DIN first stages, the reality - they get water in 'em.

[Mambo Dave]

I’m looking for any comments, suggestions, or even ‘don’t ever do that – you’ll die’ posts here. My post is just my exploration of what seems to be a small problem a few of us have, and a couple of us thought it would be a good SB question. Now I'm not sure just where to post it.

A lot of DIN users I have talked to seem to agree - water has got to be getting into the first stages, to some small degree, through normal use. I haven't asked this of yoke users, and it may be different for them. In fact, based on the years and years of yoke use in the diving community, and my own personal yoke use, it doesn’t seem to be an issue. When we were told, in our classes or our LDS’s, to keep water from going into the first stage, we obliged - it didn't seem that tough to do. However, most of the divers I dive with are using DIN, and we’re facing a different reality.

Anyway, despite the "you are going to die" type warnings (or, more appropriately, 'your fist stage is gonna die'), we're noticing that in normal use the DIN threaded area does get water on, and in, it.

We're all trying to be careful about it, obviously, but it just seems to happen. I'm not talking about flooding it out, but if even a half a drop of sea water gets in the inlet hole, well there's not really much I can do about it - especially on a cattle boat when everything is wet and we're re-tanking and jumping in.

We all know this is a bad thing, but save for getting our first stages rebuilt once a month, does anyone here believe in trying something else? Or in a lesser of two evils?

I’m not claiming to know anything, here, but this is what I’m wondering about:

A good number of us in the Ft. Lauderdale area are using a very dry, hyper-cleansed nitrox mix. This, I would guess, would help to dry out the insides of the first stage.

Now if I were to guess, I would bet that corrosive sea water and ocean contaminants are harder on a first stage than fresh water. And perhaps store-bought distilled water would be even less harsh. Our main concern, I believe, is the possible build-up of salt or the corrosiveness of the salt water.

With that in mind, and that we really don’t all go rushing to have our first stages rebuilt upon finding the first hint of water sitting in or around the inlet hole, would it be a ‘bad’ idea to flush out any salt water build up with a small amount of fresh, or distilled, water?

If a diver were to pour a little distilled water in the DIN hole and let it flow back out an open port hole, then close it up and go diving, would the dry air, flowing through the first stage, and the entire system, be enough to dry out the system on a typical AL80 dive?

If not, would leaving the first stage DIN are open, and hanging in an air conditioned house, be enough to dry it out well? Heck, is it even a question of a minute amount of water being bad inside the first stage, or is the problem with salt and corrosive contaminents instead?

Yep, I’m asking how bad of a theory this is, and for what methods of care you all take for your DIN first stages over the course of time. I have a feeling a lot of people just ignore the small amounts of water / condensation, and have the shop worry about it upon servicing. If you guys feel OK with just leaving it be, then I'd like to hear those assurances, too.

(as a side-question: do some first stage designs handle contaminants better, or actually do some seize-up or corrode faster, than others?)

Thanks, in advance, for any insight. :water: (this drop is pretty cool)

MD

 

[Mark Vlahos]

Water on the threads is not a concern of mine. Remember, the sealng surface on a DIN regulator is where the O-Ring is, not the threads. If it is a concern of yours simply open the valve a bit before you put the reg on. This will blow the small few drops of water away. Don't worry about the water that may be on the threads on your first stage since there is no chance of that water migrating to the tip of the fitting and getting inside the first stage.

True the threaded parts are essentially open to the sea during a dive, but it is just not that big a deal.

Mark Vlahos

 

[Mambo Dave]

Water on the threads is not a concern of mine.

Thanks Mark. My friends and I have been concerned about the inlet hole, not the threads. Sorry if I didn't make that clear.

Blowing it out with an air blast from the tank isn't an option, as that blows it further in.

 

[Rick Murchison]

Thanks Mark. My friends and I have been concerned about the inlet hole, not the threads. Sorry if I didn't make that clear.

Blowing it out with an air blast from the tank isn't an option, as that blows it further in.

You don't ever blast the reg... but rather simply use a blast of air before putting the regulator (or fill whip, for that matter) on the valve, to make sure the valve has no water in it. This will ensure that no water gets into the regulator (or into the tank).
Rick

 

[jagfish]

I'm with Mark here. The sealing surface is the O-ring to the inside of the threads. For water to be getting in (while sealed) it would stand to reason that air would have to be leaking out past the same O-ring, right? How could the O-ring seal keep in the air, but not keep out the water?

I haven't had this issue yet, but would have to guess that the drop must be accumulating during or after unscrewing.

 

[DA Aquamaster]

I think Mark indirectly addresed the meat of the problem. DIN valves do trap more water in them, both on the threads and potentially that water, or other splash or spray, can migrate down the outlet hole in the valve itself. From there is could get into the first stage inlet as it will be inside the o-ring sealed area.

A "flow by" balanced piston design is pretty ammenable to gas flowing through the first stage fully drying it out. An unbalanced "flow by" piston design however is not, as if any air gets through the relatively small balance holes in the piston and up into the compression chamber, it is very unlikely to remove itself absent disassembly.

Piston regs are relatively immune from damage from flooding, while diaphragm designs are potentially more prone to damage. But a lot depends on the specific design. The design also impacts to a great degree how well it will dry itself out.

A standard balanced piston design like the Conshelf or anything based, derived from it or other wise copied from it, should be pretty self drying as there are few areas where water could hide and be hard to remove. One of the few would be the small balance chamber in the seat carrier. Other designs are potentially more prone to damage and more prone to flooding that may be hard to dry without disassembly.

As for getting water out once it's in, that is very problematic. Flushing with distilled water may remove or at least dilute the salts, but it garentees a much more serious flood and that can aggravate the damage and/or drying problems. Flushing with a hygoscopic liquid like alcohol has potetenial but could damage o-rings or remove lubricants both of which would be very bad to do.

In short, the only effective technigue is to keep it dry by using a very good cap that actually seals the first stage inlet o-ring when rinsing after use and by opening tank valves slightly before use so that any water in the valve is blown out.

 

[Mambo Dave]

I better learn to not try to type with a hang-over, lol.

Sorry for not being clear guys, the drop or two of water is coming from taking the DIN valve off of the tank valve. Not from a lack of tightening or a faulty o-ring.

I'm not talking about a flood, or even what amounts to, most times, a full drop of water.

I'm guessing it either isn't happening for you guys, or few pay that close of attention to the inlet hole? A number of people I've dove with have seen it. It seems almost inevitable that on occasion (not regularly) a small amount of water - what amounts to tiny condensation droplets - is going to get both into the first-stage inlet hole and tank-valve's threaded area after pulling them apart?

Edit: and that's what I was looking for, DA Aqumaster! But all the input has been great so far - thanks guys. My fault for attempting partying and communicating in too close of a time span.

 

[Mark Vlahos]

If I get it right you are concerned with a drop or two of water on the inlet part of your first stage when you remove the first stage from the valve at the end of a dive. If that is really what you are talking about, then just give it a quick dry with a clean towel, just a dab, don't rub the heck out of it.

Mark Vlahos

 

[scubafool]

I always bleed the pressure off of my regs, back the Din fitting out about 1/2 a turn, then crack the valves again to blow any water that has seeped into the valve out through the little vent hole on the side of the valve.

 

[tangfish]

A friend of mine recently flooded my (yoke) first stage, much to my dismay. I followed the advice of my LDS and flushed the reg with fresh water then removed the ports and blew out the remaining liquid/condensation from the first and second stages.