Snorkel cracking pressure?

[jdevic]

I cannot honestly recall when's the last time I actually used a snorkel...
I accidentally dropped the mares snorkel in my dive bag last week and the dry valve cracked open. It seemed to be very simple mechanism and I put it back easily.
Just to be sure, I tried it in the pool and I found it hard to breathe and took too much effort compared to my regulator. However, I doubt it was because of the valve because it shouldn't impact the air flow unless submerged.

Before I go buy another snorkel, is it completely normal that it is harder to breathe using a snorkel than reg?

 

[BRT]

Yes. That air up there is at a lower pressure than the air available at your second stage. Use a longer snorkel to get deeper and you will not be able to breathe at all.

 

[JackD342]

I cannot honestly recall when's the last time I actually used a snorkel...
I accidentally dropped the mares snorkel in my dive bag last week and the dry valve cracked open. It seemed to be very simple mechanism and I put it back easily.
Just to be sure, I tried it in the pool and I found it hard to breathe and took too much effort compared to my regulator. However, I doubt it was because of the valve because it shouldn't impact the air flow unless submerged.

Before I go buy another snorkel, is it completely normal that it is harder to breathe using a snorkel than reg?

Yes, expect a regulator to breathe better than a snorkel. In the regulator the pressurized air flows once you crack the valve. In the snorkel you have to suck the air down the tube against a few inches of ambient water pressure. Also, a dry snorkel usually does not breathe as well as a simple open top or semi-dry version.

 

[Bob DBF]

The pressure difference is between surface air and your lungs which are underwater, say 2 inches, and subject to that pressure. The cracking pressure on your reg is say 1 inch, so although these may not be accurate numbers, it gives you an idea of where the forces in play come from.

So the issue is your lungs being underwater, not the snorkel. Breathe through the snorkel out of the water and it will be easier.


Bob

 

[fmerkel]

And there is more dead space to overcome - the part of ventilation/breathing that does not take part in respiration/gas exchange. The longer the snorkel, the larger the dead space.

 

[The Chairman]

The pressure difference is between surface air and your lungs which are underwater, say 2 inches, and subject to that pressure.

I think it's actually the opening of your mouth, but I'm open to logic or info telling me differently. I did a test while floating at the surface where I varied the position of my mouth while trying to allow my chest to remain the same. The effort increased with the depth of my mouth. No, not scientific, but it's all I got.

As for those exhaust valves, water pressure will usually keep them closed while snorkeling. Seeing it have a bit of opening while on land doesn't mean it's broken. I usually touch the tip of my tongue on the roof of my mouth when I inhale. This ensures any water that intrudes will hit my tongue and prevent pharyngospasms caused by water hitting the back of my throat.

 

[Bob DBF]

Where’s @John C. Ratliff when we need him?



Bob

 

[scrane]

With double hose regulators they tell us breathing resistance depends on the level of the second stage (now behind your back) and your lungs. They hang their tanks very low so the yoke (and regulator) is centered between the shoulder blades.

 

[The Chairman]

The more I think about this, the delta pressure is statically indeterminate. Your chest and belly expand from the front and sides, not the rear, so the pressure on them determines how hard it is to breathe. It would be an average of the depth of muscles needed to breathe. Go from prone (on a snorkel) to supine and your breathing becomes a lot easier. It's opposite of being fully submerged with a reg in your mouth. In that case, the pressure on the first stage changes considerably from being below the chest muscles to being above them.

Technically, snorkels don't have a "cracking pressure" but a work of breathing.

 

[jdevic]

Technically, snorkels don't have a "cracking pressure" but a work of breathing.

LoL - you called it - I quickly realized it was inappropriate to call it "cracking pressure". but oh well people got what I meant.