Fathom SPG question

[mrki]

The 10+ hours of available oxygen in a 3L cylinder exceeds the recommended scrubber duration of even the large 8.8 lb scrubber so not much use in monitoring oxygen reserves during the dive.

Come to think of it, even increased oxygen consumption doesn't matter as any increase in oxygen consumption automatically consumes the scrubber as well. As long as you're not filling lift bags with oxygen.

We're only talking about oxygen right? Diluent tank has an SPG?

[rddvet]

Come to think of it, even increased oxygen consumption doesn't matter as any increase in oxygen consumption automatically consumes the scrubber as well. As long as you're not filling lift bags with oxygen.

We're only talking about oxygen right? Diluent tank has an SPG?

Diluent is all off board. The second 3l tank is suit gas. Most of us run spgs on our bailout/diluent. Floridabob says he doesn?t. I don?t think I?d be bold enough to skip those spgs but honestly his idea isn?t that crazy. Except for predive I pretty much rarely look at my dilout spgs. And those are the bastards that always leak. I don?t know if I ever had to bailout if I?d be comfortable not seeing my gas level. But then again I should be focusing on getting out and have enough bailout.

[jason]

Diluent is all off board. The second 3l tank is suit gas.

And how is the wing plumbed in?

[rddvet]

Wing comes from same bottle as suit gas. Not much of an issue in cave diving though theres some ow divers that prefer separate suit and wing sources. In that case then a separate bottle for suit inflation on the backplate may be wise. I dont do the type of ow diving that would require that concern so I dont have much of an opinion on their point.


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[jason]

Wing comes from same bottle as suit gas. Not much of an issue in cave diving though theres some ow divers that prefer separate suit and wing sources. In that case then a separate bottle for suit inflation on the backplate may be wise. I dont do the type of ow diving that would require that concern so I dont have much of an opinion on their point.


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Thanks!

[JahJahwarrior]

I swapped the SPG on a hose for button gauges on my o2ptima in the parking lot after my last certification dive.

I think the risk of a button gauge failure is low and I do think there is value in being able to tell how full a bottle is, more or less, so my dilout and bailout get button gauges.

It would be a little difficult to run out of suit and wing gas when starting with a cave filled LP27, and many cave profiles would not require descending further to exit in an emergency...but a wing could be filled by mouth off the loop, and you could use an adaptor for qc6 to suit inflator or just throw a spare inflator hose on a bailout bottle.

Are you guys writing down every tank pressure, o2 and co on a checklist pre-dive? Do you ever begin a dive with less than full tanks? What's your limit on starting o2 cuft vs. scrubber capacity vs. planned dive length?

[JBaldwin]

Suit and wing inflation bottle is (left on board cylinder)with the valves upright the hoses for the wing and suit route just like a dir configuration in doubles.the unit has a feed line off the mav as well as the bov comes off of a pass trough in the top of the diluent mav which is fed by off board diluent via a qc6.so what every your driving the unit with is also What’s feeding the bov. One of the many things I love about the fathom.the unit is super clean and amazing Charlie really did a great job with it. If you every want to see one in person I would gladly show you mine and I’m sure anyone who has one wouldn’t mind showing you there’s.theres also a website now https://www.fathomdive.com/

[rddvet]

I swapped the SPG on a hose for button gauges on my o2ptima in the parking lot after my last certification dive.

I think the risk of a button gauge failure is low and I do think there is value in being able to tell how full a bottle is, more or less, so my dilout and bailout get button gauges.

It would be a little difficult to run out of suit and wing gas when starting with a cave filled LP27, and many cave profiles would not require descending further to exit in an emergency...but a wing could be filled by mouth off the loop, and you could use an adaptor for qc6 to suit inflator or just throw a spare inflator hose on a bailout bottle.

Are you guys writing down every tank pressure, o2 and co on a checklist pre-dive? Do you ever begin a dive with less than full tanks? What's your limit on starting o2 cuft vs. scrubber capacity vs. planned dive length?

I have a cheater in a pocket just in case. Natalie Gibb at under the jungle sells some super short inflator hose. Like 2-3 inches. I put it on a qc6 just to be safe but doubt it will ever get used.
Prior to every dive I know all starting pressures. I also record end pressures after dives so that I can then calculate average consumptions in different caves. I do repetitive dives on a single oxygen wnd suit bottle fill. I?ve never come up with a rock bottom number. I just do a quick mental exercise to see if I have enough gas based on average consumption and the dive I?m about to do. I?ve never gotten to the point that I would be even close to pushing it.

I still have less than 100 hours on the unit so Im still finding my gas consumptioms decreasing. So the calculations are interesting to watch change as my comfort grows.


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[bent]

What's the reasoning for not wanting to use the other onboard tank for diluent? Is this a unique fathom-thing?

Edit: The new fathom website is looking pretty good.

[rddvet]

What's the reasoning for not wanting to use the other onboard tank for diluent? Is this a unique fathom-thing?

Edit: The new fathom website is looking pretty good.

I don’t know the exact original reasons. For me it’s not having to add an additional inflation bottle for trimix and not having my bov plumbed into a tiny 3L bottle.