NickB(Offline)

I'm not sure if this is the correct forum for something like this, there doesn't appear to be an area for Maintenence/DIY. Maybe an Admin could shift it to somewhere more appropriate if necessary....


As some of you will know, I'm a great fan of MDE manifolds due in no small part to their bombproof build and the ease with which the valves turn, even when the tanks are full.

Sadly, I no longer own a 12 litre twinset with MDE valves. The two I have currently are equipped with Scubapro and Agir-Brokk valves which, although gaining admiring glances from the guys in black, are a bugger to turn especially at high pressure.

When I first took ownership of the Scubapro manifold it clearly needed some TLC. So I stripped it down and gave it good clean & degrease followed by a soak in vinegar and an ultrasonic ‘jacuzzi’.

I reassembled the now shiny parts using Krytox grease and all seemed well, until I had the tanks filled. They were marginally better, but still unacceptable.

So, after using the gas, I stripped each valve again and made sure every surface was coated with grease. Again, a little better but not up to the high standard I was used to with MDE.

They were much easier to turn at low pressure than at high, indicating that they weren’t balancing very well. I’d noticed before that the threaded brass seat has a hole in the back (knob side) which I thought was there to assist balancing, but there doesn’t appear to be a matching hole on the other (cylinder) side. The balancing seems to take place by gas migrating through the thread which obviously takes some time.

Yesterday, I decided to take some serious action.

I stripped each valve down and gave everything a good clean up. I then took a junior hacksaw and cut a groove lengthways along the thread of the seat to a depth of about 0.5mm below the thread core. I cleaned up each thread using a needle file to remove any burrs (metal burrs and high-pressure oxygen are not good together!) and gave the thing another good clean and degrease.

After reassembling with a good coat of Krytox, everything was spinning freely, although I did notice things stiffening up when I screwed the knob back on. I noticed that, unlike the MDE valves, there’s no little Teflon washer between the valve & knob and under the pressure of the spring, there’s a lot of friction between the two metal faces. Whether Scubapro don’t use the Teflon washers or mine were just missing I know not, but I temporarily robbed some from other valves and used those.

This made a lot of difference and now things are much better, but I haven’t had the opportunity to get the tanks filled properly yet. I decanted some gas from another cylinder and at 20 Bar or so they still feel fine, but I won’t be able to get them filled up until Friday.

I’m guessing the gas should balance a lot quicker across the seat now, but if not, I can repeat the exercise with a full-size hacksaw to get a slightly wider groove.

If this proves successful, I’ll perform the same operation on the Agir manifold.

I’m guessing that most of this won’t make a lot of sense to those without an understanding of the inner workings of a pillar valve. I’ve had a quick trawl around the net for a schematic or cutaway diagram without any luck. Maybe someone else (Woz?) could post a link to one.

Now I need to track down some of those Teflon washers……

__________________
SnowHeads / BreastFriends / Free Money!

Sterny(Offline)

Great post Nick! I have been trying to figure out how to get some relief for my stiff knobs too - on a DIRZone twin manifold (I think these are similar/identical to the Agir ones made by Scubatec in Italy - not sure though).

On Friday afternoon I stopped by my dive school's equipment maintenance room and (with a bit of guidance) disassembled the valve and added a little extra O2-friendly grease to the threads (there was a bit on there already, which was good to see). I had the same results as NickB - they were nice and easy to turn with no gas in the tanks, but just as stiff as before once pressurised.

Was going to post and ask for suggestions/links, but you beat me to it mate. I'll be reading any other replies with interest - anyone else done this, got any other solutions, reckon it's not a good idea?

__________________
"I thought I had a great idea today, but it never really took off. In fact, it didn't even get on the runway. I guess you could say it exploded in the hangar." - Bill Watterson, Calvin and Hobbes

Rob Dobson (Online)

Both my Fabers and my Heisers have Scubatec manifolds (DIRZone and Agir-Brokk branded but otherwise identical). The ones on the Fabers started to get a little stiff so I stripped it down and applied the O2 grease to the right bits and it was as smooth as a smooth thing after that.

I really can't understand why you're having trouble... Definately greasing the right bits?

NickB(Offline)

They were smooth, but stiff. Now they're smoother and less stiff

I've greased every surface, there's nothing left to grease. Anyone know if Krytox is 'thicker' than Christolube? 'Cos that might make a difference I guess.

When I was at the NDAC early last month, Claire and Al were there too. While Al was off doing something (probably buying chocolate for Gledders) I took a quick peek at his twinset. The Agir valves were exactly like mine - stiff (but smooth).

Have you tried an MDE valve, 'cos these things are all relative aren't they?

__________________
SnowHeads / BreastFriends / Free Money!

Rob Dobson (Online)

Yeah my old 10's had an MDE manifold (which was very nice) but I didn't really notice any difference between that and the Scubatec ones when I switched...

Sterny(Offline)

Not sure - I can't seem to find a diagram, so if necessary I might take some photos later. I'd probably use all the wrong words if I tried to describe it, but the only two things I lubed were the threads on the brass-coloured part with a valve face on one end and a protruding flat lug on the other, which screws in and out and sits against the valve seat when it's closed, and the threads on the similar-looking part with a slot in it for the flat lug to sit in, which screws in and out and turns the brass-coloured bit. Sorry, this is probably really hard to picture unless you've taken one apart or seen one disassembled.

I didn't try lubing anything else other than the threads on those two pieces of metal. I guess that the pressure of gas acting against that brass part pushes its threads hard against the threads inside the body of the valve and the friction there is what makes it harder to open/close. Is there anything else you'd lube?

__________________
"I thought I had a great idea today, but it never really took off. In fact, it didn't even get on the runway. I guess you could say it exploded in the hangar." - Bill Watterson, Calvin and Hobbes

Rob Dobson (Online)

Do you have a copy of the Fundies book? Page 89 has an exploded view of the manifold.

O2 grease goes in *only* 2 places:

The valve seat - the contact point with the high pressure gas and the contact point on the spindle where the O-ring sits.

Ellisn did a diagram showing this a while back... Neil???

Rob Dobson (Online)

Email sent.

Sterny(Offline)

I do - I'll take a look in it tonight.
And replied to - looks like I was lubing the wrong things (the threads). I'll try it again soon!

Many thanks!

David

__________________
"I thought I had a great idea today, but it never really took off. In fact, it didn't even get on the runway. I guess you could say it exploded in the hangar." - Bill Watterson, Calvin and Hobbes

vid(Offline)

from looking at different manifolds over the last weekend, the scubatec (& agir, dirzone etc) valves
1) do seem slightly stiffer than MDE - not possible to open / shut valves with one finger, as I do with MDE
2) are a smoother action than MDE
3) do not lock open/shut as often (if at all) as the MDE does

vid