MDE Valves - occasional malfunction

[Brian of Aquanauts]

Whilst filling a lot of your cylinders this summer we noticed a rare intermittent fault on MDE valves. This happened 4 or 5 times this year and last.

Sometimes when filling if our valves are turned on and the lines presurised before a customer’s valve is turned on, very occasionally their cylinder will not fill. We're looking out for it now, and listening out for the fill noise to ensure that all is well. We're guessing it might have something to do with the fact that the valves are balanced either side, so that pressure doesn't drive the slug upward as the valve is turned on.

Anyway, just wondering if many people have experienced this? We only see it in about 1 in a 1000 cases but has anyone else come across it?

Brian

[Navigator]

The same thing happened to me at capernwray, one of the staff there said it had happened before but not too often.

[David Pye]

Happened three times to me when trying to fill my RB diluent cyl (3 litre dumpy). I thought I was being dim, but I'm a bit relieved to know that it's not just me either

I noticed straight away that when I opened the compressor filling whip valve and then the cyl valve that no air moved...

[Steve S]

It's an MDE anomaly apparently, all my bottles have MDE valves and it has only ever happened to a valve on my twinset, in the same circumstances as you describe.

Safe diving,
Steve

[Woz]

We have an identical problem with a club cylinder. I would guess that the end of the spindle has come out of the slot on the slug so even if you are turning the spindle with the handle, the slug is not rotating.

If you pressurise the whip before opening the cylinder, the pressure in the whip forces the spindle up against the spindle seat. I would assume that if you open the cylinder valve first (before the whip valve) this would turn the slug as the spindle is still engaged in the slot.

The cause? I'll have a look tonight, but I would hazard an educated guess that the seat on the slug is deeply grooved allowing the slug to sit lower than normal and the spindle to come out of the slug if the valve is pressurised.

Will look at it tonight and report back, unless you could pop out of your scruffy office and have a play first.

[Brian of Aquanauts]

Originally Posted by Woz

Will look at it tonight and report back, unless you could pop out of your scruffy office and have a play first.

Scruffy office? pah, I now have polished wooden floors and a luxurious sofa to recline on no MDE valves in sight in this place so can't play

[David]

Originally Posted by Brian of Aquanauts

Scruffy office? pah, I now have polished wooden floors and a luxurious sofa to recline on no MDE valves in sight in this place so can't play

hey no one said you had a refit :-)

[Woz]

Originally Posted by Brian of Aquanauts

Scruffy office? pah, I now have polished wooden floors and a luxurious sofa to recline on no MDE valves in sight in this place so can't play

I assume you're in Laaaaaahndahn and not Plymuff Moi Luvverrrrrr.

[Brian of Aquanauts]

Originally Posted by Woz

I assume you're in Laaaaaahndahn and not Plymuff Moi Luvverrrrrr.

Yes I am in Lahnden dahling... if I scruffed this place up I'd be in trouble with

Plymouth next week tho, if anyone fancies some shore diving.

Oh it looks like the scubapro manifold occaisionally does the same thing, just waiting for confirmation from a friend.

[Woz]

Originally Posted by Brian of Aquanauts

Yes I am in Lahnden dahling... if I scruffed this place up I'd be in trouble with

Plymouth next week tho, if anyone fancies some shore diving.

Oh it looks like the scubapro manifold occaisionally does the same thing, just waiting for confirmation from a friend.

The club is diving out of Babbacoooooooooooooooombe next weekend (27/28) so if you fancy seeing what real proper faff is like then we'd be glad to welcome someone who can stand there tutting and shaking their heads. Missus Woz there too so you can pop along and we can talk The Shite.