Regulator sounds
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LeadTurn_SD
Contributor
Welcome to scubaboard, aussdoc.
Are the sounds heard just on the surface, just underwater, or both? Can you tell whether the noise is comming from the 1st or 2nd stage? Does the noise happen with every breath, or is it intermittent?
With the above info, I'm sure you'll get some answers.
Best wishes.
I've never rebuilt an EOS, but I've rebuilt a fair number of regs now, and heard a lot of different sounds. One sound is a diaphragm rattle when you breathe in on the second stage above water. This, to me, can sound like a moose in heat. This sound should go away underwater. It's caused by a harmonic between the diaphragm and the demand lever and can be exacerbated by slop between the lever and the diaphragm.
A second moose-like sound can be caused on the exhalation by the exhaust valve(s). Again, this is just rattling and should go away under water.
A third sound, and one that is unique to DVT first stages like the EOS, is caused by the DVT system. When you first pressurize a DVT first stage, there is a huge pressure imbalance across the red DVT plug. This imbalance causes the plug to open and allows air to flow into the first stage from the tank. When the first stage locks up, the DVT plug closes up. It stays this way until you take a breath off the second stage. Once again, there is a pressure differential across the plug which forces the plug to open. The restricted opening in the intake causes air to hiss by the plug, and you can hear that. The restriction also makes the first stage slower to re-achieve lockup pressure, so the hiss continues for a second or so after you quit inhaling. I've had customers ask about the funny noise their reg makes underwater and I can duplicate it on the flow bench. I've had one customer request I take the DVT plug out of the reg, which I did. The noise went away. I think this noise is just the price one pays for having the DVT system on his reg. I've heard this noise off many Oceanic and Aeris regs, and I've seen a few DVT regs that don't make the noise at all. I'm not sure why some do and some don't.
None of these noises should be dangerous and you're not doing anything wrong. Just to be safe, though, if I were you I'd take my reg to the shop and verify with the service tech that the sound is benign and not indicative of something worse.
Hope this answers your question.
A second moose-like sound can be caused on the exhalation by the exhaust valve(s). Again, this is just rattling and should go away under water.
A third sound, and one that is unique to DVT first stages like the EOS, is caused by the DVT system. When you first pressurize a DVT first stage, there is a huge pressure imbalance across the red DVT plug. This imbalance causes the plug to open and allows air to flow into the first stage from the tank. When the first stage locks up, the DVT plug closes up. It stays this way until you take a breath off the second stage. Once again, there is a pressure differential across the plug which forces the plug to open. The restricted opening in the intake causes air to hiss by the plug, and you can hear that. The restriction also makes the first stage slower to re-achieve lockup pressure, so the hiss continues for a second or so after you quit inhaling. I've had customers ask about the funny noise their reg makes underwater and I can duplicate it on the flow bench. I've had one customer request I take the DVT plug out of the reg, which I did. The noise went away. I think this noise is just the price one pays for having the DVT system on his reg. I've heard this noise off many Oceanic and Aeris regs, and I've seen a few DVT regs that don't make the noise at all. I'm not sure why some do and some don't.
None of these noises should be dangerous and you're not doing anything wrong. Just to be safe, though, if I were you I'd take my reg to the shop and verify with the service tech that the sound is benign and not indicative of something worse.
Hope this answers your question.
R
redacted
Guest
I had one that sounded like grandpa. I think it was the exhaust valve.
LeadTurn_SD
Contributor
keyshunter
Contributor
tfsails,
Are you saying that the DVT plug opens and closes with every breath? I was told that once it opens the pressure at the inlet holds it open, since it only requires about 15psi to hold it open. I have heard a couple of pretty loud DVT's underwater, and some that made no sound that I could hear. I talked to an Oceanic dealer who says he has removed several DVT's for people who are annoyed by the noise. One instabuddy I had was so annoyed by the noise in her Oceanic, that she rented a reg for the balance of her trip.
With the AL version, which is held open mechanically, I have never heard (or talked to anyone who has heard) a similar sound.
Are you saying that the DVT plug opens and closes with every breath? I was told that once it opens the pressure at the inlet holds it open, since it only requires about 15psi to hold it open. I have heard a couple of pretty loud DVT's underwater, and some that made no sound that I could hear. I talked to an Oceanic dealer who says he has removed several DVT's for people who are annoyed by the noise. One instabuddy I had was so annoyed by the noise in her Oceanic, that she rented a reg for the balance of her trip.
With the AL version, which is held open mechanically, I have never heard (or talked to anyone who has heard) a similar sound.
CT Sean
Contributor
Both my wife and I have Delta 4's with the FDX-10 w/ DVT first stage and neither make any noise. It is maybe interesting to note though that in it's first use after servicing last month, mine did make a couple goose-like honks (maybe similar to a moose sound?) but only on the first couple breaths and it hasn't made any noise since - perhaps it was just something that needed to settle in after servicing.
Out of curiosity, how do you have the breathing adjustment set?
Out of curiosity, how do you have the breathing adjustment set?
halocline
Contributor
Yes, the plug opens and closes with each breath. Once the pressure equalizes between the tank and the HP section of the reg, there is no pressure differential across the DVT crap (oops, I mean 'useful feature') so it stays closed. The IP drop on inhalation causes the pressure in the HP section to drop SLIGHTLY, which allows air to sneak past the plug into the HP section of the reg. It's not what I would call a good design; in fact since the tank valve is the bottleneck for air flow in any decent regulator, putting a restriction there is probably not the smartest idea. But it "seems" like a good idea when you're standing in the dive shop and the salesman can tell you about the horrors of water intrusion into the first stage. Welcome to marketing!
I would get it removed.
One small correction on tfsails post: I believe the resonance in the 2nd stage diaphragm that causes the honk is not between the diaphragm and the lever, it's between the diaphragm and the case.
Halocline says it pretty well. Those red plugs are great for marketing. They also hold pressure in the first stage if you haven't drained it before you take it off the tank valve. They look good, they will keep splashed water out of the first stage (and I really do think this was Aeris/Oceanic's intent when they devised it), but I'll be damned if I'd soak a reg sans dust cap with just that little spring-loaded red plug protecting my first stage.
kroorda
Contributor
It's absolutely the DVT valve. I finally removed my DVT valve and now ALL is well - and silent - as it should be underwater.
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