RB80 Math ?

se2schul · 13th May 2008, 17:04

Can anyone help me out with the algorithm used to calculate the loop stabilization on the RB80?

I'm also interested in how to calculate when the loop will go hypoxic during a depth change.

I am trained on the RB80, and I'm aware of the "rules" to follow to avoid hypoxia while diving the unit.
I'm also aware of a battlefield calculation to calculate at approximately what depth a gas becomes hypoxic.
I also have some simulation software that is supposed to calculate these things for me, however, the software is half German - half English, the interface is a bit "clunky", and I'm not always sure what it's doing. I'm not sure if there's a newer version of this software available.

Anyway, if anyone can help me with the loop stabilization algorithm, and the hypoxia algorithm, it would be much appreciated.

vlada · 13th May 2008, 17:20

There is a formula in "Mastering rebreathers" which i think describes what you are after. There are some constants in there that you'll have to figure out related to loop volume, lung volume and metabolism.

What i saw coming out of that formula when i played with it for a while convinced me that someone with smaller than average lung capacity and higher than average metabolism may have FO2 drops way outside prescribed % that you got in the RB80 class presentaiton.

I just lent the book to a friend, so do not have access, but it was closer to the front, probably under SCR chapter.

Quote: (Originally Posted by se2schul)

Can anyone help me out with the algorithm used to calculate the loop stabilization on the RB80?

I'm also interested in how to calculate when the loop will go hypoxic during a depth change.

I am trained on the RB80, and I'm aware of the "rules" to follow to avoid hypoxia while diving the unit.
I'm also aware of a battlefield calculation to calculate at approximately what depth a gas becomes hypoxic.
I also have some simulation software that is supposed to calculate these things for me, however, the software is half German - half English, the interface is a bit "clunky", and I'm not always sure what it's doing. I'm not sure if there's a newer version of this software available.

Anyway, if anyone can help me with the loop stabilization algorithm, and the hypoxia algorithm, it would be much appreciated.

jaap · 13th May 2008, 18:06

Quote: (Originally Posted by se2schul)

Can anyone help me out with the algorithm used to calculate the loop stabilization on the RB80?

I'm also interested in how to calculate when the loop will go hypoxic during a depth change.

I am trained on the RB80, and I'm aware of the "rules" to follow to avoid hypoxia while diving the unit.
I'm also aware of a battlefield calculation to calculate at approximately what depth a gas becomes hypoxic.
I also have some simulation software that is supposed to calculate these things for me, however, the software is half German - half English, the interface is a bit "clunky", and I'm not always sure what it's doing. I'm not sure if there's a newer version of this software available.

Anyway, if anyone can help me with the loop stabilization algorithm, and the hypoxia algorithm, it would be much appreciated.

Hi

Have you studied this page:
Le Spirotechnique DC55

Since I got an old HAL-fridge collecting dust (yes I know its a different thing with the variable dumpratio) I did an Excel sheet some years ago that calculates the steady state loop fractions for a given feedgas, depth, dumpratio and extraction ratio. Its partially in Swedish and is based on the equations decribed on Åkes "Teknosofen" Larssons homepage. I make no claim that it is correct but you can have it if you want. But I guess that sort of stuff should have been covered in you RB80 training?

But your after time constants too right? Like in this link (but for PSCR and not CMF-SCR):
Åkes’ Constant Massflow Rebreather Technical Page

If you want to look at the time to reach steady state after a sudden movement between two steady state levels it should be quite straight forward to simulate on a PSCR too using the equations from "Teknosofen".
I really should get back to working so I hope I don't start looking at describing that one...

graham_hk · 13th May 2008, 23:16

Quote: (Originally Posted by se2schul)

Can anyone help me out with the algorithm used to calculate the loop stabilization on the RB80?

I'm also interested in how to calculate when the loop will go hypoxic during a depth change.

