How many hours from a Prism with 19 cft tanks?

***jradomski*** · 3rd August 2007, 23:07

Quote: (Originally Posted by warjarrett)

I think I need to specify more assumptions. The 19s will be full to their maximum rated capacity (not short-filled), I will have no bail-out bottle (so I need to surface with an emergency contigent reserve), and my drysuit and buoyancy bladder have no separate supply (just use gas from the diluent tank). Then, the next question will be, well, how much more time will I get if I do bring a separate bailout bottle?

Don't ever dive a Rebreather without bailout its just asking for trouble.. Onboard gas is not bailout, It is acceptable for an intermediate gas while you get onto your bailout gas....
I ALWAYS carry at a minimum of an al 40 for bailout (for recreational depths a 30 would do, but a 40 sits much nicer on my body because its a longer cylinder..)

warjarrett · 19th August 2007, 22:53

Here I am again, now responding to my own thread. I just finished a week of training with Jeff Bozanic. And, one thing I learned was that I will ALWAYS carry a bail-out bottle. For a dive to 90-100 ft, the size of the bail-out MUST BE at least 19 cu.ft., to allow for some time to get oriented (if an emergency occurs), a normal ascent, and a 3 minute safety stop. So, now I change my assumptions, but the question still stands >>> Assuming I can fully use-up a pair of 19 cu.ft. cylinders, how many dive-hours can I roughly expect to get from a single pair? I must add these conditions also: no heavy work-load and average physical condition. <<< Ok, my current best answer is this: The latest rule-of-thumb I read is about 500 psi of each (O2 and dill) for an average 1 1/2 hour dive above 100 ft (keep in mind that O2 consumption has nothing to do with depth). But you must have plenty of left-over dil, because you never know when you might unexpectedly need more than usual. So I am thinking that I can dive the O2 right down to 200-300 psi, but should never let the dil get below 500 psi. What does everyone think of these as just rough ideas?

warjarrett · 19th August 2007, 23:01

Oh, one more thing. Jeff Bozanic DOES NOT recommend diving with a 19 cu. ft. bail-out bottle under any circumstances. This was MY idea, based on what I learned during the theory portion of his lectures. So, NOBODY should take my word for it about this size bail-out. BIGGER IS BETTER...um, I mean... BIGGER IS SAFER.

dive2dive2000 · 19th August 2007, 23:21

Quote: (Originally Posted by warjarrett)

Here I am again, now responding to my own thread. I just finished a week of training with Jeff Bozanic. And, one thing I learned was that I will ALWAYS carry a bail-out bottle. For a dive to 90-100 ft, the size of the bail-out MUST BE at least 19 cu.ft., to allow for some time to get oriented (if an emergency occurs), a normal ascent, and a 3 minute safety stop. So, now I change my assumptions, but the question still stands >>> Assuming I can fully use-up a pair of 19 cu.ft. cylinders, how many dive-hours can I roughly expect to get from a single pair? I must add these conditions also: no heavy work-load and average physical condition. <<< Ok, my current best answer is this: The latest rule-of-thumb I read is about 500 psi of each (O2 and dill) for an average 1 1/2 hour dive above 100 ft (keep in mind that O2 consumption has nothing to do with depth). But you must have plenty of left-over dil, because you never know when you might unexpectedly need more than usual. So I am thinking that I can dive the O2 right down to 200-300 psi, but should never let the dil get below 500 psi. What does everyone think of these as just rough ideas?

I have the ability to use off board plug in, but lets not go there.For just starting out I would always try and fill my dil bottle. As the hrs progress and you learn your rig then you will know what is correct and what is not.

As far as O2 I think you are cutting it way close. I would never jump in with O2 psi under 1000, unless I had the ability for off board plug in (which I do). Just fill your bottles often dive and learn your kit everything else will fall into place.

i

DaveC · 20th August 2007, 11:02

Quote: (Originally Posted by dive2dive2000)

As far as O2 I think you are cutting it way close. I would never jump in with O2 psi under 1000, unless I had the ability for off board plug in (which I do). Just fill your bottles often dive and learn your kit everything else will fall into place.

