Inner Diameter of breathing hoses

onetime · 28th April 2005, 11:56

Just wondering what the different breathing hose inner diameters were for the various rebreathers. From pics it seems that some are considerably larger than others. Any opinions on whether larger diameters are better/worse than smaller diameters and why?

***schford*** · 28th April 2005, 11:58

I believe that larger is better due to decreased WOB...

Stuart

***Beanie*** · 28th April 2005, 12:05

Inspiration 33-35mm I think measured them last night for Simon A

onetime · 28th April 2005, 13:28

Quote: (Originally Posted by schford)

I believe that larger is better due to decreased WOB...

Stuart

A comment I read from Tom Mount about the smaller hose daimeters on the Nemesis indicated that his initial concern around the smaller diameter wasn't justified. Of course, I don't know how the Nemesis hoses compare to others. The Meg appears to have larger than "typical" hoses.

Mdemon · 28th April 2005, 13:42

Large hose might mean lower WOB but also higher loop volume and therefore buoyancy.

Just a thought, but it must be a function of bore x length, as the pipe on the inspo scrubber seems smaller than the hose...

***schford*** · 28th April 2005, 13:45

Quote: (Originally Posted by Mdemon)

Large hose might mean lower WOB but also higher loop volume and therefore buoyancy.

Depends on the weight of the hose material and also length of hoses...

For instance Meg has fairly large bore hoses but very short so no need of hose weights....

Stuart

***caveseeker7*** · 28th April 2005, 16:24

The diameter of anything within the loop has an influece on WOB as well as gas velocity.

Mdemon · 28th April 2005, 16:29

Quote: (Originally Posted by schford)

Depends on the weight of the hose material and also length of hoses...

For instance Meg has fairly large bore hoses but very short so no need of hose weights....

Stuart

Good point.

onetime · 28th April 2005, 17:17

Quote: (Originally Posted by caveseeker7)

The diameter of anything within the loop has an influece on WOB as well as gas velocity.

Seems it would have a relationship to the likelihood of CO2 buildup as well. Larger diameter could mean incomplete transfer of gas through the loop, no?

***caveseeker7*** · 28th April 2005, 17:32

Am not sure what you mean with incomplete transfer of gas.
Velocity is important in regards dwell time as well as condensation.

If the gas moves slowly through the scrubber bed CO2 will be absorbed better than at higher speed. The gas will have more time to condensate, so if the condensation points are properly placed the chances of 'wet sensors' are greatly reduced.

That is also one of the main advantages of dual counterlungs over single ones.
The gas flows slows or even stops in a breathing cycle further increasing dwell and condensation times.

