betterin the wob of an existing rebreather

**jmurba** · 13th June 2008, 09:30

Hi All,

I dive a home made that uses a dolphin loop.
there are photos on my web.
Well I'd like to better the wob as mutch as possible.
ok it will never be more then a dolphin loop I agree it is limited but it is my machine and I will never change.
the thing is that I have used a cell holder that is plugged into the dolphin outlet, and that is reducing the outlet diameter from 35 mm to 26 mm
for this reason I am machining an other sensor holder that will no reduce this diameter.

but will it effective ( a cell holder with 35mm inlet and outlet pipes) ?

I'have based my reasoning saying to myself a better wob can be achived in the dolphin configuration (I won't change the lung position) by eliminating my the restriction caused by the cell holder that in addition forces the gas to make a 90° turning that increases the breathing resistance.

as a matter of fact the dolphin hoses have a large diameter and it is a pity to place an obstacle between the bag and the mouth of the diver.

but what about the size of the dsv outlet hole ?

the hoses dimameter or section is large, and on the other hand the dsv hole (that is just before the mouth piece) is small.

so is it worth to have a large hose and no restriction between the bag and the dsv if the final hole is small ?....

is it because otherwise the hose itself would cause a resistance ?

what is the total resistance ? the sum of all parts resistance ?

an other paradox the dolphin outlet has 35mm hose diameter, 35 mm bag outlet diameter and 22 mm canister entry and outlet !!!

is it worth to have big hoses and small cannister entry and outlet ?

is it because there is a necessity to slow down the gas in the cannister to enhance dweling time ?

it is just a question because I won't make an other canister of course.

Well...MANY QUESTIONS SORRY FOR THE LONG MESSAGE;
regards

jean mi

OceanOpportunity · 14th June 2008, 02:08

the WOB questions out there have always interested me. Consider this...so much emphasis is placed on hose diameters, mushroom valves, CL placement, etc, but think about all of the other constructions in the loop. I dive a converted Dolphin, and have not had any issues with WOB at all. However a close look at the internals of the scrubber will show a very small opening on the sealed end of the scrubber..this is likely the smallest restriction point in the unit. It can be drilled out without affecting the structural integroty of the unit at all. 10mm variability on hoses, p-ports, etc...I dont buy that its too much of a factor..

Marc T · 14th June 2008, 12:45

Quote: (Originally Posted by jmurba)

Hi All,

I dive a home made that uses a dolphin loop.
there are photos on my web.
Well I'd like to better the wob as mutch as possible.
ok it will never be more then a dolphin loop I agree it is limited but it is my machine and I will never change.
the thing is that I have used a cell holder that is plugged into the dolphin outlet, and that is reducing the outlet diameter from 35 mm to 26 mm
for this reason I am machining an other sensor holder that will no reduce this diameter.

but will it effective ( a cell holder with 35mm inlet and outlet pipes) ?

I'have based my reasoning saying to myself a better wob can be achived in the dolphin configuration (I won't change the lung position) by eliminating my the restriction caused by the cell holder that in addition forces the gas to make a 90° turning that increases the breathing resistance.

as a matter of fact the dolphin hoses have a large diameter and it is a pity to place an obstacle between the bag and the mouth of the diver.

but what about the size of the dsv outlet hole ?

the hoses dimameter or section is large, and on the other hand the dsv hole (that is just before the mouth piece) is small.

so is it worth to have a large hose and no restriction between the bag and the dsv if the final hole is small ?....

is it because otherwise the hose itself would cause a resistance ?

what is the total resistance ? the sum of all parts resistance ?

an other paradox the dolphin outlet has 35mm hose diameter, 35 mm bag outlet diameter and 22 mm canister entry and outlet !!!

is it worth to have big hoses and small cannister entry and outlet ?

is it because there is a necessity to slow down the gas in the cannister to enhance dweling time ?

it is just a question because I won't make an other canister of course.

Well...MANY QUESTIONS SORRY FOR THE LONG MESSAGE;
regards

jean mi

Hi Jean Michel,

the effect on the wob due to a retriction greatly depend in is lengh, no only in is diameter.
without any math, very simple experience only blowing thrue different pipes with variious diameter, lengh or short restriction will show you that.
Im sure that if you isolate your "restrictive" cell holder and blow through it youll notice nothing comparing it to a pipe having the same MAXIMAL diameter.
As example, concerning blood flood in an artery ones can notice nothing if the diameter is no more reduce than 50%, and of course resitance to a flow is increased by the viscosity of the fluid.

