Can a regulator breathe too easily?

[luis]

Can a regulator breathe too easily?

Yes, it definitely can.

Today, Christine and I went diving at Kettle Cove in Cape Elizabeth, Maine. The water temperature was adequate for diving wet, but we were both testing new stuff in our dry suit. I had a new neck seal and Christine was trying basically a new dry suit.

In addition, I was testing a Phoenix HPR with a new diaphragm. By just swapping the diaphragm, on the bench this regulator was showing a consistent and stable cracking effort of 0.3 inWC. I new that this was too low, for the cracking effort, but I just didn’t want to detune at this point. Well, that was a mistake.

First, both Christine and my dry-suit worked great.

The regulator breathed great in the swimming position, but every time I got on a vertical position it free flowed out of the exhaust due to the low cracking effort. The duckbill eliminator is centered right in front of the diaphragm. But, the valve is 1 inch in diameter.

That means the radius is 0.5 inches. Since the cracking effort is only 0.3 inWC, than means that the top edge of the valve in the DBE is 0.2 in higher in the water column than the center of the diaphragm when I am in the vertical position. This translates into a very predictable free flow when I am in a vertical position.

Well, normally this would not have been a problem in the normal swimming position, and that is why I didn’t bother to adjust the regulator before the dive.

With a dry-suit and a long shallow water (8 to 10 ft) swim back to shore… it is a problem. In shallow water it is much easier to squeeze the air out of the legs and vent by tilting slightly vertical. But every time I did that, I wasted a lot of air. A couple of times I saw my pressure gauge just drop 100 psi like nothing… that long shallow water swim was getting annoyingly longer. In a dive like this, I do carry a snorkel, but I don’t particularly like using it.

Anyway, this is an easy fix. There is absolutely no reason to have a regulator tuned to that low level. A 0.2 inWC difference in cracking suction can only be measure by a calibrated instrument… it is not something one can normally perceive.


Note: most modern single hose regulator have to be adjusted to a cracking effort of not less than 0.8 to 1.0 inWC (most to more than 1.0 inWC), due to case fault geometry. Case fault geometry it the term used to describe the distance from the exhaust to the diaphragm in a single hose regulator. In a diver inverted position, that distance will cause a free flow out the exhaust if the regulator is tuned too sensitive.

[ebj]

Luis
I sure am glad that I don't have to dive a drysuit here in the summer. I know if I had to deal with that case fault geometry and cracking suction on a dive, I would have to just give up and go home!
Thanks for the update!

[luis]

Yeah, well... you know... there is always golf...

[DaleC]

Luis, I had a similar sort of issue a month or so ago when I aggressively tuned my Mistral (ok, I just messed with it too much). On the bench I didn't notice and at the beginning of the dive it breathed so nice but at the end of the dive during the return surface swim (face forward, reg in mouth) I couldn't figure out why I was hyperventilating so much. Was I feeling anxious? Was I that out of shape (well maybe)? No, my reg was free flowing and inflating my lungs as soon as I exhaled. It took me till I was on the shore to figure it out.

I was also having a problem with my exhaust mushroom valve sealing onto my diaphram and getting pulled out of the DBE. I've since put a glob of silicone on the stem to hold it in place so we'll see how that works this weekend.

[Bryan]

I was also having a problem with my exhaust mushroom valve sealing onto my diaphram and getting pulled out of the DBE. I've since put a glob of silicone on the stem to hold it in place so we'll see how that works this weekend.

http://www.vintagedoublehose.com/index. ... t=11462520

[DaleC]

Thanks Bryan, I am going to get those next time I put an order through.

[luis]

Luis, I had a similar sort of issue a month or so ago when I aggressively tuned my Mistral (ok, I just messed with it too much). On the bench I didn't notice and at the beginning of the dive it breathed so nice but at the end of the dive during the return surface swim (face forward, reg in mouth) I couldn't figure out why I was hyperventilating so much. Was I feeling anxious? Was I that out of shape (well maybe)? No, my reg was free flowing and inflating my lungs as soon as I exhaled. It took me till I was on the shore to figure it out.

I was also having a problem with my exhaust mushroom valve sealing onto my diaphram and getting pulled out of the DBE. I've since put a glob of silicone on the stem to hold it in place so we'll see how that works this weekend.

Dale,
How do you aggressively tune a Mistral? The only adjustment on a standard Mistral is the lever height.
Did you measure the cracking effort? I have never measure the cracking effort of a standard Mistral to be below 1.5 inWC. Mistrals (and all single stage regulators that I am aware of) have a very strong venturi flow effect, but they are not known for a light cracking effort.

As I mentioned the cracking effort was 0.3 inWC. I detuned the regulator to have a cracking effort of 0.6 to 0.7 inWC. I will be testing it this coming weekend. With the exhaust valve having a 0.5 in radius, this detuning should be just right.

[Nemrod]

Not sure if it is cool to re-start this old thread but here goes. Just got the new super diaphragm into my Phoenix HPR. This regulator has made a bunch of dives this year at various depths and was doing just fine, smooth, solid, no issues. It has a single bleed port blocked, IP around 135. I put the new diaphragm in and found I needed to back the nut off about 1/4 turn or a bit more. Now it seems OK but a bit jumpy. Jumpy, like say my Tekna T2100. It will give that odd stumble when it pushes to much air and there is back pressure or feedback. The only other regulator I have come across that does this odd stumble is the SP Pilot. It is as if it is putting out more air than is being demanded which the Tekna T2100 was known for above 30 feet.

So, this has not been in the water yet and I am of a mind to leave it be as things often settle down in the water. The water can damp out some of the diaphragm bounce. Or should I:

1. Lower IP
2. Open the one blocked bleed to reduce the venturi effect
3. Add those shims
4. Or something else?

Any thoughts, if this needs to be a PM, feel free. The Phoenix HPR is beginning to behave like a for real high performance regulator, no longer just an idle brag, impressive.

