Inhalation adjustment knobs

[Bubbletrubble]

@Leadturn_SD: So I'm sitting here reading your last post...and it seems to make a lot of sense until I read the comment about a reg's tendency to freeflow until it's "flooded." I compose a quick post asking for clarification on that point...and then I see that the statement has magically disappeared. That's interesting.

With regard to cold water technique, I've read about not breathing your regs topside (due to cold topside temps) and not placing too much of a demand on the first stage underwater, e.g., not inhaling and inflating BCD/drysuit simultaneously. I had never heard about the necessity of an inhalation adjustment knob, so that's why I was asking. I do see the value in cranking down the cracking pressure a little to guard against a bump-and-flow situation.

By the way, I always enjoy reading your posts.

 

[Blue Sparkle]

I own regulators both with and without adjustable 2nd stages.

The advantages of adjustable 2nd stages are:

[1. and 2. removed]

3. The ability to store the regulator with the adjustment knob turned all the way out, which takes a bit of pressure off the soft seat and may prolong it's life a bit between services.

I hope I am not "hijacking" the thread to ask an additional storage recommendation question. (OTOH, if the OP is buying new regs, perhaps this will be welcome information in any case.)

I presume this information would not be specific to any certain regulator, but I happen to have a (recently purchased) Zeagle Flathead VI first, and ZX and Envoy seconds. The ZX has the cracking pressure adjustment knob and a "dive/pre-dive" venturi lever; the Envoy has just the lever.

I see that LeadTurn recommends turning the cracking pressure adjustment knob all the way out for storage (which is also mentioned in the Zeagle manual). Is there a more advantageous position for the "dive/pre-dive" venturi lever to be set to for storage? I don't see mention of that in the manual one way or the other. (If I were going to guess, I would think the "dive" position, but perhaps it makes no difference?)

Thanks,
B.S.

 

[LeadTurn_SD]

Bubbletrubble,

Lol.... you busted me!!!

I often type faster than my brain's "safe operating speed" And I am forced to quickly try to clean up the mess.

I re-read what I had typed, went "huh"???? And deleted it... but not fast enough

What I meant was that a well-tuned 2nd stage can have a tendancy to freeflow when out of your mouth, but should not once it is filled with water (pressure on both sides of the 2nd stage diaphragm will be the same, demand valve will remain closed).

Best wishes.

 

[Bubbletrubble]

I see that LeadTurn recommends turning the cracking pressure adjustment knob all the way out for storage (which is also mentioned in the Zeagle manual). Is there a more advantageous position for the "dive/pre-dive" venturi lever to be set to for storage? I don't see mention of that in the manual one way or the other. (If I were going to guess, I would think the "dive" position, but perhaps it makes no difference?)

@Blue Sparkle: AFAIK, the same thing (taking pressure off the soft seat) can be accomplished by storing the regs with the purge button slightly depressed. If you think creatively (channel your inner-MacGyver/MacGruber), you should be able to figure out how to do this with some sort of elastic material. In the end, though, we're talking about extending the life of a rubber seat that costs pennies to manufacture and a few bucks to order as an OEM part.

Edited later: I was going to add that Venturi lever position shouldn't affect wear on the low pressure seat...but as usual LeadTurn beat me to it. AFAIK, the Venturi effect (as applied in regs) supports the persistence of flow once initiated. Putting it in the pre-dive or "negative" position directs flow so that it doesn't have a tendency to support persistent flow.

 

[LeadTurn_SD]

Hi Blue Sparkle,

The venturi control lever on the Zeagle ZX 2nd is actually part of a plastic "tube" that rotates around the valve tube to enable or disable the venturi effect.... it does not effect the pressure being placed on the soft seat in the demand valve, so no, I don't think it's position matters at all as far as storing the reg. I think I just set mine to the "-" (predive) position since that is where I want is set at the start of my next dive

By the way, the Flathead VI is a wonderful regulator. It is the easier to service than my Mares first stages (and that is saying a lot, because the Mares regs are very easy to work on), and has been a rock solid reg (I have two of them).

Best wishes.

 

[SangP]

My experience with the cracking pressure valve is that it does make a difference.

With the valve closed my wob is about 2 and with it fully open it goes down to about 1 (this is on factory settings).

Although it's true that a properly adjusted reg should not free flow, in dives where there are strong currents, I prefer to detune the reg but be able to adjust the reg while underwater to breath easier when possible.

The valve does make a difference.

SangP

 

[Blue Sparkle]

By the way, the Flathead VI is a wonderful regulator. It is the easier to service than my Mares first stages (and that is saying a lot, because the Mares regs are very easy to work on), and has been a rock solid reg (I have two of them).

Best wishes.

Thank you (and Bubbletrubble) for the information on the venturi lever. I see what you mean about how it probably will not make a difference when stored; so as you say, might as well put it where you would want it for the next dive.

