Regulators will flood when upside down?

[HungoverDiver]

I've watched my son spend virtually entire dives upside down and he just keeps making bubbles. My Atomic doesn't care what orientation I might happen to be in. Some others aren't quite as forgiving. Yours seems to be broken in some way; service might be in order.

Ok, so that's what doesn't make sense. I just got the Titan LX back from annual servicing and the Zenith is brand new. The very "first" dive for both of these regs.

 

[mjrob]

What is he, from Nebraska or something?

Yeah. Crazy, eh? Did his checkout dives in Belize and has been diving in a LOT more places than I ever was at his age--even MO and AR--and I really don't get the upside down thing. But at least he dives with me. Could be worse.

---------- Post added June 2nd, 2014 at 07:26 PM ----------

Ok, so that's what doesn't make sense. I just got the Titan LX back from annual servicing and the Zenith is brand new. The very "first" dive for both of these regs.

Well Batman, you do seem to have an issue. You weren't, er...drinking or anything there, were you?

Seriously, you gots what we in the business calls a problem. Have you discussed the issue with whomever serviced the Titan? And maybe a replacement Zenith is in order...if you weren't drinking or anything. Hard to diagnose over the innerwebs, really.

 

[Subcooled]

Not sure about the amount of water in the reg... but when diving upside down or head down with my Apeks I get water in my mouth every N:th time (not every time) I inhale. It always comes as a surprise and feels unpleasant and I don't want to inhale a drop of water. I also once gave a reg upside down to my buddy during an OOA drill and he wasn't happy afterwards Cautious breathing helps as then you can abort the inhalation and clear the reg and inhale again.

 

[chillyinCanada]

Your regs aside, what's the deal with the flips on your safety stop anyway? You're supposed to be off gassing. Give your body a chance. If you're doing flips it's unlikely you are holding your stop properly.

 

[buddhasummer]

Not sure about the amount of water in the reg... but when diving upside down or head down with my Apeks I get water in my mouth every N:th time (not every time) I inhale. It always comes as a surprise and feels unpleasant and I don't want to inhale a drop of water. I also once gave a reg upside down to my buddy during an OOA drill and he wasn't happy afterwards Cautious breathing helps as then you can abort the inhalation and clear the reg and inhale again.

Mine too. HOG D1 the same. Atomic appeared dry or dry enough that I didn't notice. When inverted I just breath a little more carefully using my tongue as a "gate".

 

[halocline]

It seems to me like position should effect how much water can seep past the exhaust valve, but I can also see Halocline's point.

I don't think position affects it at all, because the entire case is surrounded by water. Any leak point will allow water in, assuming a pressure change that allows for water to enter. Air pressure inside the case at ambient is sort-of what keeps water out. The diaphragm maintains a minimum air pressure inside the case, and the exhaust valve maintains a maximum air pressure. The only difference when inverted is that the difference in depth between the exhaust valve and diaphragm now means that the overall pressure in the case is slightly lower, because the limit on maximum pressure (the exhaust valve) is slightly shallower.

But in terms of water getting in while the valve is open to let air out, that will happen regardless of it's location. Larger exhaust valves, I believe, have been somewhat shown to let more water in, and sure enough, my pilots tend to breathe a little wetter upside down than my other 2nd stages. In the pilot and air1, the diaphragm also acts as the exhaust valve, resulting in a very large exhaust valve.

To the OP, if you really got a mouthful of water, not just wet air, something is definitely wrong with the 2nd stage. The fact that it occurred just after service is a red flag; it means the service tech did something that caused the exhaust valve to seal poorly. This is not particularly unusual. Try this: either install the dustcap securely on your first stage, or connect it to a tank with the tank valve off, try inhaling on the 2nd stage. If you are able to draw any air, you have a leak, and it's likely in the exhaust valve, or possibly in the mouthpiece. Either one would result in a lot of water getting into your mouth if you inhale while you are upside down.

 

[agilis]

I've noticed that some regulators breath much wetter when inverted than others. My Scubapro 109/156 regs breath just a bit little wet when upside down, but my SP D series reg breathes much wetter; not flooded, but enough water too encourage me to change my position. The 109s seem to handle things much much better, and my 250 Graphite is the best of the bunch in that connection, with no noticable difference except a slightly reduced ease of breathing.

I once dived with a rental Dacor while on holiday. It came very close to flooding when I started examining the sealife growing on the bottom of the boat. This was a long time ago and it was pretty beat up, so who knows?

 

[halocline]

My Scubapro 109/156 regs breath just a bit little wet when upside down, but my SP D series reg breathes much wetter

The D series are the offspring of the pilot/air1 and as such have larger exhaust valves. They use an exhaust valve mounted coaxially on the center of the diaphragm instead of just using the diaphragm itself so they're not as wet as the air1, but still wetter than a conventional 2nd stage with a small exhaust valve sealing against a rigid metal or plastic case.

 

[Luis H]

Several factor affect how the mushroom valve open: geometry, position, valve stiffens, and pressure differential will all affect the exhaust valve behavior.

A vertical valve will open wider at the top than a horizontal valve (I have observed it during several experiments). The air bubble will form at the top edge and open the valve (wider). When that occurs, a little bit of water will leak just below the bubble, on the open valve edge. Note: the stiffness of the valve will affect the shape of the open valve, as in how much of the edge is lifted.

Other geometry conditions that will affect any water back-leak. For example: if there is any lip holding an air bubble just outside of the exhaust valve (in the swimming position) the regulator may be a bit dryer in the swimming position.

When the valve is in the lowest point, you also purge any moisture on every exhalation so it doesn't build up.

The pressure differential would also affect how the mushroom valve open a bit, but I haven't actually tested or observed this effect close enough to make any definitive conclusions.

The bottom line is that position does mater, but how much will depend on several factors.


Note: a number of my observations comes from studying the exhaust mushroom valves on my double hose regulator designs. I have separated the exhaust to closely observed the mushroom valve behavior. The valve is the exact same type used in a single hose regulator, but it is normally mounted on front of the diaphragm.

I have also done some in water testing with several single hose regulators, including side breathers (in a pool, the ocean, and in a bucket of water).

 

[HungoverDiver]

To the OP, if you really got a mouthful of water, not just wet air, something is definitely wrong with the 2nd stage. The fact that it occurred just after service is a red flag; it means the service tech did something that caused the exhaust valve to seal poorly. This is not particularly unusual. Try this: either install the dustcap securely on your first stage, or connect it to a tank with the tank valve off, try inhaling on the 2nd stage. If you are able to draw any air, you have a leak, and it's likely in the exhaust valve, or possibly in the mouthpiece. Either one would result in a lot of water getting into your mouth if you inhale while you are upside down.

Went diving yesterday and my primary second stage still flooded. My new Zenith secondary second stage did not (maybe me memory for the primary dives are a bit fuzzy)

Did the test you described above and was able to draw air in my recently serviced second stage. I'll take it into the shop and have them fix it.