Tempstik and Pre-Breathe

Tim Cashman · 3rd August 2006, 14:25

Q1: Who does a pre - breathe before diving??
I've used a standard inspiration for 6 yrs and got into the habit of just doing a few quick wiffs to make sure the solenoid fires and shuts off ok, then launch myself into the ogin (so far with no detrimental effects).
So when I obtained a vision and continued with my tried and tested technique imagine my horror when I downloaded the dive later.
The tempstick told me:
At the surface the bottom 1/8th of the stack was warm and the rest was cold. ie not reacting.
(I'm swimming for the shot about now)
During the descent the bottom 2nd 8th was the only warm section.
(I'm clipping my tag into the D/C station at about 60m now)
At the bottom, the middle 2/8ths were warm and the rest was cold. ie not reacting.
(I'm switching to high setpoint and about to ferret around the wreck at 120m)
5 mins later the top 3/4 was all warm ie the scrubber was now functioning normally.
(I'm scootering around the bow in 125m about now)
Moral of story.
Always do a pre breathe and don't get complacent like I did.

Mixaddict · 3rd August 2006, 14:55

The prebreath is critical for a number of reasons besides just the warming up of the scrubber - double checking to make sure there are no obvious problems with the gas, checking for solenoid operation, checking for channeling, O2 sensor slowness or failure, etc. etc. etc.

This should be happening regardless of whether you have a temp stick or not.

**nigelh** · 3rd August 2006, 14:56

Quote: (Originally Posted by Tim Cashman)

The tempstick told me:
At the surface the bottom 1/8th of the stack was warm and the rest was cold. ie not reacting.

If, because it was cold, it was not reacting it would never get warm and so never react.

It is reacting nicely, it is generating heat and will warm up given time. The reaction slowly heats things up and, while we agree the reaction runs a bit better when warm, it still runs. It always worked for you before.

I still think a pre-breath is a good idea.

PoulO · 3rd August 2006, 15:13

I usually breathe until the tempstick starts reacting which is about 2-4 minutes. In my experience it is normal that only the bottom of the tempstick react in shallow water. At shallow only a small portion of the scrubber is warm. A bigger part of the scrubber is in use during the dive but at deco only a small part of the scrubber is active.

Tim Cashman · 3rd August 2006, 15:44

The point is it takes at least 5 minutes to get the reaction fully underway and 120M+ is not the place to do it.

So who does a 5 minute+ pre breathe before jumping off the boat?

***Beanie*** · 3rd August 2006, 15:50

Quote: (Originally Posted by Tim Cashman)

The point is it takes at least 5 minutes to get the reaction fully underway and 120M+ is not the place to do it.

So who does a 5 minute+ pre breathe before jumping off the boat?

Me for one no temp stick but I do a good 5 mins pre breathe while putting fins on clipping on reels and stages etc.

**nigelh** · 3rd August 2006, 16:03

Quote: (Originally Posted by Tim Cashman)

The point is it takes at least 5 minutes to get the reaction fully underway?

This depends what you mean by 'Fully Underway'.

Thermally settled and showing on a temp-stick may take 5 minutes but unless the 'lime is very cold and very dry the reaction is scrubbing 100% of the CO2 from the first breath. I'll settle for that at any depth.

***Decodiver*** · 3rd August 2006, 17:01

Quote: (Originally Posted by Tim Cashman)

Q1: Who does a pre - breathe before diving??

Tim,

I am ex-military and was taught to prebreathe right from the start.

So add me and all of my ex-students who don't want a ferkin' good kicking!!

Have some green for your post as I believe it clearly demonstrates how to design out a problem from CCR diving.

I for one will be copying your post and using it on my courses.

Nigel's comments are valid, however a prebreathe is fundamental to discover a loop/gas problem before getting in the water.

People who do not conduct a proper prebreathe are just plain dumb.

Thanks.

Cheers,

Dave Cooper.

