High SAC with FFM

[Icarusflies]

Hello All;

Yesterday I went for a dive with my father who was diving for the second time his FFM OTS matis. His consumption was very high (41 l / ) he drained a 16 liters tank (130 cuf ) in 40 min at an average depth of less than 30 feet.

The reg he is using is the same that he has been using for a long time, a Dive Rite.

He is wearing a hood so it might be that the seal of the FFM is not working properly and somehow this is causing some kind of a gas escape...

Any sugestion or comment of what this dramatic increase in SAC clould be?

Thanks;

Steve

 

[fisherdvm]

Claustrophobia and anxiety?

 

[JohnnyH]

I dive the Ocean Reef Neptune Space quite regularly for work, along with the AGA Divator, and it's a fact of life that FFM go through air much more rapidly than a regular mask / reg.

I attribute this to two reasons:

- Frequent free-flow around mask skirt that changes with orientation in the water column. This happens regardless of hood or no hood and is more prevalent at shallower depths

- Since a FFM contains a fairly large volume, as depth is reduced and the gas contained within the mask expands, some of this air is vented. If fairly shallow and the profile contains many minor ups and downs, the mask 'pumps' air out.

Of course, diving a FFM mask for the first few dives will also consume more gas as the diver acclimates to the new experience...

Best,
John

 

[Icarusflies]

Thank you guys for the feed back.

I am aware that FFM's increase the SAC but 80% more like in the case of my father.....I am just asking?

Steve

 

[Gary D.]

They will increase it a but but once he relaxes there won't be much of a difference. I have been diving ff for over 40 years and have a better rate than most I dive with.

Gary D.