Doing AN/DP with FFM, Realistic?
- Thread starter cruisekingkris
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cruisekingkris
Contributor
OK, Switch blocks won't be a part of my kit. I feel they shouldn't be used for different gasses. Just my opinion.
As for the Course... Half mask it is.
@ChuckP oddly enough this is all leading to me taking Johns class early next year. So if you could send a quick review of his class when you finish (through DM if you don't want it to be public) that would be great!!!!!
Part 2 of the question, whats you ffm setup look like when running doubles? what posts get what and hose length used for ffm and backup?
As for the Course... Half mask it is.
@ChuckP oddly enough this is all leading to me taking Johns class early next year. So if you could send a quick review of his class when you finish (through DM if you don't want it to be public) that would be great!!!!!
Part 2 of the question, whats you ffm setup look like when running doubles? what posts get what and hose length used for ffm and backup?
tmassey
Contributor
I will - I was going to do some kind of write up as I’ve never dove in doubles or took ITT. I’ve dove two days with him and been in the shop a few days, he’s very open about things, very helpful as are the guys working with him - and my class hasn’t even begun
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the way my switch block is plumbed has each input with a QC6 on it. It's intended for IWR use, so it's a little different, but the thinking would be that you would only have the intended breathing gas plugged in. I.e. backgas is plugged in, start ascent and get to 70ft, then you plug in the EAN50 bottle, switch, unplug backgas. Deco deco deco, get to 20ft, plug in 100%, switch, unplug EAN50. For air breaks, plug in, switch, breathe for x-minutes, switch back, unplug.
Would never plug in a nonbreathable gas, similar to plugging in CCR's. Use of switch block is to prevent any lapse in gas being plugged in since QD's can be a bit of a PITA, or you may choose to leave backgas hardlined if you're on doubles.
The Sartek valve is light enough to mount directly to the FFM so it is at your face and has a red ring on the "aux" side for your buddy to ID. You'd have the RSV mounted to the second stage, backgas hardlined, then a hose coming around with a QD on it to plug in since plugging into your face would likely be awkward and if using QC6's would be very heavy.
Again, I don't dive like that, so I would be very hesitant to teach it, but someone out there is likely doing it so there has to be an answer. I think the complexity of the switch block is a worthwhile compromise against the risk of a QD not engaging while you have no breathing gas.
Would never plug in a nonbreathable gas, similar to plugging in CCR's. Use of switch block is to prevent any lapse in gas being plugged in since QD's can be a bit of a PITA, or you may choose to leave backgas hardlined if you're on doubles.
The Sartek valve is light enough to mount directly to the FFM so it is at your face and has a red ring on the "aux" side for your buddy to ID. You'd have the RSV mounted to the second stage, backgas hardlined, then a hose coming around with a QD on it to plug in since plugging into your face would likely be awkward and if using QC6's would be very heavy.
Again, I don't dive like that, so I would be very hesitant to teach it, but someone out there is likely doing it so there has to be an answer. I think the complexity of the switch block is a worthwhile compromise against the risk of a QD not engaging while you have no breathing gas.
Well, kinda depends on the the profile your running. I deco on back gas often if I'm in no particular hurry.
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whole point of AN/DP is accelerated deco.....
Just do it in a normal setup and when you've got some experience actually doing those dives, then figure out a way to work your FFM into the equation.
If you decide to do doubles with an FFM once you're certified, I'd recommend connecting your FFM to your short hose so that your long hose is always donateable. The Drager Panorama excels at this type of setup with a P-ported Apeks second stage, and most guys I know that FFM their rebreathers have this setup, albeit with the reg into one of the side ports. Close the dsv and breathe through your nose and you're on OC. Note it has equalizer window wipers instead of a nasal block. A similar setup may not be possible with a mask that uses a nasal block.
Gas blocks are s-k-e-t-c-h-y. Using it for IWR is a very controlled process, with support divers in controlled conditions, much more so than a normal deco dive. Using it with one gas like the quote Ken posted is the right way to use them. CCR use is a whole other animal and irrelevant to the discussion, but typically that gas is never used in the first place. It's bailout or dil, the likelihood of using both is hopefully fairly small past initial descent.
