Technique for Cleaning the Loop....

schford

OK then its official Im crap at it...

Hanging around at 6 metres with about 7 or 8 mins of deco to do bored so think I know lets practice that technique we were all talking about last week...

So its right then, check PPo2 1.25ish ok then here we go.....empty loop through my nose keep going till when I try to breath in nothing comes, ok pretty good I think - lets add some O2 - a good squirt in, breath it around and umm hardly any change ok I think no probs this takes 4 or 5 gos...

So repeat and rinse I mean add O2 ....Well 5 goes later and I get 1.43, 1.43 and 1.45 humpth

Ok then wait a few mins and try again - but I just could not get it up above 1.45 is this one of those skills that when it clicks you think pah so thats how you do it!

I just hate not doing things right first time....

Stuart

Decodiver

Hi Stuart,

You need to get as much of the dead space empty as possible, cross your arms over the lungs and assist the exhalations, also remember that you can only select 98% O2 on the Meg, so say you were using in reality 100% this will have a marginal effect on your readings, ie the real PPO2 in your loop will be higher than that shown on your handset.

Another tip, do the flushes when you are vertical as this will assist in evacuating through your nose and mouth, oh and keep trying...........

Cheers,

Dave

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caveseeker7

If you crush the bags, they'll both be pretty empty. Since your O2 add is on the inhalation side you'll be getting it immediately, without moving gas out of the scrubber. Your breath will also include left over gas from the hose. Exhale you fill the lung, still not moving (much) gas around the loop. Squeeze exhale bag again to move it to inhalation side, inhale and dump (or add O2, take a full breath into loop and move the gas that way - watch bouyancy).

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onetime

I've got it a little easier with the KISS as I simply switch the DSV to OC for exhales and switch back to closed for the inhales while adding the O2 manually. This lets me clear the loop pretty completely relatively quickly.

I know you're asking a more unit specific procedure but figured I'd throw it out there for idle chatter.

jradomski

Work at it you will get it.. On the MEG you have to move the gas around alot more than someone with an inspiration because your o2 add is on the inhale counterlung.. hold the o2 button to make sure it gets blown around the loop..with the crushed lungs it should still be forced out the over pressure valve.. DOn't play with pressing/releasing the o2 add.. just hold it in... The fist flush of yourlungs is important.. after you inhale as much of the loop as possible, exhale til there is noting more that can be done.. now take the biggest inhale that you can (of oxygen) and blow this out to the water..At this point you should still be holding the button in take a few good breaths and blow them arounfd the loop, take a deep breath and vent it.. by now you should be close..if you just do a suck, blow 4 times it wount work becuase of where the o2 is added..

The mak you will probably show is about a 1.56 assuming you calibrated correctly and your sensors are ok..

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Drmike

It wasnt until I started doing O2 flushes at 6m that I realised just how poor my calibration was on my YBOD. I would double check your calibration method and sensors if I was you. If you only get 1.45 it might be a good idea to try dropping down a meter and see if it rises to 1.55, if not it maybe time to bin the sensors. Also if you suspect the calibration is out you can always sit just shy of 3m with setpoint 1.3 and see what happens.

Sometimes Im just having a bad day and it takes forever to get it up near 100%.

Drmike

Even eaiser, on my MK15.5 when I reach 6m I can plug my bail O2 into the ADV. Then I empty the loop and exhale through my nose on each breath firing O2 thru the ADV on enhale until the loop ppo2 is 1.55 ish. The ADV also means I dont have to keep manually adding O2 to keep the loop volume during deco and that helps a little with bouyancy in the shallows.

schford

Thank you all - some brill pieces of advice, so its off to Wraysbury I go to play with this skill wednesday!

Stuart

Pelagian

Hey Stu

Just something that Eric and I do on our megs to purge.

We noticed moving from the Inspo to the Meg it was harder to do a full o2 purge at 6m because of the loop reversal.

This is what we came up with.

If your in a horizontal position roll to your right and just slightly head down.

This will raise the the dry suit dump valve on your exhalation lung into a high position on your loop.

Loosen the valve to minimum resistance and press it while flushing the loop with 02, keeping the mouthpiece sealed. This will flush the loop in only a few seconds and bring your setpoint right up to 1.6 at 6m.

The cool thing about this is it allows you to maintain a horizontal hover and/or swimming position while purging.

This saved a lot of time, frustration and O2 from the mouth purge method we used before. It does require a second hand but for the few seconds it takes it's, and the fact it doesn't interupt your swimming it's worth it.

Cheers

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