What is the primary objective of pre-breathing a manual CCR?

[lostsheep]

I concider the study questionable because despite the data, somehow people interpret it as prebreaths are unnessasary. So clearly its poorly written. See part of science is defending your results and presenting them in such a way that even the dumbest amongst will agree with the findings and reccomendations. In this case the author failed to convince a lot of people.

Seriously? You’re calling out clarity issues whilst your own posts are riddled with grammatical and spelling errors?

Cool story bro, last word is yours before I get banned.

Edited for punctuation

 

[bletso]

So, there's a benefit for needle valves vs orifices. Me use needle.

In some circumstances perhaps. My design and orifice sizing is based on max depth of 100 MSW with a fixed IP and the flow rate which matches my normal VO2 requirements. In normal usage I may not need to add O2 but once in an hour dive. If I add O2 it's because I have exerted myself for some reason. My PO2 is monitored frequently, no electronics except the for O2 sensors. Purely a thumb/brain system.

 

[fullytek]

Seriously? You’re calling out clarity issues whilst your own posts are riddled with grammatical and spelling errors?

Cool story bro, last word is yours before I get banned.

Edited for punctuation

Clearly

 

[lostsheep]

Clearly

Alright, I know I said last word but I have to acknowledge the preceding post as grade A **** talking and actually put a smile on my face , well played.

 

[crofrog]

I concider the study questionable because despite the data, somehow people interpret it as prebreaths are unnessasary. So clearly its poorly written. See part of science is defending your results and presenting them in such a way that even the dumbest amongst will agree with the findings and reccomendations. In this case the author failed to convince a lot of people.

Your critique of the study is baseless. Claiming it’s “questionable” just because some misinterpreted it as saying prebreaths are unnecessary is lazy thinking. A study’s job isn’t to spoon-feed clarity to everyone it’s to present solid data and methods, which you haven’t even bothered to challenge.

 

[fullytek]

Your critique of the study is baseless. Claiming it’s “questionable” just because some misinterpreted it as saying prebreaths are unnecessary is lazy thinking. A study’s job isn’t to spoon-feed clarity to everyone it’s to present solid data and methods, which you haven’t even bothered to challenge.

Than explain to me how half of the respondents to this thread have referenced the verry study to justify skipping the procedure they were all taught.

And for the reccord using the term lazy thinking is just lazy arguing.

 

[crofrog]

And for the reccord using the term lazy thinking is just lazy arguing.

So you are capable of understanding the issue with your argument. I wasn’t sure there for a while.

 

[SeafoamGreenMonster]

Than explain to me how half of the respondents to this thread have referenced the verry study to justify skipping the procedure they were all taught.

And for the reccord using the term lazy thinking is just lazy arguing.

I'd argue the problem is lazy instructors who don't keep up with developments. Part of my CCR class at the start of the year was this paper - pre-breathing isn't for scrubber integrity; it's for confirming everything else works. Given the paper is 11 years old, there's really no excuse for a tech instructor not being familiar with the research. Blaming the source for people not understanding the material is asinine.

Edit: also, if you want people to take your arguments seriously for a technical subject, spelling my guy.

 

[Snusmumrik]

In some circumstances perhaps. My design and orifice sizing is based on max depth of 100 MSW with a fixed IP and the flow rate which matches my normal VO2 requirements. In normal usage I may not need to add O2 but once in an hour dive. If I add O2 it's because I have exerted myself for some reason. My PO2 is monitored frequently, no electronics except the for O2 sensors. Purely a thumb/brain system.

Ok, mea culpa, let's clarify.
My design and needle valve setting is based on CMF to max depth of 60 MFW
with a fixed IP of 12 bar and the flow rate which matches my normal O2 requirements.
I don't touch needle valve during dive.
My PO2 is also monitored frequently, 2 computers look for O2 sensors. Purely a thumb/brain system - i.e KISS.
In these conditions, IMHO, adjustable needle valve prove better than orifice.
1. To clog needle valve needs much more debris than to clog orifice.
2. Simple flowmeter check shows you all is ok/not ok.
3. Needle valve can be easily de-clogged using screw/spanner and flowmeter, this delays but not ruins dive.

 

[lizardland]

I concider the study questionable because despite the data, somehow people interpret it as prebreaths are unnessasary. So clearly its poorly written. See part of science is defending your results and presenting them in such a way that even the dumbest amongst will agree with the findings and reccomendations. In this case the author failed to convince a lot of people.

Studies are not instructionals. It is not poorly written, if it was then this would more than likely have been flagged at peer review or by the journal editors. It presents the method, data, discussion and conclusions like any other scientific paper should do. If you think the study is bad then start a thread on Pubpeer or contact the publishers. Let us know how you get on.

If people want to make decisions based on that then it is the responsibility of the reader as to how they interpret and implement it, not the authors. You only have to look in the comments section of anything like Live Science or some other science news aggregator to see that most people do not know how to read scientific papers, don't really understand statistics and sure as hell don't have a grasp of basic critical thinking before opening their gobs. That's clear on everything from climate science to archaeology.