As previously said by somehone ( JV perhaps ) dont take you the chou

Cheers

Marc

**jmurba** · 14th June 2008, 14:55

Quote: (Originally Posted by Marc T)

Hi Jean Michel,

the effect on the wob due to a retriction greatly depend in is lengh, no only in is diameter.
without any math, very simple experience only blowing thrue different pipes with variious diameter, lengh or short restriction will show you that.
Im sure that if you isolate your "restrictive" cell holder and blow through it youll notice nothing comparing it to a pipe having the same MAXIMAL diameter.
As example, concerning blood flood in an artery ones can notice nothing if the diameter is no more reduce than 50%, and of course resitance to a flow is increased by the viscosity of the fluid.

As previously said by somehone ( JV perhaps ) dont take you the chou

Cheers

Marc

Hi mark
In fact I have notice a difference since I addes one elbow in the expiration side and a cell holder elbow shaped in the inhalation side.
I think that a restriction located just between the inhalation bag and the inhalation hose really increases the wob, but I can't verify in cause I can't dive without cell holder of course.
I'll finish soon the new cell holder with no 90° turning and with 32mm diameter inlet and outlet pipe and let you know if it makes a difference or not.
I don't want to make things more complicated then they are (je me prend pas le chou encore que t'as peut être raison) I just do this cause I really have noticed a difference since I've installed this cell holder .
I' am asking all of those question cause I am about to built home made counter lung and of course bag ports and I wonder if it is worth making large diameters or if the standards one are just enough...
regards
jean mi

13th June 2008, 09:30	#1 (permalink)
jmurba wet bear Current Rebreather/s: Home Build Other Rebreather/s: Home Build Join Date: May 2006 Location: cannes france Posts: 862	betterin the wob of an existing rebreather Hi All, I dive a home made that uses a dolphin loop. there are photos on my web. Well I'd like to better the wob as mutch as possible. ok it will never be more then a dolphin loop I agree it is limited but it is my machine and I will never change. the thing is that I have used a cell holder that is plugged into the dolphin outlet, and that is reducing the outlet diameter from 35 mm to 26 mm for this reason I am machining an other sensor holder that will no reduce this diameter. but will it effective ( a cell holder with 35mm inlet and outlet pipes) ? I'have based my reasoning saying to myself a better wob can be achived in the dolphin configuration (I won't change the lung position) by eliminating my the restriction caused by the cell holder that in addition forces the gas to make a 90° turning that increases the breathing resistance. as a matter of fact the dolphin hoses have a large diameter and it is a pity to place an obstacle between the bag and the mouth of the diver. but what about the size of the dsv outlet hole ? the hoses dimameter or section is large, and on the other hand the dsv hole (that is just before the mouth piece) is small. so is it worth to have a large hose and no restriction between the bag and the dsv if the final hole is small ?.... is it because otherwise the hose itself would cause a resistance ? what is the total resistance ? the sum of all parts resistance ? an other paradox the dolphin outlet has 35mm hose diameter, 35 mm bag outlet diameter and 22 mm canister entry and outlet !!! is it worth to have big hoses and small cannister entry and outlet ? is it because there is a necessity to slow down the gas in the cannister to enhance dweling time ? it is just a question because I won't make an other canister of course. Well...MANY QUESTIONS SORRY FOR THE LONG MESSAGE; regards jean mi __________________ when will I be able to think about something else then spending hours underwater, when will I be normal ? http://web.mac.com/jmurba/Site_2/home.html http://web.mac.com/jmurba/Site_3/home.html
(Online)

14th June 2008, 02:08	#2 (permalink)
OceanOpportunity for a world of water Current Rebreather/s: Other CCR Dolphin Home Build Other Rebreather/s: Not Bought Yet Inspiration Classic Other CCR Dolphin Home Build Join Date: Nov 2006 Location: Providence, RI USA Posts: 544	Re: betterin the wob of an existing rebreather the WOB questions out there have always interested me. Consider this...so much emphasis is placed on hose diameters, mushroom valves, CL placement, etc, but think about all of the other constructions in the loop. I dive a converted Dolphin, and have not had any issues with WOB at all. However a close look at the internals of the scrubber will show a very small opening on the sealed end of the scrubber..this is likely the smallest restriction point in the unit. It can be drilled out without affecting the structural integroty of the unit at all. 10mm variability on hoses, p-ports, etc...I dont buy that its too much of a factor.. __________________ Michael Lombardi Oceans of Opportunity www.oceanopportunity.com Elected Director, Society for Human Performance in Extreme Environments MN'07, The Explorers Club Project Manager, Diving a Dream
(Offline)

