Can different regs influence breathing rates?

[Potapko]

A friend of mine is trying to tell me that the reason he uses so much air is that his regulator is supplying too much. He says that with his previous reg he always had the lowest SAC rate .

I told him he was making excuses for being a HOOVER.

Thoughts?
Opinions?
FACTS?

 

[TheRedHead]

Does your friend's reg have an adjustable flow?

 

[wreckchick]

There are a couple reasons why a regulator might impact SAC rates, one would be if it's an overbalanced reg that's designed to SLIGHTLY overdeliver air. The other would be an unperforming reg that increases inhalation effort.

In neither of these cases would someone go from first to worst in air consumption, IMO.

YMMV,

Rachel

 

[redacted]

If getting "too much air" is increasing his anxiety level, then I guess it is possible. Usually it is the not enough air feeling that would cause that effect. Maybe you should make him an appropriate offer for the POS he regretably purchased.eyebrow

 

[cerich]

I've noticed a slight difference for my Sac between regs but only on the first dive with a new reg. After that all is normal.

Thats because I'm actually paying attention to my breathing which always causes an increased SAC.

 

[WarmWaterDiver]

If it's not in freeflow, I can't imagine the reg making a difference. The other extreme would be one that was completely insufficient, and no one would dive very long with such a rig.

This is not an excuse I've used for my gas consumption rate, but I have had DM's try to tell me I was using "too good" a regulator and would have lower gas consumption if I used their rental regs.

This could go on Penn & Teller's "BS".

 

[oly5050user]

A friend of mine is trying to tell me that the reason he uses so much air is that his regulator is supplying too much. He says that with his previous reg he always had the lowest SAC rate .

I told him he was making excuses for being a HOOVER.

Thoughts?
Opinions?
FACTS?

the easier the regulator is to breathe from the LESS air you use..you are using less effort to breath from a high performance regulator so your breathing rate will be slower.itas like on the old mk scubapro had,you leave the in line adjustment out for the easiest breathing,some people( newbies )screwed it in thinking they are conserving air because it was harder to breath-they are the ones always low on air first and short of breath upon surfacing..as long as it is not freeflowing it is fine..

 

[DA Aquamaster]

Generally speaking, people have higher SAC rates with regs that have higher inhalation efforts. The higher effort makes a more efficient deep breathing cycle harder to achieve. For that same reason, lower performing and harder breathing regs have the potential to cause higher levels of CO2 retention which in turn can increase susceptibility to nitrogen narcosis and oxygen toxicity.

The one situation where an easier breathing reg may cause higher air consumption would be if the second stage inhalation effort were set too light. In that case air leaking out the exhaust valve to equalize pressure inside and outside of the second stage can cause a slight but continuous freeflow during the pause between inhalation and exhalation. Many divers are not attuned enough to their breathing or listening for escaping bubbles enough to notice this slight air loss. This would be my suggestion for what is happening to your buddy with his new reg.

If his reg is adjustable, he needs to orient himself in a normal swimming position and listen carefully for air escaping out the exhaust valve after he stops inhaling and pauses before the exhale. A slight trickle immediately after pausing is normal as the pressure at the center of the diaphragm equalizes with the pressure at the top of the exhaust valve. But if it continues and/or if he hears a slight hiss of air entering the second stage it means the pressure drop in the case is enough to cause the diaphragm to rise enough to open the second stage poppet and allow more air to enter the second stage. This newly added air then leaks out the exhaust valve and the process continues as a very slight freeflow. The solution is to increase the inhalation effort slightly until the slight freeflow between breaths stops. If the second stage does not have an inhalation effort adjustment, he needs to take it to a tech to have it retuned.

Practically speaking, due to the case geometry fault inherent in most second stage designs, inhalation effort cannot be reduced below about 1.0 to 1.2 inches of water without encountering this problem in a face down swimming position.

The worst case postion for a conventional second stage design is face down with the diaphragm parallel to the bottom as this position usually results in the greatest vertical distance between the center of the diaphragm and the top of the exhaust valve. Consequently, this position requires the highest inhalation effort to avoid a slight freeflow. In a face up or vertical position, a lower inhalation effort could be used as the exhaust valve is lower or even below the center of the diaphragm and no air loss will occur.

 

[Potapko]

Does your friend's reg have an adjustable flow?

His reg is a Mares abyss. He is saying it causes him to use more air than his previous reg. His SAC rate is considerably higher than mine which is in the area of 17 L per minute.

Maybe the difference is who he is diving with. :14:

 

[Charlie99]

Generally speaking, people have higher SAC rates with regs that have higher inhalation efforts. The higher effort makes a more efficient deep breathing cycle harder to achieve.

That matches my experience. The Atomics B1 has a very low cracking pressure and very smooth delivery and works nicely for nice, slow, draaaaaawn out inhales.

With lower performance regs, my SAC goes up slightly.