Electronic vs manual CCR

Status
Not open for further replies.
Dave Sutton said:
Absolutely right...and well said.

The old US Navy Mark-15 procedures were to turn the rig on before donning and let it come to 0.7 set point ( standard then). The manual said basically " on descent you should not be surprised to see your primary display high PP02 alarm light illuminate. This is normal, and it will extinguish after some period on the bottom as excess oxygen is metabolized". Similarly the manual told divers to ignore low PP02 primary display light indications on ascent.

Body is happy between about 0.15 and about 2.0... All of the rest is really just decompression and narcosis.
Click to expand...

Dave Sutton said:
Reading thru, it appears to be "B", use of purely inert diluent to avoid PPO2 increase upon descent. He's made a few allusions to this if you read carefully.

Noting as a data point that when we did the deep work with CCR's for saturation bell lockout (umbilical fed) we had pure He as diluent. This was in the 150-300 meter depth range.
Click to expand...

greet rc
 
anarchista said:
Manual is an Italian oxygen CCR and electronic to everyone who has measurement oxygen partial preasure?
Suggest specific models to be compared.
Click to expand...

:-) Now you are being delibrately difficult- well you know that the M and E refer to Manual and Electric PPO2 control in CCR in normal parlance.
 
Even if we did find out which type of unit was "safer" would it make any difference?
What would the manufacturers do with this knowledge

Would everyone scramble to change to that type of unit

I do not think much would change. It's a personal choice that we all make

Paul

Sent from my GT-N7100 using Tapatalk 2
 
Last edited:
paul t said:
Even if we did find out which type of unit was "safer" would it make any difference?
What would the manufacturers do with this knowledge

Would everyone scramble to change to that type of unit

I do not think much would change. It's a personal choice that we all make

Paul

Sent from my GT-N7100 using Tapatalk 2
Click to expand...



I have developed the opinion that we should all learn to dive on MCCR before switching to ECCR (if the need is felt)


I know Leon used to get his Meg students to run the Megs manually for a while ofter training. It educates you on how the machine works and quickly highlights critical points in dives where you rely need to be on your game.

ECCR is switch on, breath in breath out switch off when dive over. When its working correctly it teaches you nothing.

ATB

Mark
 
I have to agree with Mark. I know that going to a mccr has made me both a safer diver and a more aware diver. Eccr was making it too easy for me to get complacent.
 
DSix36 said:
I have to agree with Mark. I know that going to a mccr has made me both a safer diver and a more aware diver. Eccr was making it too easy for me to get complacent.
Click to expand...

If you have a ECCR with a HUD, how is it even possible to controll PO2 more on a MCCR?

You have it straight in front of your eyes all the time. It would be comparable to looking at the handset during the whole dive. If the HUD shows a a fault you will notice it right away.
 
Last edited:
erikradstrom said:
You have it straight in front of your eyes all the time. It would be comparable to looking at the handset during the whole dive. If the HUD shows a a fault you will notice it right away.
Click to expand...
High ppO2 limited field of vision, tunnel vision. There is a known physiological response. Additional come: ppN2, ppCO2, ppHe, cold, darkness and reload tasks.
Eccr gives a lower level of control needed

greet rc
 
erikradstrom said:
If you have a ECCR with a HUD, how is it even possible to controll PO2 more on a MCCR?

You have it straight in front of your eyes all the time. It would be comparable to looking at the handset during the whole dive. If the HUD shows a a fault you will notice it right away.
Click to expand...

:) You'd think so wouldn't you.... I've seen plenty of CCR divers (on either type) ignore displays and HUDs, why- because "seeing" is one thing but actually reading is another!

(Years ago when I learnt to drive the instructor would occasionally cover the mirror and ask what colour the car behind was.... despite knowing he'd do this and having often checked the mirror I didn't always know the colour)

Nothing to do with High PPO2- people are inheritly lazy, long before they are impared by their loop contents they will happily ignore the information infront of their nose.


