2nd stage issue?

[amclaughlin200]

Yes it's about diver preference

https://www.hollis.com/media/wysiwyg/HO/manuals/Hollis_Reg_Owners_manual_HO.01.05.0001_10-12-2017.pdf

https://www.scubadoctor.com.au/downloads/regulator-manuals/Hollis_Regulators.pdf

So it’s free flowing at the surface after purging it? You have a very lightly tuned regulator… increased pressure at depth or obstructing the mouthpiece opening will prevent or stop the flow.

Nothing wrong with it unless you can’t stop the free flow with increased pressur

Yes it's about diver preference

https://www.hollis.com/media/wysiwyg/HO/manuals/Hollis_Reg_Owners_manual_HO.01.05.0001_10-12-2017.pdf

https://www.scubadoctor.com.au/downloads/regu

[QUOTE="happy-diver, post: 103927...lator-manuals/Hollis_Regulators.pdf [/QUOTE]

M

Less work of breathing means breathing muscles are working less, less energy spent, and a lower gas consumption. High WOB can lead to deficient ventilation, causing a CO2 build up, so depending on your depth, the density of the gas and your workload, you should be careful of artificially raising the WOB.

In general, lower WOB is

Less work of breathing means breathing muscles are working less, less energy spent, and a lower gas consumption. High WOB can lead to deficient ventilation, causing a CO2 build up, so depending on your depth, the density of the gas and your workload, you should be careful of artificially raising the WOB.

In general, lower WOB is better.

She is doing it right, you are doing it not so right.



Don't, she is doing it right.



It appears to be doing what it was designed to do, no issues.

I think that it is working as it should. When the knob is out all the way and the venturi is on and you press the purge button it will let air out and will continue to do that until you put your finger/thumb on the mouthpiece opening to stop the venturi effect and the freeflow should stop. It is supposed to do that by design.

When you are diving, you should have the adjustment knob on full +, open all the way out, and venturi on. As long as the mouthpiece is in your mouth, adjustment knob should be all the way out and venturi on full on. The only time you turn the knob back is if there is air leak when you are breathing from the second stage. You turn the knob back just to stop the leak. When the regulator mouthpiece is out of your mouth, the knob should be turned in and venturi off.

"High Flow Setting -
• When diving deep or during other periods of heavy exertion, it is desirable to
make the 212 breathe as easy as possible. This setting should be used only when
necessary to avoid loss of air that may occur due to the 212’s extra sensitivity at
this setting.
• To adjust the 212 for minimum breathing resistance, rotate the adjustment knob
'counter clockwise' until a slight flow of air begins, then rotate the knob
'clockwise' until the flow stops.
• Frequently monitor your air supply when the 212 is adjusted for maximum flow."

At least you inspired me to fully read the manual. Hollis doesn't want you diving it fully open unless needed/specific conditions. Where is the idea coming from that you just dive full on no matter what? I'm not restricting my breathing by turning the knob down a bit. It's more comfortable because I don't like when the regulator feels like it's forcing air into my mouth. If it's your preference to dive with it completely open then I get that. But you said I was "wrong."

 

[Pbdiver84]

http://

M




"High Flow Setting -
• When diving deep or during other periods of heavy exertion, it is desirable to
make the 212 breathe as easy as possible. This setting should be used only when
necessary to avoid loss of air that may occur due to the 212’s extra sensitivity at
this setting.
• To adjust the 212 for minimum breathing resistance, rotate the adjustment knob
'counter clockwise' until a slight flow of air begins, then rotate the knob
'clockwise' until the flow stops.
• Frequently monitor your air supply when the 212 is adjusted for maximum flow."

At least you inspired me to fully read the manual. Hollis doesn't want you diving it fully open unless needed/specific conditions. Where is the idea coming from that you just dive full on no matter what? I'm not restricting my breathing by turning the knob down a bit. It's more comfortable because I don't like when the regulator feels like it's forcing air into my mouth. If it's your preference to dive with it completely open then I get that. But you said I was "wrong."

http://

M




"High Flow Setting -
• When diving deep or during other periods of heavy exertion, it is desirable to
make the 212 breathe as easy as possible. This setting should be used only when
necessary to avoid loss of air that may occur due to the 212’s extra sensitivity at
this setting.
• To adjust the 212 for minimum breathing resistance, rotate the adjustment knob
'counter clockwise' until a slight flow of air begins, then rotate the knob
'clockwise' until the flow stops.
• Frequently monitor your air supply when the 212 is adjusted for maximum flow."

At least you inspired me to fully read the manual. Hollis doesn't want you diving it fully open unless needed/specific conditions. Where is the idea coming from that you just dive full on no matter what? I'm not restricting my breathing by turning the knob down a bit. It's more comfortable because I don't like when the regulator feels like it's forcing air into my mouth. If it's your preference to dive with it completely open then I get that. But you said I was "wrong."

In general for regulators with adjustments, the “full open” is the setting the service manuals aim for. It is a common bad habit for divers to then crank the knobs way down to prevent any possibility of freeflows (instead of positioning their regs properly) or try to conserve gas.

For these regs, the factory is saying tune them for high demand deep conditions, then adjust for actual dive conditions. You should still be able to get them breathe easily if you adjust the knobs properly

 

[Nemrod]

I looked through the Hollis SM and there is nothing unusual in the adjustment that would indicate the need to back the regulator down during normal use. Adjustment of the second stage during service is straight forward. Second stage SM attached.

If during a dive a second stage leaks slightly or wants to free flow with the adjustment knob fully out then by all means turn it in enough to stop the leak. Some people will during service tune their second stage to a "hot" tune such that it leaks with the knob fully out in which case during normal use the knob will need to be turned in slightly.