Gas blocks just don't give me a warm fuzzy feeling for open circuit gas switching. Unplugging QD's and leaving no breathable gas connected while you fumble to plug in is schoolyard stupid. I think the best of a bad situation is like tbone1004 described using the Sartek RSV. I use one for my IWR setup, it's really the only thing I would consider in an actual switching situation. Something like the RSV on the left shoulder, one in from backgas, one with a QC6 female, one out to your FFM. QC6 male on your deco bottles. Do all the gas switch procedures as you're taught, depress the tip of the QC6 instead of purging the second stage, plug in and switch. When you go to switch again, you go to backgas, do all your switch procedures, then switch to your new deco gas. You ALWAYS have breathable gas plugged in, and in theory you should never be switching to the wrong gas. Honestly I'd probably go as far as to dump the previous stage to noseclipped or a leash before the new gas just to be extra doubly 100% sure there's no way to plug in the wrong QC.
If you decide to do doubles with an FFM once you're certified, I'd recommend connecting your FFM to your short hose so that your long hose is always donateable. The Drager Panorama excels at this type of setup with a P-ported Apeks second stage, and most guys I know that FFM their rebreathers have this setup, albeit with the reg into one of the side ports. Close the dsv and breathe through your nose and you're on OC. Note it has equalizer window wipers instead of a nasal block. A similar setup may not be possible with a mask that uses a nasal block.
Gas blocks are s-k-e-t-c-h-y. Using it for IWR is a very controlled process, with support divers in controlled conditions, much more so than a normal deco dive. Using it with one gas like the quote Ken posted is the right way to use them. CCR use is a whole other animal and irrelevant to the discussion, but typically that gas is never used in the first place. It's bailout or dil, the likelihood of using both is hopefully fairly small past initial descent.
Gas blocks just don't give me a warm fuzzy feeling for open circuit gas switching. Unplugging QD's and leaving no breathable gas connected while you fumble to plug in is schoolyard stupid. I think the best of a bad situation is like tbone1004 described using the Sartek RSV. I use one for my IWR setup, it's really the only thing I would consider in an actual switching situation. Something like the RSV on the left shoulder, one in from backgas, one with a QC6 female, one out to your FFM. QC6 male on your deco bottles. Do all the gas switch procedures as you're taught, depress the tip of the QC6 instead of purging the second stage, plug in and switch. When you go to switch again, you go to backgas, do all your switch procedures, then switch to your new deco gas. You ALWAYS have breathable gas plugged in, and in theory you should never be switching to the wrong gas. Honestly I'd probably go as far as to dump the previous stage to noseclipped or a leash before the new gas just to be extra doubly 100% sure there's no way to plug in the wrong QC.
Addicted2H2O
Contributor
Looks like Oceanreef now has a dual tank valve for the same purpose. Looks to be very similar in operation to the Sartek at nearly half the price, which for Oceanreef is saying something because they're gear is still pretty spendy. Downside is it's only compatible with up to EAN40.
DUAL TANK VALVE - OCEAN REEF Diving
Edit: It should also be noted that because I'm not yet a tech diver and still somewhat new to scuba (relatively speaking) I wasn't aware something like this existed when I suggested using QD fittings to switch over. Although I've never had any issues reconnecting a pressurized line either in or out of the water, I do see the merit of a RSV and it's definitely a better option if you're using two gases. However if you're using three or more then you'd have to figure something else out. Unless of course you connect the RSV's in succession, which then seems like it might get a bit dicey. Still though the RSV has certainly made my list of necessities when I decide to go to AN/DP.
DUAL TANK VALVE - OCEAN REEF Diving
Edit: It should also be noted that because I'm not yet a tech diver and still somewhat new to scuba (relatively speaking) I wasn't aware something like this existed when I suggested using QD fittings to switch over. Although I've never had any issues reconnecting a pressurized line either in or out of the water, I do see the merit of a RSV and it's definitely a better option if you're using two gases. However if you're using three or more then you'd have to figure something else out. Unless of course you connect the RSV's in succession, which then seems like it might get a bit dicey. Still though the RSV has certainly made my list of necessities when I decide to go to AN/DP.
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