Regulator not delivering enough air

[Sevenrider860]

It sounds like you were not happy with the flow rate of the previous regulator. Rather than two different regulators not being well tuned maybe the problem is the demands that you are putting on them. Are your dives high exertion ones? Are you a somewhat anxious diver?

Agreed. The Calypso, while not a high-end regulator in the Aqua Lung product line, should provide more than enough airflow.

 

[fmerkel]

I think your physics and notion of physiology are off. Out of the water you don't get air "shoved down your throat". The natural state of the lung is collapsed. You expend energy (diaphragm goes down, ribs go slightly out and up) and you SUCK air into your lungs. Then, (unless you deliberately blow out), when you relax the inhalation muscles, you exhale passively.
Try it and notice how it works.
The airways potentially can move a lot of air pretty fast if there is no obstruction or pathology. You have to, to be able to run a 1/4 mile in 60 seconds.

Unless tuned to free flow the reg simply sits there. Once cracked you still have to maintain some inhalation effort or it stops. That's how it's designed....or it would never stop. How 'easy' this is does depend on the reg and the tuning, but it is not the same as being out of water, and you actually aren't really breathing quite the same. The deeper I go, I take larger and slower breaths with longer and longer.....uh.....pauses. Don't confuse that with a breath hold (glottic stop). It's just a pause at full inhalation for a bit.
Pay attention to the exhalation. Since you have to open the valve and push the water away there is resistance there. One of the main reasons regs are so poor at bubble dispersion now is the exhalation cowling has been reduced to nothing to minimize exhalation effort. Makes them look better on machine tests. That is a fair part of the work of breathing, but people tend not to notice it. It's there...it is part of the balance.

Note - I've had dives when I have a low level of anxiety. The first real sign is a vague feeling of not getting enough air. When I pay attention to my breathing I realize that the actual mechanical breathing is just fine. Then I have to work on relaxing and getting into the dive and being distracted. If you focus on that feeling of not getting enough air for a whole dive even though you know you are fine it just fuels the anxiety.

I also get this same feeling when I'm down low and trying to see something that requires me to tilt my head way back and look up. That can stretch some nerves in the neck and provoke the same feeling of lack of air. Wearing a drysuit (neck seal) and doing that can pretty reliably produce that feeling in me. The seal may also block some of the circulation in that extreme position that contributes to the feeling. I back off and assume a normal diving position and it goes away.

 

[stuartv]

I know the regulator is well tuned (it free flows if I put it in the water on its back)

Even a poorly-tuned reg will do that. The difference is in how deep you have to put it under water before that happens. Tenths of an inch make a BIG difference. A good-breathing reg might free flow at 1.1" of water pressure and a poorly tuned one at 1.4". Being brand new means nothing, when it comes to being well-tuned. The factory might purposely tune it to a little higher cracking pressure just to reduce the number of complaints of brand new regs that are freeflowing.

Regulator Inspection and Checklist (Rev-7)

 

[Patoux01]

Being brand new means nothing, when it comes to being well-tuned. The factory might purposely tune it to a little higher cracking pressure just to reduce the number of complaints of brand new regs that are freeflowing.

Yeah, nah. The specs they are adjusted to at the factory are the same they are adjusted to after service. So unless you actually believe everybody tunes his own regs, a brand new reg is expected to deliver the claimed performances.

 

[tbzep]

I also get this same feeling when I'm down low and trying to see something that requires me to tilt my head way back and look up. That can stretch some nerves in the neck and provoke the same feeling of lack of air. Wearing a drysuit (neck seal) and doing that can pretty reliably produce that feeling in me. The seal may also block some of the circulation in that extreme position that contributes to the feeling. I back off and assume a normal diving position and it goes away.

I notice that when doing search patterns in zero vis. I have to hug the bottom and feel for it. I "look up" so that maybe I will see the log or object an inch or two before I hit it instead of bumping into it with the top of my head. With a standard regulator, the extra perceived effort isn't very noticible, but with my Guardian FFM, the effort seems substantial. It's partly because the regulator does require more effort than a normal regulator, but also because I'm craning my neck like you mentioned. The phenomenon isn't as pronounced in water with some visibility where I can stay a foot or two off the bottom and have a more normal head position.

 

[stuartv]

Yeah, nah. The specs they are adjusted to at the factory are the same they are adjusted to after service. So unless you actually believe everybody tunes his own regs, a brand new reg is expected to deliver the claimed performances.

That's a nice theory. In practice, I have bought brand new regs that came from the factory not tuned to breathe as well as what my service tech set them to after having them serviced.

 

[2airishuman]

OK that's not true, the regulator is providing me with enough air, I'm still alive after all but it feels like I'm not getting the same amount of air I would be getting if I breathed through my mouth on the surface without a regulator.

I recently bought an Apeks xtx50 regulator and one of the reasons I upgraded from my aqualung Calypso was the desire for a higher flow rate of air. I know the regulator is well tuned (it free flows if I put it in the water on its back) and I make sure that the adjustment knob and venturi is open all the way but I still feel like I could use more air shoved down my throat.

Thoughts?
Does anyone have a similar experience?

Right, so, I'm with the people upthread who state that you may have a problem with your reg. You may also have a problem with technique but we'll get to that.

You can take the reg back to where you got it and ask them to make sure it's adjusted right, or you can check it yourself. I use what I call the "sink-o-helic" test which is largely similar to the "bucket-o-helic" test others have described except it involves the use of the kitchen sink. I like my regs to be tuned right on the edge which means that they will start to open at 1" to 1.25" of vacuum. Utilizing the sink-o-helic method that means you submerge the reg slowly, with the diaphragm level, until it starts to open, and measure the distance between the surface of the water and the plane of the diaphragm. I use an actual ruler instead of eyeballing it. Run the test with the knob all the way open.

If it takes more than 1.25" of water to open the reg, then it needs to be adjusted by a technician for it to breathe really well.

The performance of new or newly serviced regs can drift with a little bit of use as the valve seats change shape. I service my own and I measure the breathing effort again and readjust them if necessary after the first couple of dives.

Now, if you establish that your regs are tuned properly, and you still have a problem, you may be overexerting yourself underwater, or too picky, or whatever, but I would start by making sure that the regs are set up right.

 

[fmerkel]

I just back off the adjustment until it ...just...barely.... leaks, then screw it back in just a 'smidgen' until it stops. Gets to the same place without the sink.
The one time I actually used a shop Magnehelic it leaked a week later when pressurized.Had to screw it back in a smidgen.

Agree that the reg tuning and function needs to be checked and adjusted first. Maybe letting someone with experience take the reg for a dive to be sure?

 

[Umuntu]

That's a nice theory. In practice, I have bought brand new regs that came from the factory not tuned to breathe as well as what my service tech set them to after having them serviced.

@Patoux01, I have had to return a set of new regulators which were very obviously poorly tuned two years ago.
My LDS returned them to the manufacturer, who handled it extremely well and had the problem corrected.

Poor factory quality control is at the heart of some of the manufacturer recalls

 

[Patoux01]

@Umuntu , that sounds very different of "every reg you buy has to be brought back for tuning".