I think common sense comes into play here. What Setpoint, what depth, duration, etc... Just have to watch the pressure more closely when starting a dive with this kind of volume.

warjarrett · 9th September 2007, 22:44

I just finished my first dive after training, and here is what I came up with. I dove a set point of 1.0, but manually kept PO2 between 1.0 and 1.2 (mostly 1.2). Max depth was 80 feet, and duration was 45 minutes. I was diving with OC divers, so we went up and down quite a bit (exhaling through my nose every ascent and using more dil every descent - good practice), and had to end the dive based on their air consumption. I was VERY tired after just this one dive... beginners discomfort I guess, and chose not to do a second. I did carry a 19 cuft bailout, went on it once just for practice. I used about 500 psi O2 and 1000 psi Dil, from 19s (3000 psi fills). I hope this consumption will go down as I get more dives in. At this rate of dil usage, I can only get 2 dives out of a dil tank fill -- there is no air compressor aboard the boat I dive.

**Dsix36** · 10th September 2007, 00:02

Quote: (Originally Posted by warjarrett)

I just finished my first dive after training, and here is what I came up with. I dove a set point of 1.0, but manually kept PO2 between 1.0 and 1.2 (mostly 1.2). Max depth was 80 feet, and duration was 45 minutes. I was diving with OC divers, so we went up and down quite a bit (exhaling through my nose every ascent and using more dil every descent - good practice), and had to end the dive based on their air consumption. I was VERY tired after just this one dive... beginners discomfort I guess, and chose not to do a second. I did carry a 19 cuft bailout, went on it once just for practice. I used about 500 psi O2 and 1000 psi Dil, from 19s (3000 psi fills). I hope this consumption will go down as I get more dives in. At this rate of dil usage, I can only get 2 dives out of a dil tank fill -- there is no air compressor aboard the boat I dive.

I don't dive a Prisim, but my consumptions were a lot like yours when I first certified. I only have about 8 dives more than you do. Today I did 4 dives with a total bottom time of 3 hour and 55 minutes. I used 1000psi of Oxy and 900psi of Dil. I use Al20's and the dives were 60-80 ft deep. Your consumption will get better too.

***diverklondike*** · 10th September 2007, 00:06

Quote: (Originally Posted by warjarrett)

Here I am again, now responding to my own thread. I just finished a week of training with Jeff Bozanic. And, one thing I learned was that I will ALWAYS carry a bail-out bottle. For a dive to 90-100 ft, the size of the bail-out MUST BE at least 19 cu.ft., to allow for some time to get oriented (if an emergency occurs), a normal ascent, and a 3 minute safety stop. So, now I change my assumptions, but the question still stands >>> Assuming I can fully use-up a pair of 19 cu.ft. cylinders, how many dive-hours can I roughly expect to get from a single pair? I must add these conditions also: no heavy work-load and average physical condition. <<< Ok, my current best answer is this: The latest rule-of-thumb I read is about 500 psi of each (O2 and dill) for an average 1 1/2 hour dive above 100 ft (keep in mind that O2 consumption has nothing to do with depth). But you must have plenty of left-over dil, because you never know when you might unexpectedly need more than usual. So I am thinking that I can dive the O2 right down to 200-300 psi, but should never let the dil get below 500 psi. What does everyone think of these as just rough ideas?

I may be wrong but I don't think Jeff would suggest that you dive your O2 down to 200-300 psi and or dil down to 500 psi becuase you want to do a couple reped dives without refilling your tanks.

I would suggest spending a couple $$ and getting a second set of dil and o2 tanks.

Just my 2 cents.

BillGraham · 30th September 2007, 21:28

I've been using the 6/12 sodasorb.

