Question FFM risks?

[Bigbella]

I keep seeing this "increased air consumption" being thrown around when talking about "FFM Cons". Where does the data come to support this?

Irritatingly enough, the answer to whether there is "increased air consumption," is both yes and no.

Not all full face masks are alike in design or function.

While the ScubaPro mask, mentioned in the previous thread, is a nice FFM, it is of a simple "on demand" design (that is, only delivering air upon inhalation and generally involving little to no more air consumption than standard scuba), with a conventional regulator stem fixed to the mask interior by cable ties, with or without a mouthpiece, just like the old Cyklon / Turbulent Tauchtechnik models of decades past, rather than, say, a positive pressure FFM, such as the Poseidon Atmosphere with an integral "Jetstream PP" second stage, which incrementally free-flows into the mask's interior, whether one is actively breathing or not, both for anti-fogging; for venting and the minimization of any potential CO2 buildup; and to further protect a diver from suspect waters, by isolating his or her face from the outside.

Positive pressure masks consume more air, by their very design -- though that is not to be confused with novice FFM use of either form, who will invariably tend to consume more air out of sheer unfamiliarity, until they grow more comfortable with the masks . . .

 

[BlueTrin]

Here is the quote from the website, it’s very clear:

Notice: As of 29 April 2022, No one is permitted to use any Full Face Mask while on tours with our company for SCUBA Diving OR Snorkeling. * Sorry, zero exceptions to this policy.

When I wrote and asked for the reasons they said there had been too many fatalities. So I decided to post here to see if anyone had data on fatalities associated with FFMs and scuba. I can avoid the dive shop, that’s not a problem.

I’m just trying to make sure there isn’t some hidden danger with FFMs that I should be aware of before my next dive trip.

Thanks for the input so far. I appreciate it.

Key Largo Scuba Diving & Snorkeling - Sail Fish Scuba FL Keys Dive Shop

Best dive shop in Key Largo, Sail Fish Scuba offers PADI 5-Star dive instruction, guided scuba dive trips, snorkeling and kayaking tours in the Florida Keys

sailfishscuba.com

 

[Bigbella]

Key Largo Scuba Diving & Snorkeling - Sail Fish Scuba FL Keys Dive Shop

Best dive shop in Key Largo, Sail Fish Scuba offers PADI 5-Star dive instruction, guided scuba dive trips, snorkeling and kayaking tours in the Florida Keys

sailfishscuba.com

Again, there's that unstated though weird conflation, in the language, between the use a scuba full-face mask, which would be completely useless for any snorkeling activity, and what they can be only referring to as those domed Kevorkian death snorkels, of which they bear no relation . . .

 

[SpaceWarMachine]

There is no data to support this, because it is not true. I dive a Scubapro FFM on SCUBA 2 to 3 times a week at work and there is no difference. I spend more time in the water than anyone else in my company on a tank. Now if you are talking about a KMB Band mask running on surface supply and constant flow on top of demand then yeah, of course, but nobody here is talking about that. Most all non commercial models do not have that capability anyway.

Full Face Masks do not use more air than diving a regulator alone. As a matter of fact I am more relaxed and do not have to spend effort gripping the mouthpiece, so I may even use less air in the FFM. YMMV.

EXACTLY, these guys have ZERO idea what they are talking about. For whatever reason, they just have some need to spread false info.

 

[Bigbella]

EXACTLY, these guys have ZERO idea what they are talking about. For whatever reason, they just have some need to spread false info.

You're out of your depth.

Of the two masks below, the Poseidon Atmosphere, on the right, demonstrably consumes more air by its very design, which slightly free-flows to flush residual CO2 and why I will often carry a manifold on longer dives to switch-out tanks; while the other model, fitted with the older Cyklon second stage (which hasn't really changed in fifty years), is a conventional "on-demand" design, with a mouthpiece, which negates any need for free-flow or any CO2 worries, and consumes no more air than any other open circuit diving. It can also be worn under a hood, unlike the Atmosphere, which would cause unpleasant buoyancy issues, due to its air-flow characteristics.

I have used and serviced both models for decades; and the question of increased air consumption depends entirely upon the mask design -- so, yes and no.

From The Encyclopedia and Guide To Diving with a Full-Face Mask (2012):

"Most regulators in full face masks are demand [designs], meaning [that] the regulator delivers breathing gas, at or above ambient pressure, only when the diver begins to inhale and then stops [upon exhalation]. Some full face masks are "free-flow" which means that the regulator is constantly delivering breathing gas regardless of the diver's [respiration]. This is not efficient for scuba as it requires a large breathing supply which is not realistic with the utilization of a scuba tank. With surface supplied diving, using low pressure compressors as a gas supply, free-flow masks are widely used in commercial diving.

"Positive pressure masks may consume more breathing gas than [their alternatives] and this can be a disadvantage . . ."