Reg seems to breathe harder when looking up?

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ChrisA:
When looking up the diaphragm is on the top of an airspace. The air wants to float up and pushes the diaphragm upward and away from the mouth. This is the same direction the diaphragm is pushed when you exhale it closes the demand valve.

At the surface you can make some regs freeflow simply by holding then mouthpeice up and you can prevent that by holding them mouthpeice down.


Yes, is this freeflowing when up a sign of a problem or normal? My reg does it.
 
pescador775:
I don't see how anybody can claim with a straight face that a single hose regulator breathes the same when the diver is inverted and/or vertical. It is indisputably true that all single hose regs breath harder in the vertical position, regardless or diaphragm positioning, and that this is due to the position of the divers lungs WRT the second stage. It is true that a second stage will free flow when removed and in the mouthpiece up position. That is caused by the second stage venturi and this device is actuated by the first bubble which leaves the mouthpiece. It can be quickly stopped and will not restart if the regulator is flooded. Once the mouthpiece is evacuated and filled with air, in the mouth and isolated from the water column, the effect is cancelled and only the diver's inhalation will restart it. If the pressure differential due to the shape of the mouthpiece were significant then, the instant the mouthpiece were removed, the free flow would not stop, it could not be stopped. No diver is that sensitive to pressure gradients such that he could detect a force differential equivalent to a quarter inch of water column which is what it amounts to. It's mental.


Why would double hose setup be any different from single hose?

And to a previous question, yes I mean hard inhalation resistance when looking up. I noticed this effect while in a pool, so do not know if it is the same at depth.
 
John C. Ratliff:
H2Andy,

I will bet that, when you think you are swimming supine (face up) that you are actually somewhat off the horizontal plane. You will probably not be horizontal, but have your head quite a bit higher than your lungs.
SeaRat


I originally noticed the resisitance while my body was vertical and my head was looking straight up to the surface as opposed to vertical and looking straight ahead. In my case the reg purge button was facing the surface or 'up' in position.


Thanks for all the replies!
 
allenwrench:
Why would double hose setup be any different from single hose?

And to a previous question, yes I mean hard inhalation resistance when looking up. I noticed this effect while in a pool, so do not know if it is the same at depth.

A double hose differes from a single hose in that a single hose reg has two stages and the second stage is in your mouth. With the double hose reg, the whole reg is behind your head by the tank valve and all that's in your mouth is a mouth piece.
 
AllenWrench,

Concerning the double hose regulator, I posted this link before on this thread:

http://vintagescuba.proboards2.com/...ction&action=display&thread=1071971414&page=2

Please go back and read it fully, and you should know the answer then. Sometimes to gain knowledge, you need to do a bit of homework.

Concerning your perceptions of this regulator, I have no further answers. I think you need to do more trials, and make sure you understand have correctly defined the physical situation. If so, then you have something unique.

SeaRat

PS--ChrisA's explaination is only correct if the regulator and the diver's mouth are filled with water, and a small air bubble is inside the regulator pushing up. But then, breathing air under these circumstances is not possible. Rather, what's happening is that the difference between the top of the diaphragm and the non-return valve affects exhalation resistance just a little. Inhalation resistance would be measured from the top of the diaphragm to the center of the lungs.
 
Funny you mention it, I was messing with this last weekend, I noticed that my XTX50, ATX50 and SeaAir Trimetal all do this....but, a friends Atomic B2 doesnt...this might vary with depth.
 
A short tech note of interest to some, perhaps. It has been established that the inhalation resistance of a single hose reg varies with attitude, easier when the head is down and harder when up. This variation is mostly a function of the height differences of the demand valve (mouthpiece) to the chest. The same water pressure which acts on the diver's chest, making it easier or harder for the diver to expand his chest, affects not only inhalation resistance but also impairs or promotes exhalation equally. Thus, an increased force pressing on the divers chest makes inhalation more difficult and will simultaneously make it easier to expel air. Exhalation is the opposite of inhalation, thus, when it is harder to inhale it is also easier to exhale, by approximately the same measure.
 
Body position in the water has a great bearing on breathing effort!

A simple way to test this is to try it without a regulator.
Use your snorkel instead, in a normal face down position, with no weight belt, so that your chest is not pulled down at all.

Compare that experience to breathing, while you deliberately sink your lungs to the lowest level possible. This will be leaning back and looking up. You will probably need a weight belt to do this, but be sure to keep it low on your hips so you do not restrict your diaphragm. You will have to hold the snorkel with the tip held up out of the water, easiest to do without it attached to your mask.

This test can be done with no snorkel too, but obviously not having a blow hole, you have to lay on your back and keep your lungs at the highest possible point, maybe by holding onto a float if you are negatively buoyant. We often do this when freediving to get a really good breathe-up, without the dead air space of the snorkel.

There is quite a difference!

Of course water pressure is why long snorkels don't work. Breathing is very labored at about 2 feet and you can't breathe at all much past that depth. (Figuring that your chest has about a square foot of area, 144 square inches, and there is about a 1/2 psi change in pressure per foot... it feels about like there is an extra 144 lbs sitting on your chest while you breathe at 2 feet!)

Regulators are designed to work best when in a normal horizontal position, where the divers chest is close to level with the second stage. On your back, while tilted back and looking up, there is about one foot of water pressure difference. (About like an extra 72 lbs on your chest that your regulator is trying to overcome.)

There are many air flow characteristics that will make a noticeable difference with various second stages, such as internal volume, diaphragm position, breathing tube volume and placement, and venturi devices. If on your back or looking up at great depth, the density of air can also aggravate these regulators ability to perform.

No regulator can breathe equally well for a diver with his chest level well below the second stage, as it does when at the same level.

The trouble here is in the measuring.

Chad

FL Zeagle Rep.
 
allenwrench:
ArcticDiver:
.

The Zeagles I used for a few dives breathed very wet when inverted; like a whole mouthful of water.

(QUOTE]



What do you mean, 'like a whole mouthful of water'.
Do the zeagles work poorly inverted?

Obviously this is not the case. Our regulators have been shown to be very dry in many tests. Any regulator would have to have it's exhaust valve cocked open or punctured to get a whole mouthful of water.

Obviously dryness is a subjective subject.

Scuba Diving Magazine, from the Muscle Regs article, Nov 2005... "In real world diving both regs, (Flathead VI & Flathead XP), proved to be very easy breathers in all positions. They also breathe dry, even after clearing, thanks to a very efficient purge system." (BTW, we had not advertised with them in over 3 years, nor told them we would start again.)

And here's another recent review of our DS-V, by 4 guys. I have no idea who they are, but they don't seem to mind slamming a product if they don't like it. http://www.divester.com/2006/08/27/15-regs-at-150-feet-compared/

By the way, all our second stages are identical with any factor that would effect dryness. Do a search on this board for many more opinions.

Chad

FL Zeagle Rep
 

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