Correct usage of Venturi effect lever

[BoltSnap]

All the complaints about water potentially getting in the hoses when you soak the regs unpressurized are (IMO) FAR OUTWEIGHED by the benefit of taking the poppet off the orifice during storage. You just soak your second stage in the sink and leave the first stage on the counter, if you can't soak it pressurized. Then soak the first stage while the second is on the counter (but make sure the intake is plugged, of course).

I am not sure of how water can get in if there is air in the hose under atmospheric pressure. You can also put the two stages in the water at the same time and at the same level but the hose connecting the two rise up in the water eliminating any chance of water traveling from the second stage to the first (it can't anyways since there is air in the hose and the pressure on all sides is the same).

Yeah, I think the seat saver feature is great. When I service my Atomics, the poppet seat is almost completely unaffected by the orifice at the 2 year mark.

It certainly is making Atomic regulators some of the most reliable trouble free regulators out there.

 

[halocline]

I am not sure of how water can get in if there is air in the hose under atmospheric pressure.

It can happen if the 2nd stage is soaked at less depth than the first stage. Water displaces the air in the hose, which leaks out the 2nd stage. Whether or not it reaches the 1st stage would depend on how the hose was sitting in the tank.

I always blow some air through my regs after soaking them from a tank to make sure there's no water in any of the hoses.

 

[Sbiriguda]

The Venturi Switch Effect and Scuba Diving

I also found this link, which I found informative. It also has a basic explanation of Venturi effect physics in regulators

 

[BoltSnap]

It can happen if the 2nd stage is soaked at less depth than the first stage. Water displaces the air in the hose, which leaks out the 2nd stage. Whether or not it reaches the 1st stage would depend on how the hose was sitting in the tank.

I think that was explained in the next sentence in my comment:

You can also put the two stages in the water at the same time and at the same level but the hose connecting the two rise up in the water eliminating any chance of water traveling from the second stage to the first (it can't anyways since there is air in the hose and the pressure on all sides is the same).

I always blow some air through my regs after soaking them from a tank to make sure there's no water in any of the hoses.

Always do that but I think one should also remove the gauge hose and put a port plug in its place first to be sure that no water is blown into the HP hose and the gauge.

 

[Neilwood]

Have to say reading all the posts above has been quite informative as, since purchase I have tried various settings on my S600 and never noticed much of a difference with any of them.

 

[Grey Goose]

I recall a few years back I was diving my Apeks reg with the lever all the way open and the knob all the way open. I seemed to go through air really quickly on this 30 foot dive. Does having the knob wide open explain this, or is it the lever, or does neither knob or lever affect the amount of gas one blows through.

 

[BoltSnap]

I recall a few years back I was diving my Apeks reg with the lever all the way open and the knob all the way open. I seemed to go through air really quickly on this 30 foot dive. Does having the knob wide open explain this, or is it the lever, or does neither knob or lever affect the amount of gas one blows through.

Having the venturi on and the cracking effort adjustment knob open all the way open by themselves won't cause loss of air as long as there are no other issues, they certainly won't effect "the amount of gas one blows through" at all. If the diver takes the second stage out and the venturi is still on and the second stage free flows or any other unusual issue, this would cause rapid loss of air due to free flow. If all is good and according to proper use, they will actually reduce the breathing effort require to open or to keep the valve open and thus less stress on the lungs leading to more relaxed breathing and less air consumption not the other way around.

 

[kelemvor]

It certainly is making Atomic regulators some of the most reliable trouble free regulators out there.

Are there other brands of regulators failing because of this even when the owner follows the recommended service interval? Incompetent service people notwithstanding, I would think the part would get replaced during a service before failing, no?

 

[rsingler]

Are there other brands of regulators failing because of this even when the owner follows the recommended service interval? Incompetent service people notwithstanding, I would think the part would get replaced during a service before failing, no?

It's not so much "failure" as it is the poppet seat acquiring a groove ("taking a set") that then allows the second stage to freeflow a little. When that happens, a typical diver may indeed think, "my reg is failing", or "my reg had lousy service. Look - it's freeflowing already!"
If you service things yourself, you know that it's a five minute re-tune, by adding 1/24th of a turn on the orifice, and bingo! Freeflow gone.
But now much nicer to have a seat that hardly takes a set, and never seems to need tuning in between service intervals! That's what seat saver regs allow.
The way shops avoid this problem with ordinary brands and most divers, is by handing you a reg that is tuned to the top of the allowable cracking effort. It breathes stiffly (if you are trained to feel the difference), and to me that is just wrong! But most divers don't know the difference.
The advantage that tuning stiff offers the shop is that as the poppet seat takes a set, the cracking effort drops bit by bit, and the reg gets easier to breathe. But it doesn't take enough of a set in one year to freeflow before the next service is due.

I'd rather have a reg that breathes soft and easy (bottom of the cracking effort range), with a mechanism that allows the seat to stay as good as new, for not one, but two or even three years.

As discussed above, we used to teach divers to take the pressure off the seat by inserting the "key", or pressing and locking the purge button "in" during storage, on those regs that have the feature. But that is uncommon knowledge, these days.

If a diver comes in asking to have his reg tuned "really light", we talk about the possibility that it may freeflow a little 3 months from now. We talk about using the adjustment knob to increase spring tension and (maybe) save the dive before he/she brings it back for tuning. And we definitely talk about ways to take pressure off the seat with the purge button during storage. But it is the RARE diver that has a specific cracking effort request.

 

[BoltSnap]

Are there other brands of regulators failing because of this even when the owner follows the recommended service interval? Incompetent service people notwithstanding, I would think the part would get replaced during a service before failing, no?

With other brands, the main issue with second stages is the seat that makes the second stage leak. With Atomic, the second stage is designed so that the seat would last a lot longer and can take many more years of use before needing service. My Atomic ST1 hasn't been serviced at all since 2012 and it has never had any issues whatsoever despite of the MANY dives I have put on it since 2012. I have several other Atomic regulators that have no issues at all but they aren't as used or old as my ST1. I have other brands in my training fleet that don't come close in reliability or trouble-free use as the Atomic (Cressi and Mares come to mind here).