Integrated Power Inflators Are A Terrible Idea!

[John C. Ratliff]

How do the specs of breathing on the AIR2 compare to modern second stages? In the ballpark? Markedly inferior?

The Scubapro specs for the A.I.R. II on the surface show a breaking pressure of about 1.4 inches of water. At 100 feet its 2.4 inches of water. This, I think, is much poorer that today's regulators, which are usually under 1 inch of water on the surface and don't go up at depth. However, in the 1980s I got my Scubapro Manual for Scubapro Regulators, and the Mark V First Stage with a 109 second stage showed inhalation on the surface at less than 1 inch of water, but at 100 feet going up to about 2.5 inches of water. So at the time the A.I.R. II was about the same as the 109 second stage. However, the Pilot and A.I.R. I regulators stayed at less than one inch of water regardless of depth. The Scubapro A.I.R. I and Pilot regulators actually broke at under one inch, and then became virtually effortless at depth. Here's some more information from the U.S. Navy EDU in the 1980s:

https://apps.dtic.mil/sti/pdfs/ADA186590.pdf

mark-ii-25.html

I don't know about today's regulators, as Scubapro and maybe other manufacturers stopped publishing this data in their catalogs and manuals. Aqualung has a breathing curve for its Titan LX which shows a breaking at just over 5 millibars (x 0.402 to get inches of water) for 2005. So I don't think the regulators have progress a whole lot, except for those with pilot valves.

I measured my own regulator collection some years ago using a water monometer.

SeaRat

PS, I just added two more pages from my notes, one of which was exhalation resistance and the other explaining the study.

 

[John C. Ratliff]

I doubt most regulators have much more than 6 moving parts. I know my Sherwood's have 5 (if I'm counting right.)

Well, yes, until you count the octopus, inflator, SPG, and/or second regulator. Every addition is an additional fault. When I started diving, my first single hose was a Healthways Scuba Star, which had a spring in the first stage, and a piston (with an O-ring). The second stage was a tilt valve with a tilt valve, and diaphragm (three moving parts, if the spring is included). So that was five moving parts. Several years later, no malfunctions. My second single hose regulator was an AFM Voit 40 Fathom (Voit's copy of the Calypso). It had a diaphragm first stage, with I think 5 moving parts and a second stage with 4 moving parts, for a total of 9 moving parts. Hannes Keller took that regulator to 1,000 feet in the 1960s (the USD Calypso version) without problems with the regulator (but with significant problems with gas handling). The point about how many moving parts are involved involves how many points of potential failure you are introducing to the system, along with all those O-rings (the Mistral had only one O-ring, which was not critical to its operation).

SeaRat

 

[John C. Ratliff]

I found the "Instruction Supplement SCUBAPRO A.I.R. II" from Scubapro in my files. It is a PDF, and gives not only the philosophy of the A.I.R. II, but also a templet for instructors to teach about the A.I.R. II. This will give Scubapro's Design philosophy and specifics on training for the A.I.R. II.

SeaRat

PS, It took me three tries to get this scanned.

PS-2, I also found the current version of this document about the Scubapro AIR2, 5th Generation. But interestingly, it is not as thorough as the original one below.

https://ww2.scubapro.com/en-GB/HKG/regulators/products/air2-manuals.aspx