I received the Flathead VI as a gift just before my last dive trip - it's my first reg. Sure is nice to have my own! I would like to learn more how it works and potentially be able to service it myself, so it's nice to read that it is solid and (relatively) easy to service.

To keep this from being a total hijack, I'll say that I found that adjusting the cracking pressure knob during a dive *seemed* to help reduce the dry mouth I was getting - although that may just be because I had it mis-set to begin with (an experienced diver said to just turn it wide open, so I started with it there - but that seemed a bit "forceful" and I was getting really dry mouth/throat). So now having said that, maybe the dry mouth/throat would not have been a problem on a regulator without the knob, because I would not have had it "wide open" to begin with (or if I had not had the knob all the way open).

'twas all better than rental regs though, IMO

Blue Sparkle

PS: One more note: I'm not sure if it works this way with Aqualung, but with the Zeagle regs you can have the adjustment knob added later if you bought one without and change your mind. In their case, it's $24.99 if you have it done while your reg is being serviced.

 

[redacted]

Thank you (and Bubbletrubble) for the information on the venturi lever. I see what you mean about how it probably will not make a difference when stored; so as you say, might as well put it where you would want it for the next dive.

I received the Flathead VI as a gift just before my last dive trip - it's my first reg. Sure is nice to have my own! I would like to learn more how it works and potentially be able to service it myself, so it's nice to read that it is solid and (relatively) easy to service.

To keep this from being a total hijack, I'll say that I found that adjusting the cracking pressure knob during a dive *seemed* to help reduce the dry mouth I was getting - although that may just be because I had it mis-set to begin with (an experienced diver said to just turn it wide open, so I started with it there - but that seemed a bit "forceful" and I was getting really dry mouth/throat). So now having said that, maybe the dry mouth/throat would not have been a problem on a regulator without the knob, because I would not have had it "wide open" to begin with (or if I had not had the knob all the way open).

'twas all better than rental regs though, IMO

Blue Sparkle

PS: One more note: I'm not sure if it works this way with Aqualung, but with the Zeagle regs you can have the adjustment knob added later if you bought one without and change your mind. In their case, it's $24.99 if you have it done while your reg is being serviced.

If the air is too "forceful" (usually referred to as positive pressure breathing), use the venturi adjustment to reduce the force rather than the cracking pressure adjustment. The cracking pressure knob regulates how much work is required to start the gas flowing. That flow kicks in the venturi effect which works sort of like a siphon, pulling the gas through the 2nd stage toward the mouth. The venturi adjustment then controls the amount of interference with that flow. So, if you are getting too much positive pressure breathing (gas being forced into your mouth, use the venturi adjustment to increase the interference and turn that down a bit.

 

[Jimmer]

Ok, I'm going to try to clear up a few things about my post. First off, I never stated that the Alpha 8's were not cold water capable. In fact I have used them under the ice and came back alive My issue is strictly with the non adjustable second stage. I just don't like them. I do my own service, and am actually an approved Oceanic/Hollis/Aries reg tech for my shop.

I originally had them both setup to breathe the same, but had the necklaced reg occasionally free flow. Nothing that a quick tap, or turning it mouthpiece down wouldn't fix, but a nuisance. So I chose to detune it a touch, just enough that it was very slightly noticeable during an S drill or random reg check. What was noticeable was when I had a panicked diver on the end of my 7 foot hose at 125' deep, and under a bit of stress myself. It wasn't like I was being choked for air, I was quite alright, but it was very noticeable that all of a sudden, my reg wasn't acting the way I was used to.

I have nothing against Oceanic or those regs. I used them quite happily in San Andres, floating along nice coral reefs, and when I sold them, I only sold the second stages, and those first stages are now equipped with adjustable Oceanic GT3 second stages that my wife and I use for single tank diving.

Overall, I just personally prefer the adjustable second stages for versatility, and I don't really buy into the whole thing about them being way more complicated than non adjustable second stages. Essentially all the adjusters do, is add some preload to the second stage seat. Nothing that is going to catastrophically ruin your day.

Hope that clears things up,

Jim

 

[Lineman Larry]

Back to the OP scuba393...

As you can maybe gather from the discussion, a lot of you satisfaction will get down to how your regs are tuned. ie: you reg tech.

I happen to own an older version of the non-adjustable regs you are considering. The adjustable version is not any more complicated. The difference for that specific part of the regulator is that one has a knob and the other must be adjusted with an allen wrench under a plastic cover.

I have had those regs at 130+ feet in 35 degree water and now I dive the warm waters of Florida. My non-adjustable regs breath just as smooth as I could ask and I would buy them again. However, I take care of my own regs and I can set them up any way I want them.

Think about this: If your LDS is going to service your regs for you, you might want to buy the adjustable version.