Tim Cashman · 3rd August 2006, 17:14

Yeah I was taught to pre breathe too but there was no one around to kick me until the tempstik learned me how stupid I had become.

rusty · 3rd August 2006, 17:34

I had a CCR cave class with Kevin Gurr last year and make sure to do a pre breathe before every dive on the surface for 5 minutes after Kevin explained some accidents he has seen.
I also make sure to do it on land before I get on the boat in case there is a problem/channeling and I need to take the rig apart.
Its important to pinch your nose as a lot of people end up involuntarily breathing out their nose while doing a pre breathe. I cant take credit for any of this as Kevin was adamant about the pre breathe and how it can definately help prevent certain problems from arising at inopportune moments.

3rd August 2006, 14:25	#1 (permalink)
Tim Cashman RBW Member Current Rebreather/s: Inspiration Classic Other Rebreather/s: Join Date: Aug 2005 Posts: 55	Tempstik and Pre-Breathe Q1: Who does a pre - breathe before diving?? I've used a standard inspiration for 6 yrs and got into the habit of just doing a few quick wiffs to make sure the solenoid fires and shuts off ok, then launch myself into the ogin (so far with no detrimental effects). So when I obtained a vision and continued with my tried and tested technique imagine my horror when I downloaded the dive later. The tempstick told me: At the surface the bottom 1/8th of the stack was warm and the rest was cold. ie not reacting. (I'm swimming for the shot about now) During the descent the bottom 2nd 8th was the only warm section. (I'm clipping my tag into the D/C station at about 60m now) At the bottom, the middle 2/8ths were warm and the rest was cold. ie not reacting. (I'm switching to high setpoint and about to ferret around the wreck at 120m) 5 mins later the top 3/4 was all warm ie the scrubber was now functioning normally. (I'm scootering around the bow in 125m about now) Moral of story. Always do a pre breathe and don't get complacent like I did. Last edited by Tim Cashman : 3rd August 2006 at 14:28.
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3rd August 2006, 14:55	#2 (permalink)
Mixaddict Always Learning! Current Rebreather/s: Inspiration Vision Evolution Other CCR Other Rebreather/s: Inspiration Classic Other CCR Join Date: Jan 2006 Location: Draper, Utah USA Posts: 508	Re: Tempstik and Pre-Breathe The prebreath is critical for a number of reasons besides just the warming up of the scrubber - double checking to make sure there are no obvious problems with the gas, checking for solenoid operation, checking for channeling, O2 sensor slowness or failure, etc. etc. etc. This should be happening regardless of whether you have a temp stick or not.
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3rd August 2006, 14:56	#3 (permalink)
nigelh New member Current Rebreather/s: Inspiration Vision Other CCR Other Rebreather/s: Inspiration Classic Other CCR Join Date: Mar 2005 Location: Brighton, Sussex, UK Posts: 874	Re: Tempstik and Pre-Breathe Quote: (Originally Posted by Tim Cashman) The tempstick told me: At the surface the bottom 1/8th of the stack was warm and the rest was cold. ie not reacting. If, because it was cold, it was not reacting it would never get warm and so never react. It is reacting nicely, it is generating heat and will warm up given time. The reaction slowly heats things up and, while we agree the reaction runs a bit better when warm, it still runs. It always worked for you before. I still think a pre-breath is a good idea. __________________ nigelh
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3rd August 2006, 15:13	#4 (permalink)
PoulO New Member Current Rebreather/s: Evolution Other Rebreather/s: Megalodon Join Date: Dec 2005 Location: Copenhagen Denmark Posts: 25	Re: Tempstik and Pre-Breathe I usually breathe until the tempstick starts reacting which is about 2-4 minutes. In my experience it is normal that only the bottom of the tempstick react in shallow water. At shallow only a small portion of the scrubber is warm. A bigger part of the scrubber is in use during the dive but at deco only a small part of the scrubber is active.
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3rd August 2006, 15:44	#5 (permalink)
Tim Cashman RBW Member Current Rebreather/s: Inspiration Classic Other Rebreather/s: Join Date: Aug 2005 Posts: 55	Re: Tempstik and Pre-Breathe The point is it takes at least 5 minutes to get the reaction fully underway and 120M+ is not the place to do it. So who does a 5 minute+ pre breathe before jumping off the boat?
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3rd August 2006, 15:50	#6 (permalink)
*Beanie* Gallery Administrator Current Rebreather/s: Inspiration Classic Other Rebreather/s: Inspiration Vision Join Date: Jan 2005 Location: In da house! yeah baby! Posts: 3,292	Re: Tempstik and Pre-Breathe Quote: (Originally Posted by Tim Cashman) The point is it takes at least 5 minutes to get the reaction fully underway and 120M+ is not the place to do it. So who does a 5 minute+ pre breathe before jumping off the boat? Me for one no temp stick but I do a good 5 mins pre breathe while putting fins on clipping on reels and stages etc. __________________ Beanie Gallery Admin & Library Assistant. www.outlawdivers.org.uk www.beandiving.co.uk www.beanengineering.co.uk
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3rd August 2006, 16:03	#7 (permalink)
nigelh New member Current Rebreather/s: Inspiration Vision Other CCR Other Rebreather/s: Inspiration Classic Other CCR Join Date: Mar 2005 Location: Brighton, Sussex, UK Posts: 874	Re: Tempstik and Pre-Breathe Quote: (Originally Posted by Tim Cashman) The point is it takes at least 5 minutes to get the reaction fully underway? This depends what you mean by 'Fully Underway'. Thermally settled and showing on a temp-stick may take 5 minutes but unless the 'lime is very cold and very dry the reaction is scrubbing 100% of the CO2 from the first breath. I'll settle for that at any depth. __________________ nigelh
(Online)