14th June 2008, 12:45	#3 (permalink)
Marc T hell is in the details Current Rebreather/s: RB80 / Clone Home Build Other Rebreather/s: Not Bought Yet RB80 / Clone Home Build Join Date: Sep 2005 Location: FRANCE Carcassonne Posts: 485	Re: betterin the wob of an existing rebreather Quote: (Originally Posted by jmurba) Hi All, I dive a home made that uses a dolphin loop. there are photos on my web. Well I'd like to better the wob as mutch as possible. ok it will never be more then a dolphin loop I agree it is limited but it is my machine and I will never change. the thing is that I have used a cell holder that is plugged into the dolphin outlet, and that is reducing the outlet diameter from 35 mm to 26 mm for this reason I am machining an other sensor holder that will no reduce this diameter. but will it effective ( a cell holder with 35mm inlet and outlet pipes) ? I'have based my reasoning saying to myself a better wob can be achived in the dolphin configuration (I won't change the lung position) by eliminating my the restriction caused by the cell holder that in addition forces the gas to make a 90° turning that increases the breathing resistance. as a matter of fact the dolphin hoses have a large diameter and it is a pity to place an obstacle between the bag and the mouth of the diver. but what about the size of the dsv outlet hole ? the hoses dimameter or section is large, and on the other hand the dsv hole (that is just before the mouth piece) is small. so is it worth to have a large hose and no restriction between the bag and the dsv if the final hole is small ?.... is it because otherwise the hose itself would cause a resistance ? what is the total resistance ? the sum of all parts resistance ? an other paradox the dolphin outlet has 35mm hose diameter, 35 mm bag outlet diameter and 22 mm canister entry and outlet !!! is it worth to have big hoses and small cannister entry and outlet ? is it because there is a necessity to slow down the gas in the cannister to enhance dweling time ? it is just a question because I won't make an other canister of course. Well...MANY QUESTIONS SORRY FOR THE LONG MESSAGE; regards jean mi Hi Jean Michel, the effect on the wob due to a retriction greatly depend in is lengh, no only in is diameter. without any math, very simple experience only blowing thrue different pipes with variious diameter, lengh or short restriction will show you that. Im sure that if you isolate your "restrictive" cell holder and blow through it youll notice nothing comparing it to a pipe having the same MAXIMAL diameter. As example, concerning blood flood in an artery ones can notice nothing if the diameter is no more reduce than 50%, and of course resitance to a flow is increased by the viscosity of the fluid. As previously said by somehone ( JV perhaps ) dont take you the chou Cheers Marc
(Offline)

14th June 2008, 14:55	#4 (permalink)
jmurba wet bear Current Rebreather/s: Home Build Other Rebreather/s: Home Build Join Date: May 2006 Location: cannes france Posts: 862	Re: betterin the wob of an existing rebreather Quote: (Originally Posted by Marc T) Hi Jean Michel, the effect on the wob due to a retriction greatly depend in is lengh, no only in is diameter. without any math, very simple experience only blowing thrue different pipes with variious diameter, lengh or short restriction will show you that. Im sure that if you isolate your "restrictive" cell holder and blow through it youll notice nothing comparing it to a pipe having the same MAXIMAL diameter. As example, concerning blood flood in an artery ones can notice nothing if the diameter is no more reduce than 50%, and of course resitance to a flow is increased by the viscosity of the fluid. As previously said by somehone ( JV perhaps ) dont take you the chou Cheers Marc Hi mark In fact I have notice a difference since I addes one elbow in the expiration side and a cell holder elbow shaped in the inhalation side. I think that a restriction located just between the inhalation bag and the inhalation hose really increases the wob, but I can't verify in cause I can't dive without cell holder of course. I'll finish soon the new cell holder with no 90° turning and with 32mm diameter inlet and outlet pipe and let you know if it makes a difference or not. I don't want to make things more complicated then they are (je me prend pas le chou encore que t'as peut être raison) I just do this cause I really have noticed a difference since I've installed this cell holder . I' am asking all of those question cause I am about to built home made counter lung and of course bag ports and I wonder if it is worth making large diameters or if the standards one are just enough... regards jean mi __________________ when will I be able to think about something else then spending hours underwater, when will I be normal ? http://web.mac.com/jmurba/Site_2/home.html http://web.mac.com/jmurba/Site_3/home.html
(Online)

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode