Thanks,
Thom

caver99

Hi Andy,

this is not correct.
There are no old flappers or so. Just two modells from two rebreathers.

The clear white once are the once from Dolphin.

And the black are from Ray.

Both are are actual and current modells. There has never been a change on Draeger valves in last nearly 10 years or so.
So if some likes to get new Drager valves, he always has to state clear which one. They both fit both DSVs, as the internal valve holder is the same on Ray and Dolphin DSV.

So Thom, the valves you received are the Dolphin once and new of course.

Cheers

Martin

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Rebreatherlab

Martin,

Are you 100% sure about this? All my Dolphins and Rays were delivered from Draeger with clear flappers and this was around 7 - 8 years ago.

In the current price list the valve is just called R33934 Valve Disc Ray/Dolphin.

I might be wrong about this, but it seems like the black valves remain straight where as the clear valves do not. Could be a bad run, moisture in the resin or whatever......

Cheers,

Andy

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jkaterenchuk

Guys.

Thanks for completely hijacking this thread.

While you are at it I would sure like to know your thoughts on the original post question?

John

caver99

Hi Andy,

99% right I would say

T52114 is the Dolphin valve
R33934 is the Ray valve

This is stated in the actual Drager spare part list , so I think should be OK..

By the way, the R3393 is more expensive than than T52114


Just to clear that thread......sorry..again not about the original questions.

Martin

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Scubascooby

Vaguely back on topic ;-)

I did some servicing on my CK yesterday including swapping the flap parts of the non-return valves.

This is the first time I've done this on my unit. Some observations.

The use of countersunk screws is a little odd. I assembled them the way they came apart with the flap disc next to the countersunk. As the screw is screwed down it tends the buckle the flap so I left the screw protruding to avoid this.

A panel head screw might be better or alternatively assemble with the nut against the flap.

A push fit flap might prove a better option.

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jkaterenchuk

A word of caution. Be carefull when judging how much to let it protrude. There is not alot of thread for the nut to hold onto. I did the same and as a result I had a CO2 hit while decending to a 30 m wreck in a current. Luckily I recongnized the signs instead of thinking it was just overexertion and I bailed out to OC. Later I found the exhale valve and hardware in the bottom of the scrubber.

John

SeaBass

John,

Appologize for presumably getting off topic but FWIW I now have both new Drager flappers just sent to me from Martin and KISS flappers. Putting them on top of one another the Drager flappers are a little bigger so unless you cut them they would not work.

I have however gotten feedback that WOB is better with the mushrooms with the holder moulded in. Seems the screws (to be big enough to hold the mushroom) impeed WOB.

Thom

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