For dives to 100-250 feet, in cold water (45-55 f) with 10/50 diluent, I do two dives of 100-120 minutes and then dump the scrubber. I think the Prism recommendation is 4 hours for cold water/helium and 6 for warm water/air diluent. I'm told that it's actually good for much longer, but I just pack a new one.

I don't think I've ever used more than 1000 psi of either in a dive unless there were a lot of depth changes.

For bailout, I bring two tanks sidemount (40's or 80's) and plan for the worst case scenario, having to bail off the machine at the end of the dive.

3rd August 2007, 23:07	#21 (permalink)
*jradomski* Moderator Current Rebreather/s: Inspiration Classic Sport Kiss Optima rEvo Other CCR Home Build Other Rebreather/s: Inspiration Vision Evolution Megalodon Classic Kiss rEvo Other CCR Home Build Join Date: Mar 2005 Location: "Da" Bronx Posts: 2,817	Re: How many hours from a Prism with 19 cft tanks? Quote: (Originally Posted by warjarrett) I think I need to specify more assumptions. The 19s will be full to their maximum rated capacity (not short-filled), I will have no bail-out bottle (so I need to surface with an emergency contigent reserve), and my drysuit and buoyancy bladder have no separate supply (just use gas from the diluent tank). Then, the next question will be, well, how much more time will I get if I do bring a separate bailout bottle? Don't ever dive a Rebreather without bailout its just asking for trouble.. Onboard gas is not bailout, It is acceptable for an intermediate gas while you get onto your bailout gas.... I ALWAYS carry at a minimum of an al 40 for bailout (for recreational depths a 30 would do, but a 40 sits much nicer on my body because its a longer cylinder..) __________________ Joe Radomski CCR Trimix Instructor Trainer ANDI Instructor Trainer Director #10 All posts are personal opinions and DO NOT reflect any affiliated agency unless specifically stated.
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19th August 2007, 22:53	#22 (permalink)
warjarrett New Member Current Rebreather/s: Prism Topaz Sport Kiss Other Rebreather/s: Inspiration Classic Megalodon Join Date: May 2007 Location: Los Angeles Posts: 51	Re: How many hours from a Prism with 19 cft tanks? Here I am again, now responding to my own thread. I just finished a week of training with Jeff Bozanic. And, one thing I learned was that I will ALWAYS carry a bail-out bottle. For a dive to 90-100 ft, the size of the bail-out MUST BE at least 19 cu.ft., to allow for some time to get oriented (if an emergency occurs), a normal ascent, and a 3 minute safety stop. So, now I change my assumptions, but the question still stands >>> Assuming I can fully use-up a pair of 19 cu.ft. cylinders, how many dive-hours can I roughly expect to get from a single pair? I must add these conditions also: no heavy work-load and average physical condition. <<< Ok, my current best answer is this: The latest rule-of-thumb I read is about 500 psi of each (O2 and dill) for an average 1 1/2 hour dive above 100 ft (keep in mind that O2 consumption has nothing to do with depth). But you must have plenty of left-over dil, because you never know when you might unexpectedly need more than usual. So I am thinking that I can dive the O2 right down to 200-300 psi, but should never let the dil get below 500 psi. What does everyone think of these as just rough ideas?
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19th August 2007, 23:01	#23 (permalink)
warjarrett New Member Current Rebreather/s: Prism Topaz Sport Kiss Other Rebreather/s: Inspiration Classic Megalodon Join Date: May 2007 Location: Los Angeles Posts: 51	Re: How many hours from a Prism with 19 cft tanks? Oh, one more thing. Jeff Bozanic DOES NOT recommend diving with a 19 cu. ft. bail-out bottle under any circumstances. This was MY idea, based on what I learned during the theory portion of his lectures. So, NOBODY should take my word for it about this size bail-out. BIGGER IS BETTER...um, I mean... BIGGER IS SAFER.
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19th August 2007, 23:21	#24 (permalink)
