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paulraymaekers · 3rd May 2007, 08:34

Quote: (Originally Posted by Drmike)

Hi Im trying to get my head around this issue - can anyone help?

Ive heard it said that using 2 CLs will increase the dwell time in the scrubber but i dont get it.

Surely mass flow rate is constant scrubber volume is constant so what am I missing? why isnt gas velocity thru scrubber constant?

I get that having 2 cl gives slightly better wob but just how significant is that? Alex your design is single CL? Titan is single, MK16 single.

Chatting with RickS I know hes using only one CL in his sidemount and hes using that at 175m....

Any info pros cons appreciated

here we go again mike, dwell time.... :-)

2 counterlungs, IF WELL POSITIONED, increase dwell time

one counterlung: only flow trough the scrubber half the total breathing time (double average gasspeed) eighter only during inhale (counterlung placed befor scrubber in loop) eighter only during exhale (counterlung placed after the scrubber in the loop)

dual counterlung, can take advantage of hydrostatic balancing in the system:
imagine both counterlungs are at the same height in the water: means waterpressure will try to level the gasvolumes in both lungs (lowest part of the gasvolume in both lungs at same height in the water)

so when you exhale, half of the expired gas will go trough the scrubber to the 'inhale-counterlung' the other half will stay in the 'exhale-counterlung', because waterpressure always trys to level the bottom of both counterlungs
meaning gasspeed trough the scrubber will be half of the single-lung system
inhale: same scenario: both lungs will be emptied at the same time, so half the gas comes from exhale lung, trough the scrubber now, half from the inhale lung, already scrubbed

now if the counterlungs are not at the same height, completely different story: one will be filled/emptied always first, (so no equal distribution between inhale and exhale) because waterpressure will always push the gas in the highest volume..

regards
paul

3rd May 2007, 08:34	#2 (permalink)
paulraymaekers rEvo's daddy Current Rebreather/s: rEvo Other CCR Home Build Other Rebreather/s: rEvo Other CCR Home Build Join Date: May 2005 Location: belgium Posts: 1,498	Re: one or two CL and scrubber dwell time Quote: (Originally Posted by Drmike) Hi Im trying to get my head around this issue - can anyone help? Ive heard it said that using 2 CLs will increase the dwell time in the scrubber but i dont get it. Surely mass flow rate is constant scrubber volume is constant so what am I missing? why isnt gas velocity thru scrubber constant? I get that having 2 cl gives slightly better wob but just how significant is that? Alex your design is single CL? Titan is single, MK16 single. Chatting with RickS I know hes using only one CL in his sidemount and hes using that at 175m.... Any info pros cons appreciated here we go again mike, dwell time.... :-) 2 counterlungs, IF WELL POSITIONED, increase dwell time one counterlung: only flow trough the scrubber half the total breathing time (double average gasspeed) eighter only during inhale (counterlung placed befor scrubber in loop) eighter only during exhale (counterlung placed after the scrubber in the loop) dual counterlung, can take advantage of hydrostatic balancing in the system: imagine both counterlungs are at the same height in the water: means waterpressure will try to level the gasvolumes in both lungs (lowest part of the gasvolume in both lungs at same height in the water) so when you exhale, half of the expired gas will go trough the scrubber to the 'inhale-counterlung' the other half will stay in the 'exhale-counterlung', because waterpressure always trys to level the bottom of both counterlungs meaning gasspeed trough the scrubber will be half of the single-lung system inhale: same scenario: both lungs will be emptied at the same time, so half the gas comes from exhale lung, trough the scrubber now, half from the inhale lung, already scrubbed now if the counterlungs are not at the same height, completely different story: one will be filled/emptied always first, (so no equal distribution between inhale and exhale) because waterpressure will always push the gas in the highest volume.. regards paul __________________ www.rEvo-rebreathers.com .... the earth is flat, Elvis is alive, and radial scrubbers give longer dwell time than axials... Last edited by paulraymaekers : 3rd May 2007 at 08:36.
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