scrane
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Air Consumption - Double Hose

Sat Jan 18, 2020 12:16 pm

I wonder if experienced Double Hose regulator users can offer some opinions on relative air consumption of single vs double hose regulators? After many years of diving single hose I am at a point where air consumption is not a real concern for me. Since my experience with double hose is limited so far to swimming in small circles at 12' in a swimming pool I cannot judge how fast I am going through air.
At normal depths of say 40' - 100' will I notice an increase in my air consumption to an appreciable extent?
Thanks for your comments.

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Herman
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Re: Air Consumption - Double Hose

Sat Jan 18, 2020 12:53 pm

I can't tell any real difference but then again I have pretty much dove DH for the last 5-10 years. Lung volume is the same and air density is the same so I can think of no reason that there should be a difference assuming equal skills and conditions. My diving ranges from shallow to over 100ft, I have taken DHs to 130 on occasion. I know others have done deep deco dives on them.
Herman

scrane
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Re: Air Consumption - Double Hose

Sat Jan 18, 2020 1:07 pm

Thanks, Herman.
I was thinking that the variation of breathing effort might have some effect. Also possibly air shooting directly from the input to the output hose , bypassing the lungs. I think I heard mention of a baffle being incorporated into the DSV to reduce this effect.

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ScubaLawyer
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Re: Air Consumption - Double Hose

Sat Jan 18, 2020 1:51 pm

Unless you have your venturi intentionally cranked up there should be no issue of blow-by. I go back and forth between single and DH for varying purposes, mainly DH. Never noticed an increase in air consumption. My 2psi.
"The diver who collects specimens of underwater life has fun and becomes a keen underwater observer. .. seek slow-moving or attached organisms such as corals, starfish, or shelled creatures." (Golden Guide to Scuba Diving, 1968) :D

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Herman
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Re: Air Consumption - Double Hose

Sun Jan 19, 2020 8:54 pm

You def can crank up the venturi so that it blows by but most don't crank them up that high and even then, if you are careful you can get away with it. Without the DSV, I don't recommend doing so unless you just want to experiment, the reg can get unstable if you go too far. Properly set up a DH with a HPR can hold it's own with most any modern reg. My Argonaut was tested on the LDS's machine and it beat the pants off top of the line Scubapro and Atomic regs. A Poseidon was the only reg that beat it. The SP and Atomic did outperform the AK at very high flow rates, way above what any person could breath. If you shed the huge BC, I use a 15 lb wing or often none at all and get your weights right your air will improve a lot.
Herman

scrane
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First Name: William

Re: Air Consumption - Double Hose

Mon Jan 20, 2020 8:49 am

Thanks, gentlemen.

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couv
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Re: Air Consumption - Double Hose

Mon Jan 20, 2020 1:14 pm

I've been diving DH for about 6 years now. At first my air consumption with a DH was greater than with SH; but now (due to issues already mentioned) I think my SAC rate is the same.
A sincere THANK YOU to all at VDH who make this wonderful resource available and to all the thoughtful contributors.

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Ron
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Re: Air Consumption - Double Hose

Mon Feb 03, 2020 5:29 pm

The only time I think this rule of thumb about air consumption being the same doesn't hold true is with something venturi-less like a DA Navy or Broxton. Those will crush your will to live a little bit. Anything with a venturi assist is about on par with a regular modern diving regulator though.
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