dive2dive2000 PRISM DIVER & LUVIN IT! Current Rebreather/s: Prism Topaz Other Rebreather/s: Join Date: Feb 2005 Location: Long Island, NY Posts: 784	Re: How many hours from a Prism with 19 cft tanks? Quote: (Originally Posted by warjarrett) Here I am again, now responding to my own thread. I just finished a week of training with Jeff Bozanic. And, one thing I learned was that I will ALWAYS carry a bail-out bottle. For a dive to 90-100 ft, the size of the bail-out MUST BE at least 19 cu.ft., to allow for some time to get oriented (if an emergency occurs), a normal ascent, and a 3 minute safety stop. So, now I change my assumptions, but the question still stands >>> Assuming I can fully use-up a pair of 19 cu.ft. cylinders, how many dive-hours can I roughly expect to get from a single pair? I must add these conditions also: no heavy work-load and average physical condition. <<< Ok, my current best answer is this: The latest rule-of-thumb I read is about 500 psi of each (O2 and dill) for an average 1 1/2 hour dive above 100 ft (keep in mind that O2 consumption has nothing to do with depth). But you must have plenty of left-over dil, because you never know when you might unexpectedly need more than usual. So I am thinking that I can dive the O2 right down to 200-300 psi, but should never let the dil get below 500 psi. What does everyone think of these as just rough ideas? I have the ability to use off board plug in, but lets not go there.For just starting out I would always try and fill my dil bottle. As the hrs progress and you learn your rig then you will know what is correct and what is not. As far as O2 I think you are cutting it way close. I would never jump in with O2 psi under 1000, unless I had the ability for off board plug in (which I do). Just fill your bottles often dive and learn your kit everything else will fall into place. i __________________ Safe Diving, Martin "but what's the fun of getting what you need, instead of what you want?"
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20th August 2007, 11:02	#25 (permalink)
DaveC New Member Current Rebreather/s: Sport Kiss Classic Kiss Other Rebreather/s: Prism Topaz Join Date: Mar 2005 Location: Ontario. Canada Posts: 192	Re: How many hours from a Prism with 19 cft tanks? Quote: (Originally Posted by dive2dive2000) As far as O2 I think you are cutting it way close. I would never jump in with O2 psi under 1000, unless I had the ability for off board plug in (which I do). Just fill your bottles often dive and learn your kit everything else will fall into place. I think common sense comes into play here. What Setpoint, what depth, duration, etc... Just have to watch the pressure more closely when starting a dive with this kind of volume. __________________ Dave Any day in the water is better then any day in the office.
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9th September 2007, 22:44	#26 (permalink)
warjarrett New Member Current Rebreather/s: Prism Topaz Sport Kiss Other Rebreather/s: Inspiration Classic Megalodon Join Date: May 2007 Location: Los Angeles Posts: 51	Re: How many hours from a Prism with 19 cft tanks? I just finished my first dive after training, and here is what I came up with. I dove a set point of 1.0, but manually kept PO2 between 1.0 and 1.2 (mostly 1.2). Max depth was 80 feet, and duration was 45 minutes. I was diving with OC divers, so we went up and down quite a bit (exhaling through my nose every ascent and using more dil every descent - good practice), and had to end the dive based on their air consumption. I was VERY tired after just this one dive... beginners discomfort I guess, and chose not to do a second. I did carry a 19 cuft bailout, went on it once just for practice. I used about 500 psi O2 and 1000 psi Dil, from 19s (3000 psi fills). I hope this consumption will go down as I get more dives in. At this rate of dil usage, I can only get 2 dives out of a dil tank fill -- there is no air compressor aboard the boat I dive.
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10th September 2007, 00:02	#27 (permalink)