Let me add, it was already pushing air to me at 100 plus feet, smooth but definitely pushing, which I really kind of liked and was not so noticeable at shallower depths. So pretty much perfect. The only change is the new diaphragm and backing the nut off a tad. It is probably OK, just needs to be dived.

Nem

[luis]

With the new diaphragm, I have found the issue to be more of an initial cracking effort, being too low, rather than a venturi issue. Therefore, I would adjust the IP or the second stage spring force and leave the bleed air alone.

I have fine tuned it (more like “de-tune” it) by either adjust the IP or adding the washers to the spring. At the end I always end up adding the washer so that the IP is up at the 120 to 135 psi range.

The bench mark that I use for detuning is that I don’t want the initial cracking effort to be less than 0.5 to 0.6 inWC. Anything lower than that, will cause the regulator to have a small free flow when I am in a vertical position or on my back.

With the new diaphragm (and no other change) I had to lower the IP of one regulator down to 90 psi, and another one to 110 psi. Both regulators performed great with that low of an IP, but I just didn’t like running a regulator with the IP that low. I like to run all my regulators at a similar IP so that I can swap octopus second stages, etc.

When I add the two washers (one on each side of the second stage spring), I can adjust the IP back up to about 125 psi and the cracking effort is just about 0.6 in WC.



The great thing is that during all these evolutions, the regulators have always been very stable and reliable. It is pretty amazing to have a regulator with a consistent cracking effort of 0.2 inWC to operate very stable with not even the slightest hint of wanting to leak on its own. It worked great in the swimming position, but it wasn’t so good in other positions. It was very predictable behavior and totally expected, but it is not very practical to have a regulator adjusted that low.

[DaleC]

Hi Luis, I don't know how I missed your earlier question. I didn't measure the cracking effort, I just adjust the levers.

I think I am developing some form of late onset asthma (according to the doc) because, if my WOB is too great I can develop a thick viscous phlem in my air way (gross) so I have been trying to reduce the WOB as much as I can.

It has been playing hell with my DH diving, fortunately my DAAM is an easy breather.

[Nemrod]

Thanks Luis. Just a quick note before I head out. I found the problem. You see, I guess staying up, drinking whine and watching the flat panel playing Prometheus is not conducive to precision work. Somehow I had inadvertently cranked the IP to around 150 . I have reset it to a more reasonable and for me typical 130 to 135 psi. It locks solid and there is no tendency now to bleed a little. Plus, the flutter is mostly gone and it feels much better. Hey, I dunno, I did not have my glasses on, uh, I was distracted, uh, anyways, I think it is OK now. I feel vibrations of goodness and love emanating from it's chrome cans now . If I have to, I guess, I will add those shims but only after a good water test first.

James

[antique diver]

.... I feel vibrations of goodness and love emanating from it's chrome cans now . ...
James

Hey James, can you say that with a French accent? It would sound kinda "Cousteau-ish"

[Nemrod]

OK, well, Luis, et al, just for reference, where are you guys taking your suction on your Magnehelic gauge. I am taking mine from a fitting between the mouthpiece and the can outlet, not, at the mouthpiece. I do this, right or wrong, to remove differences due to various cage valves etc. I thought this to be a more pure reading, only influenced by the diaphragm and mechanical bits?

So, my Phoenix RAM HPR is cracking at .4 inches. IP around 130 to 135. This of course is with the new "super flex" diaphragm. No shims installed. If I take the suction at the mouthpiece it is closer to one inch, maybe like .7 to .9. This is an old mouthpiece with the stiff neoprene cage valves, I just use it in my test rig.

One thing I notice is the strong venturi, as soon as the reg begins to flow at .4 inches, the suction actually drops off to near zero. This is only noticeable with the suction being taken from between the mouthpiece and the can outlet.

What is the wisdom on this, not sure I have ever head a reg flow at .4 inches before.

Nem

[antique diver]

Mouthpiece valves, and even the bare valve cage cause a noticeable increase in breathing effort. I really like the way my regs perform when I dive without the inlet valve... really smooth and open feeling. Try it sometime and you might be surprised at the difference in performance.

To eliminate the air resistance of the spokes in the cages(wagonwheels)I have completely removed the spokes from a couple of cages, essentially turning them into just a bare piece of tubing to support the mouthpiece tube.

I haven't run into any problems with this arrangement yet, but would like to hear from others that have tried this. Any problems clearing out the water, etc?

[Nemrod]

Mouthpiece valves, and even the bare valve cage cause a noticeable increase in breathing effort. I really like the way my regs perform when I dive without the inlet valve... really smooth and open feeling. Try it sometime and you might be surprised at the difference in performance.

To eliminate the air resistance of the spokes in the cages(wagonwheels)I have completely removed the spokes from a couple of cages, essentially turning them into just a bare piece of tubing to support the mouthpiece tube.

I haven't run into any problems with this arrangement yet, but would like to hear from others that have tried this. Any problems clearing out the water, etc?

Off topic, but, yes, without cage valves you can flood the can and will need to do the rolling clear. Yes, that is how I learned so long ago . The new streamline cages and silicone valves are nearly good as nothing so not sure going naked is worth the rest of it.

My second gen Phoenix Navy with gray non super flex diaphragm and HPR cracks at .7 inches.

My square label Royal, non-Phoenix with HPR and super flex diaphragm cracks at .4 inches.

My good old round label original phoenix with HPR and super flex diaphragm cracks around .4 inches.

Not sure what to think of regulators that crack to low, always had to struggle to get below 1.0 inches and now I am trying to get back, . Wow.

I think I am going to go with them at .4 inches------------???????

Nem