The Hollis 212 Owner Manual instruction does not convey the intent clearly. Rolling the adjustment knob in beyond what is needed to stop free flow tendency or (nuisance) bubbling/leaking for personal preference during a dive is bad advice and will increase the WOB unnecessarily, increase air consumption and lead to diver fatigue all of which can have bad outcomes.

 

[BoltSnap]

What is the reason for not diving with the adjustments partially closed?

Why do you want to make it harder for your lungs to breathe? Normally, people want their regulators to deliver air to them at the lowest effort possible (without leaking air of course). There is no benefit to making it more difficult to suck air/gas in, none at all (except if your second stage is leaking air due to improper adjustments by technician or issues with seat).

You're telling me this is a 100% wrong way of diving?

You can dive any way you want, there are no scuba police checking your cracking pressure adjustment knob AFAIK. It isn't optimum way of doing it nor an efficient or necessary way (except to stop air leakage from second stage but just enough to stop the leaking).

It has nothing to do with diver preference?

Stopping air leaking due to improper internal adjustments by technician, seat wearing out or too high IP. All these issues need to be addressed by a qualified technician upon coming out of the dive.


Making it more difficult to draw air out of the regulator unnecessarily will only make your lungs work harder, building up CO2 level in your body (which is bad) and increasing potential safety hazards. Even if you don't notice that your lungs are working hard during the dive, it isn't a good thing. I frequently hear divers complaining that they have chest muscle pain after they come of their dive and with tracing their story it usually turns out that their regulator second stage has cracking pressure higher than acceptable range.

In summary, no one should make it more difficult for themselves and lungs to work hard than they have too at all. Their regulator should deliver air at minimal effort (without leaking air). Regulator manufacturers compete against each other on who comes out with the least effort regulators among other features btw.

 

[Nemrod]

I have not seen enough information to understand or to even know if pulmonary edema is a real possibility due to high inspiration effort. But, if I use a "particular type of regulator" that has a high inspiration effort over the course of several days and numerous dives I get a cough and difficulty breathing as if I cannot get a full breath during and afterwards (and as a competitive swimmer):

What is swimming-induced pulmonary edema?​

Immersion pulmonary edema is sometimes called swimming-induced pulmonary edema. It occurs when competitive swimmers and divers develop lung injuries because their lung capillaries burst. During diving, blood is sent to your lungs from your legs and abdomen. That excess blood increases pressure in the blood vessels of your lungs. The vessels leak, and the fluid goes into your air sacs.​

I am not sure or convinced but it may be possible over the course of a number of long dives that fluid (blood) could accumulate in the lungs due to a high inspiration effort? SCUBA (negative pressure) regulator high inspiration effort induced pulmonary edema? Yeah, just go ahead and roll that adjustment knob tight so that no air is wasted breathing. I do not know enough to ascertain the possibilities but restricting purposely inspiration demand does not seem like a good idea to me.

And when scuba diving all sorts of stuff is going on in your lungs as you take on nitrogen and then off gas that nitrogen. How would the possibility of CO2 retention, diver fatigue, fluid in the lungs affect off gassing the nitrogen load?

 

[rsfinn57]

there is a well documented phenomena of negative pressure pulmonary edema but that requires inhalation against an obstruction. It is not associated with burst capillaries but certainly can be life threatening. I have only seen this when conscious or semiconscious patient is on a mechanical ventilator

 

[Nemrod]

there is a well documented phenomena of negative pressure pulmonary edema but that requires inhalation against an obstruction. It is not associated with burst capillaries but certainly can be life threatening. I have only seen this when conscious or semiconscious patient is on a mechanical ventilator

Thanks for that. What I read, there were a couple of papers, one concerning full face snorkels and another concerning competitive swimmers, I thought I had them here, anyways. My question, not a statement but a question, can turning the regulator to Pre-dive setting (reducing or stopping Venturi-VIVA assist) and then dialing in on the adjustment knob essentially a higher cracking effort (above the SM settings typically 1.0 to 1.6 in/water, so then say 2.0 to 4.0 inches) cause edema over numerous dives, say a multi-day, multi-dive per day interval?

 

[happy-diver]

Have to be better than breathing too much pressurised cold air tearing through your throat and out your...

 

[Pearlman]

"High Flow Setting -
• When diving deep or during other periods of heavy exertion, it is desirable to
make the 212 breathe as easy as possible. This setting should be used only when
necessary to avoid loss of air that may occur due to the 212’s extra sensitivity at
this setting.

I believe the manual is alluding to a design characteristic of this regulator that makes it easily prone to free flow once correctly tuned if some conditions are met, for example facing into high flow current, using a water scooter etc.,

This may be due to various design factors like length of the effort arm vs load arm of the demand lever and the resulting mechanical advantage, the stroke range and the resulting amount of seat separation typical with a well tuned regulator of this model giving it a high flow…

there is a well documented phenomena of negative pressure pulmonary edema but that requires inhalation against an obstruction.

There was snorkeller death in the recent past at Hawaii blamed on ROPE. IIRC going through a linked document on that thread - for this to occur many conditions have to be met (aligning the cheese holes) that increase the likelihood including but not limited to:

• A 5+ hour flight in a cabin pressurised for 8000 ft that change the lung performance with regards to diffusion of gases and fluids in the capillaries - within the last 24 hrs
• Breathing through a narrow restriction like a snorkel

The casualty in that case met at least both these parameters besides one more significant attribute - being above 50 and perhaps not in the best of health and fitness levels….