Dsix36 Going Down? Current Rebreather/s: Optima Other Rebreather/s: Join Date: Aug 2007 Location: Deerfield Beach, Florida Posts: 891	Re: How many hours from a Prism with 19 cft tanks? Quote: (Originally Posted by warjarrett) I just finished my first dive after training, and here is what I came up with. I dove a set point of 1.0, but manually kept PO2 between 1.0 and 1.2 (mostly 1.2). Max depth was 80 feet, and duration was 45 minutes. I was diving with OC divers, so we went up and down quite a bit (exhaling through my nose every ascent and using more dil every descent - good practice), and had to end the dive based on their air consumption. I was VERY tired after just this one dive... beginners discomfort I guess, and chose not to do a second. I did carry a 19 cuft bailout, went on it once just for practice. I used about 500 psi O2 and 1000 psi Dil, from 19s (3000 psi fills). I hope this consumption will go down as I get more dives in. At this rate of dil usage, I can only get 2 dives out of a dil tank fill -- there is no air compressor aboard the boat I dive. I don't dive a Prisim, but my consumptions were a lot like yours when I first certified. I only have about 8 dives more than you do. Today I did 4 dives with a total bottom time of 3 hour and 55 minutes. I used 1000psi of Oxy and 900psi of Dil. I use Al20's and the dives were 60-80 ft deep. Your consumption will get better too. __________________ THE MORE THAT I LEARN, THE MORE THAT I STILL NEED TO LEARN!!!!!!
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10th September 2007, 00:06	#28 (permalink)
*diverklondike* Moderator Current Rebreather/s: Inspiration Classic Other CCR Other Rebreather/s: Inspiration Classic Other CCR Join Date: Oct 2005 Location: Delaware, USA Posts: 1,462	Re: How many hours from a Prism with 19 cft tanks? Quote: (Originally Posted by warjarrett) Here I am again, now responding to my own thread. I just finished a week of training with Jeff Bozanic. And, one thing I learned was that I will ALWAYS carry a bail-out bottle. For a dive to 90-100 ft, the size of the bail-out MUST BE at least 19 cu.ft., to allow for some time to get oriented (if an emergency occurs), a normal ascent, and a 3 minute safety stop. So, now I change my assumptions, but the question still stands >>> Assuming I can fully use-up a pair of 19 cu.ft. cylinders, how many dive-hours can I roughly expect to get from a single pair? I must add these conditions also: no heavy work-load and average physical condition. <<< Ok, my current best answer is this: The latest rule-of-thumb I read is about 500 psi of each (O2 and dill) for an average 1 1/2 hour dive above 100 ft (keep in mind that O2 consumption has nothing to do with depth). But you must have plenty of left-over dil, because you never know when you might unexpectedly need more than usual. So I am thinking that I can dive the O2 right down to 200-300 psi, but should never let the dil get below 500 psi. What does everyone think of these as just rough ideas? I may be wrong but I don't think Jeff would suggest that you dive your O2 down to 200-300 psi and or dil down to 500 psi becuase you want to do a couple reped dives without refilling your tanks. I would suggest spending a couple $$ and getting a second set of dil and o2 tanks. Just my 2 cents.
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30th September 2007, 21:28	#29 (permalink)
BillGraham New Member Current Rebreather/s: Prism Topaz Other Rebreather/s: Join Date: Aug 2006 Location: Long Island, New York Posts: 20	Re: How many hours from a Prism with 19 cft tanks? I've been using the 6/12 sodasorb. For dives to 100-250 feet, in cold water (45-55 f) with 10/50 diluent, I do two dives of 100-120 minutes and then dump the scrubber. I think the Prism recommendation is 4 hours for cold water/helium and 6 for warm water/air diluent. I'm told that it's actually good for much longer, but I just pack a new one. I don't think I've ever used more than 1000 psi of either in a dive unless there were a lot of depth changes. For bailout, I bring two tanks sidemount (40's or 80's) and plan for the worst case scenario, having to bail off the machine at the end of the dive. __________________ Avatar photo by Joseff Koppleman (c) HTML Code: www.holeinthewallhouse.com Last edited by BillGraham : 30th September 2007 at 21:39.
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