"Control" is not the priority either- the diver is there to observe the rebreather, on ECCR you are 100% observation only, on MCCR its probably 80% observation, 20% intervention.... the 20% makes a difference in the way you observe though.
 
anarchista said:
High ppO2 limited field of vision, tunnel vision. There is a known physiological response. Additional come: ppN2, ppCO2, ppHe, cold, darkness and reload tasks.
Eccr gives a lower level of control needed

greet rc
Click to expand...

If you miss the warnings so far you are probably blind from the beginning. You will not suffer from tunnel vision at PO2 1.5 and then you have had several chances to do something. If you miss that on a HUD you will do it on a handcontrol on a MCCR as well.

A ECCR doesn NOT give a lower level of control, you need to check PO2 just as much as on a ECCR as a MCCR. If you think like that you should stay on land.
 
erikradstrom said:
You have it straight in front of your eyes all the time. It would be comparable to looking at the handset during the whole dive. If the HUD shows a a fault you will notice it right away.
Click to expand...



You don't, actually. You look "past it" most of the time.

First, these devices are not HUD devices, they are Peripheral Field Displays. You normally look "past" or "around" them and need to consciously "code shift" your observational point to use them.

Second, any "constant stimulus device" in the visual field will very quickly be ignored by your brain.

The fallacy is that somehow "you cannot ignore a HUD". Nothing could be further from the truth.


Dave


.
 
erikradstrom said:
If you have a ECCR with a HUD, how is it even possible to controll PO2 more on a MCCR?

You have it straight in front of your eyes all the time. It would be comparable to looking at the handset during the whole dive. If the HUD shows a a fault you will notice it right away.
Click to expand...

As every one has said. You don't see the HUD all the time you have to consciously look at it.

I have had my HUD fall off and i didn't notice till i mentally stopped to check my PP02

Good news is a green flashing HUD that fades into insignificance becomes IN Ya FACE when it starts flashing red.


The big thing MCCR teaches you is, You alter depth you check PP02, your about to get involved in doing something, (bagging a lobster lifting some spidge) you check your PP02. It makes you very aware of how the unit will react to what your doing.

The other thing it teaches you is how often and when you need more 02. You begin to gain an instinct for when you need to inject. I can honestly say once attuned to my MCCR I injected out of habit more than consciously needing to check my PP02 and adjust it.

Out of habit on the surface you immediately 02 flush as you become almost blind to your HUD and hand sets and your often working hard to get back on the boat. Surface? 02 flush, about to climb the ladder 02 flush

Same with getting in the water

Stand up? 02 flush

Walk to back of boat and prepare to jump in? 02 flush

It removes danger from critical times where ECCR divers have died as they expected the machine to take care of everything, and it didn't.


You dive a MCCR nd it starts to demand more injections than your used too and it makes you stop and think why is this happening.

You go 15mins without a reduction in 02 readings you think, hang on thats not right, whats going on?

On ECCR you just get 1.3 1.3 1.3 glossing over all the calibration issues and unit performance issues until the day you don't. And thats the day your computer induced apathy could kill you.


I was happily finning allong at 12m when my aftermarket HUD flashed red on my old Inspo Classic.

That was the first i knew that BOTH handsets had shut down.

I had been running 1.3 so all the time it took to decay from 1.3 down to 0.9 for my HUD to go red, I hadent noticed.

Its often crossed my mind that 11/11/2005 was the day i should have joined the list of statistics. All but for my decision (against general advice for the CCR comunity and in contravention of APD policy on their units) to fit a HUD.

ATB

Mark
 
Mark Chase said:
Good news is a green flashing HUD that fades into insignificance becomes IN Ya FACE when it starts flashing red.
Click to expand...
Would it be a good idea to flash red at random times, but somehow indicate that the flash was only to keep you on your toes, not an actual loop issue?
 
Status
Not open for further replies.
Back
Top