I am trained on the RB80, and I'm aware of the "rules" to follow to avoid hypoxia while diving the unit.
I'm also aware of a battlefield calculation to calculate at approximately what depth a gas becomes hypoxic.
I also have some simulation software that is supposed to calculate these things for me, however, the software is half German - half English, the interface is a bit "clunky", and I'm not always sure what it's doing. I'm not sure if there's a newer version of this software available.

Anyway, if anyone can help me with the loop stabilization algorithm, and the hypoxia algorithm, it would be much appreciated.

Steve,

The formula is not much use without knowing what to put in it. You will need to measure: what is your Rebreather RMV, what is the real dump ratio (any venting you might do) and how much oxygen do you metabolise.

With those figures I was able to validate the software to predict what happening with loop PO2. My swing was alot more severe than default values.

Graham

Shawn · 13th May 2008, 23:36

Hello,

The RB80 was designed to use DIR standard mixes and nothing more. If you are using these mixes then you know the MOD for each mix. The RB80 is more of a gas extender than a rebreather, so using something other than the standard DIR gas set could be very dangerous.

A typical profile would be to have your bottom gas in your mounted tanks (18/45 up to 190').

You would be on OC to deeper than 20', then youo would begin to breath your loop until it was time to deco.

during deco you plug in your deco gas (standard mixes) at the apropriate depths.

I'm not an RB80 instructor, so the best advise here would be to talk to one
directly. If your using a clone you may be out of luck, if it is an RB80 I know an instructor who MIGHT help. ( big might ) Training is everything to these guys, and if your not properly trained getting help could be next to impossible.

**wedivebc** · 13th May 2008, 23:59

Quote: (Originally Posted by Shawn)

Hello,

The RB80 was designed to use DIR standard mixes and nothing more. If you are using these mixes then you know the MOD for each mix. The RB80 is more of a gas extender than a rebreather, so using something other than the standard DIR gas set could be very dangerous.

A typical profile would be to have your bottom gas in your mounted tanks (18/45 up to 190').

You would be on OC to deeper than 20', then youo would begin to breath your loop until it was time to deco.

during deco you plug in your deco gas (standard mixes) at the apropriate depths.

I'm not an RB80 instructor, so the best advise here would be to talk to one
directly. If your using a clone you may be out of luck, if it is an RB80 I know an instructor who MIGHT help. ( big might ) Training is everything to these guys, and if your not properly trained getting help could be next to impossible.

Did you actually read the OPs post?

graham_hk · 14th May 2008, 03:40

Quote: (Originally Posted by Shawn)

Hello,

The RB80 was designed to use DIR standard mixes and nothing more. If you are using these mixes then you know the MOD for each mix. The RB80 is more of a gas extender than a rebreather, so using something other than the standard DIR gas set could be very dangerous.

A typical profile would be to have your bottom gas in your mounted tanks (18/45 up to 190').

You would be on OC to deeper than 20', then youo would begin to breath your loop until it was time to deco.

during deco you plug in your deco gas (standard mixes) at the apropriate depths.

I'm not an RB80 instructor, so the best advise here would be to talk to one
directly. If your using a clone you may be out of luck, if it is an RB80 I know an instructor who MIGHT help. ( big might ) Training is everything to these guys, and if your not properly trained getting help could be next to impossible.

Why does it matter what gases you use? Not understanding any gas (even standard gases) is going to be give you problems. For example, breathing 18% at 20ft (6m) on an Rb80 is asking for trouble.

Drmike · 14th May 2008, 03:53

Quote: (Originally Posted by Shawn)

The RB80 was designed to use DIR standard mixes and nothing more.

uhuh,

cool aid anyone?

***EBT*** · 14th May 2008, 08:19

Quote: (Originally Posted by graham_hk)

Why does it matter what gases you use? Not understanding any gas (even standard gases) is going to be give you problems. For example, breathing 18% at 20ft (6m) on an Rb80 is asking for trouble.

You've obviously not heard of the speedo valve fitted in the indoctrination port Graham, any non DIR mixes will instantly cause the loop to cease working

rbernabe · 14th May 2008, 09:40

This might help.