28th April 2005, 11:56	#1 (permalink)
onetime Classic KISSer #138 Current Rebreather/s: Classic Kiss Other Rebreather/s: Join Date: Mar 2005 Location: US, NJ Posts: 673	Inner Diameter of breathing hoses Just wondering what the different breathing hose inner diameters were for the various rebreathers. From pics it seems that some are considerably larger than others. Any opinions on whether larger diameters are better/worse than smaller diameters and why?
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28th April 2005, 11:58	#2 (permalink)
*schford* Despotic Overlord Current Rebreather/s: Megalodon Sport Kiss Other Rebreather/s: Join Date: Jan 2005 Location: London, UK Posts: 3,562	I believe that larger is better due to decreased WOB... Stuart
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28th April 2005, 12:05	#3 (permalink)
*Beanie* give a man an inch....... Current Rebreather/s: Inspiration Classic Other Rebreather/s: Inspiration Vision Join Date: Jan 2005 Location: In da house! yeah baby! Posts: 3,174	Inspiration 33-35mm I think measured them last night for Simon A __________________ Beanie Gallery Admin & Library Assistant. www.outlawdivers.org.uk www.beandiving.co.uk www.beanengineering.co.uk
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28th April 2005, 13:28	#4 (permalink)
onetime Classic KISSer #138 Current Rebreather/s: Classic Kiss Other Rebreather/s: Join Date: Mar 2005 Location: US, NJ Posts: 673	Quote: (Originally Posted by schford) I believe that larger is better due to decreased WOB... Stuart A comment I read from Tom Mount about the smaller hose daimeters on the Nemesis indicated that his initial concern around the smaller diameter wasn't justified. Of course, I don't know how the Nemesis hoses compare to others. The Meg appears to have larger than "typical" hoses.
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28th April 2005, 13:42	#5 (permalink)
Mdemon SiegeEngine II Current Rebreather/s: Inspiration Classic Home Build Other Rebreather/s: Inspiration Classic Home Build Join Date: Feb 2007 Location: SWUK Posts: 1,927	Large hose might mean lower WOB but also higher loop volume and therefore buoyancy. Just a thought, but it must be a function of bore x length, as the pipe on the inspo scrubber seems smaller than the hose... __________________ www.southwestmafia.com "small minds talk about people, Average Minds Talk About Events, GREAT MINDS TALK ABOUT IDEAS!" The WRONG Attitude will get you killed. "Once the agenda-monkeys and perfect-worlders have moved on, perhaps we can do some diving?"
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28th April 2005, 13:45	#6 (permalink)
*schford* Despotic Overlord Current Rebreather/s: Megalodon Sport Kiss Other Rebreather/s: Join Date: Jan 2005 Location: London, UK Posts: 3,562	Quote: (Originally Posted by Mdemon) Large hose might mean lower WOB but also higher loop volume and therefore buoyancy. Depends on the weight of the hose material and also length of hoses... For instance Meg has fairly large bore hoses but very short so no need of hose weights.... Stuart
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28th April 2005, 16:24	#7 (permalink)
*caveseeker7* Who loves ya, baby Current Rebreather/s: Sport Kiss Other Rebreather/s: Prism Topaz Join Date: Jan 2005 Location: Too far from Neverland Posts: 5,451	The diameter of anything within the loop has an influece on WOB as well as gas velocity. __________________ Cheers Stefan "Political Correctness is a doctrine, fostered by a delusional, illogical minority, and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a turd by the clean end.!"
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28th April 2005, 16:29	#8 (permalink)
Mdemon SiegeEngine II Current Rebreather/s: Inspiration Classic Home Build Other Rebreather/s: Inspiration Classic Home Build Join Date: Feb 2007 Location: SWUK Posts: 1,927	Quote: (Originally Posted by schford) Depends on the weight of the hose material and also length of hoses... For instance Meg has fairly large bore hoses but very short so no need of hose weights.... Stuart Good point. __________________ www.southwestmafia.com "small minds talk about people, Average Minds Talk About Events, GREAT MINDS TALK ABOUT IDEAS!" The WRONG Attitude will get you killed. "Once the agenda-monkeys and perfect-worlders have moved on, perhaps we can do some diving?"
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28th April 2005, 17:17	#9 (permalink)
onetime Classic KISSer #138 Current Rebreather/s: Classic Kiss Other Rebreather/s: Join Date: Mar 2005 Location: US, NJ Posts: 673	Quote: (Originally Posted by caveseeker7) The diameter of anything within the loop has an influece on WOB as well as gas velocity. Seems it would have a relationship to the likelihood of CO2 buildup as well. Larger diameter could mean incomplete transfer of gas through the loop, no?
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28th April 2005, 17:32	#10 (permalink)
*caveseeker7* Who loves ya, baby Current Rebreather/s: Sport Kiss Other Rebreather/s: Prism Topaz Join Date: Jan 2005 Location: Too far from Neverland Posts: 5,451	Am not sure what you mean with incomplete transfer of gas. Velocity is important in regards dwell time as well as condensation. If the gas moves slowly through the scrubber bed CO2 will be absorbed better than at higher speed. The gas will have more time to condensate, so if the condensation points are properly placed the chances of 'wet sensors' are greatly reduced. That is also one of the main advantages of dual counterlungs over single ones. The gas flows slows or even stops in a breathing cycle further increasing dwell and condensation times. __________________ Cheers Stefan "Political Correctness is a doctrine, fostered by a delusional, illogical minority, and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a turd by the clean end.!"
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