Rebreather World - View Single Post - General question

dave t · 1st March 2007, 16:22

Quote: (Originally Posted by jepuskar)

Ok, I just had my first pool dives on a couple units last weekend and have I have been soaking the experience in...not quite obsessed yet, but getting there...it wasnt a class, but just an experience.

Please feel free to slap me if I'm wrong on these points/observations..but if you are going to slap me atleast help me.

1) Your loop is just like your BC...the more air in it the more it has an affect on your buoyancy..meaning injecting more gas into the loop is going to increase your lift in the water column.

2) If #1 is correct that would mean that if you are nuetrally buoyant and not changing depth...if oxygen is not being injected into your loop to keep your setpoint than you will become negative. Less loop volume means not as much lift...keeping in mind no adjustments to the BC and constant depth.

3) When ascending, besides venting the BC/drysuit...you can exhale out of your nose to lower the loop volume as the gas in it expands. Exhaling out of the mouthpiece is ok as well. If you have an OTS CL than as you exhale you pull the dump cord to let the gas escape.

Do I have the correct understanding?

Thank you.

Jason

1 yes true but you will only need to add gas (diluent) as you descend to compensate for the increase in pressure that will colapse the lung. we practise a skill called "minimum loop volume" to minimise among other things the effects of buoyancy

2 yes but more importantly if no 02 is added you will die!.if o2 is added to match metabolism the volume will stay the same.

3 Its always better to use your mouth to dump as you ascend, you get better control

HTH

Dave

1st March 2007, 16:22	#2 (permalink)
dave t Custom Title Allowed! Current Rebreather/s: Inspiration Classic Inspiration Vision Evolution Sport Kiss Classic Kiss Dolphin Ray Azimuth Home Build Other Rebreather/s: Dolphin Ray Azimuth Home Build Join Date: May 2005 Location: UK Posts: 654	Re: General question - loop volume and buoyancy Quote: (Originally Posted by jepuskar) Ok, I just had my first pool dives on a couple units last weekend and have I have been soaking the experience in...not quite obsessed yet, but getting there...it wasnt a class, but just an experience. Please feel free to slap me if I'm wrong on these points/observations..but if you are going to slap me atleast help me. 1) Your loop is just like your BC...the more air in it the more it has an affect on your buoyancy..meaning injecting more gas into the loop is going to increase your lift in the water column. 2) If #1 is correct that would mean that if you are nuetrally buoyant and not changing depth...if oxygen is not being injected into your loop to keep your setpoint than you will become negative. Less loop volume means not as much lift...keeping in mind no adjustments to the BC and constant depth. 3) When ascending, besides venting the BC/drysuit...you can exhale out of your nose to lower the loop volume as the gas in it expands. Exhaling out of the mouthpiece is ok as well. If you have an OTS CL than as you exhale you pull the dump cord to let the gas escape. Do I have the correct understanding? Thank you. Jason 1 yes true but you will only need to add gas (diluent) as you descend to compensate for the increase in pressure that will colapse the lung. we practise a skill called "minimum loop volume" to minimise among other things the effects of buoyancy 2 yes but more importantly if no 02 is added you will die!.if o2 is added to match metabolism the volume will stay the same. 3 Its always better to use your mouth to dump as you ascend, you get better control HTH Dave
(Offline)