3rd August 2006, 17:01	#8 (permalink)
*Decodiver* Administrator Current Rebreather/s: Other CCR Other Rebreather/s: Other CCR Join Date: Jan 2005 Location: Geneva Posts: 2,190	Re: Tempstik and Pre-Breathe Quote: (Originally Posted by Tim Cashman) Q1: Who does a pre - breathe before diving?? Tim, I am ex-military and was taught to prebreathe right from the start. So add me and all of my ex-students who don't want a ferkin' good kicking!! Have some green for your post as I believe it clearly demonstrates how to design out a problem from CCR diving. I for one will be copying your post and using it on my courses. Nigel's comments are valid, however a prebreathe is fundamental to discover a loop/gas problem before getting in the water. People who do not conduct a proper prebreathe are just plain dumb. Thanks. Cheers, Dave Cooper. __________________ CCR/OC Trimix Instructor Trainer CCR Training to Mixed Gas in Switzerland, France, UK & Germany on Megalodon/COPIS-Megalodon/KISS/Sport KISS/Ouroboros/rEvo/Inspiration/Evolution/Sentinel www.zerogravitydiving.com Rebreather World Terms & Conditions Last edited by Decodiver : 3rd August 2006 at 17:03.
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3rd August 2006, 17:14	#9 (permalink)
Tim Cashman RBW Member Current Rebreather/s: Inspiration Classic Other Rebreather/s: Join Date: Aug 2005 Posts: 55	Re: Tempstik and Pre-Breathe Yeah I was taught to pre breathe too but there was no one around to kick me until the tempstik learned me how stupid I had become.
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3rd August 2006, 17:34	#10 (permalink)
rusty RBW Member Current Rebreather/s: Evolution Sport Kiss Classic Kiss rEvo Other Rebreather/s: Ouroboros rEvo Join Date: Sep 2005 Location: USA,Monterey,CA Posts: 178	Re: Tempstik and Pre-Breathe I had a CCR cave class with Kevin Gurr last year and make sure to do a pre breathe before every dive on the surface for 5 minutes after Kevin explained some accidents he has seen. I also make sure to do it on land before I get on the boat in case there is a problem/channeling and I need to take the rig apart. Its important to pinch your nose as a lot of people end up involuntarily breathing out their nose while doing a pre breathe. I cant take credit for any of this as Kevin was adamant about the pre breathe and how it can definately help prevent certain problems from arising at inopportune moments. __________________ Best Regards, Russ Sanoian U/W Sales 831-645-1082 www.backscatter.com Breaching the Boundaries of the Abyss With Underwater Imaging Innovations Last edited by rusty : 3rd August 2006 at 18:07.
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