SCR-Calculations

I have an excel file for the computation. PM me if you want the file.

Robin

13th May 2008, 17:04	#1 (permalink)
se2schul New Member Current Rebreather/s: RB80 / Clone Other Rebreather/s: RB80 / Clone Join Date: Oct 2007 Location: Ottawa Posts: 65	RB80 Math ? Can anyone help me out with the algorithm used to calculate the loop stabilization on the RB80? I'm also interested in how to calculate when the loop will go hypoxic during a depth change. I am trained on the RB80, and I'm aware of the "rules" to follow to avoid hypoxia while diving the unit. I'm also aware of a battlefield calculation to calculate at approximately what depth a gas becomes hypoxic. I also have some simulation software that is supposed to calculate these things for me, however, the software is half German - half English, the interface is a bit "clunky", and I'm not always sure what it's doing. I'm not sure if there's a newer version of this software available. Anyway, if anyone can help me with the loop stabilization algorithm, and the hypoxia algorithm, it would be much appreciated.
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13th May 2008, 17:20	#2 (permalink)
vlada Diver with a camera Current Rebreather/s: Classic Kiss Ouroboros Other Rebreather/s: Join Date: Apr 2005 Location: Toronto Posts: 60	Re: RB80 Math ? There is a formula in "Mastering rebreathers" which i think describes what you are after. There are some constants in there that you'll have to figure out related to loop volume, lung volume and metabolism. What i saw coming out of that formula when i played with it for a while convinced me that someone with smaller than average lung capacity and higher than average metabolism may have FO2 drops way outside prescribed % that you got in the RB80 class presentaiton. I just lent the book to a friend, so do not have access, but it was closer to the front, probably under SCR chapter. Quote: (Originally Posted by se2schul) Can anyone help me out with the algorithm used to calculate the loop stabilization on the RB80? I'm also interested in how to calculate when the loop will go hypoxic during a depth change. I am trained on the RB80, and I'm aware of the "rules" to follow to avoid hypoxia while diving the unit. I'm also aware of a battlefield calculation to calculate at approximately what depth a gas becomes hypoxic. I also have some simulation software that is supposed to calculate these things for me, however, the software is half German - half English, the interface is a bit "clunky", and I'm not always sure what it's doing. I'm not sure if there's a newer version of this software available. Anyway, if anyone can help me with the loop stabilization algorithm, and the hypoxia algorithm, it would be much appreciated. __________________ Vlada www.wrecksandreefs.com
(Online)

13th May 2008, 18:06	#3 (permalink)
jaap Normal people worry me Current Rebreather/s: Classic Kiss Other CCR RB80 / Clone Ray Other SCR Home Build Other Rebreather/s: Other CCR RB80 / Clone Ray Other SCR Home Build Join Date: Jun 2005 Location: Stockholm Sweden Posts: 438	Re: RB80 Math ? Quote: (Originally Posted by se2schul) Can anyone help me out with the algorithm used to calculate the loop stabilization on the RB80? I'm also interested in how to calculate when the loop will go hypoxic during a depth change. I am trained on the RB80, and I'm aware of the "rules" to follow to avoid hypoxia while diving the unit. I'm also aware of a battlefield calculation to calculate at approximately what depth a gas becomes hypoxic. I also have some simulation software that is supposed to calculate these things for me, however, the software is half German - half English, the interface is a bit "clunky", and I'm not always sure what it's doing. I'm not sure if there's a newer version of this software available. Anyway, if anyone can help me with the loop stabilization algorithm, and the hypoxia algorithm, it would be much appreciated. Hi Have you studied this page: Le Spirotechnique DC55 Since I got an old HAL-fridge collecting dust (yes I know its a different thing with the variable dumpratio) I did an Excel sheet some years ago that calculates the steady state loop fractions for a given feedgas, depth, dumpratio and extraction ratio. Its partially in Swedish and is based on the equations decribed on Åkes "Teknosofen" Larssons homepage. I make no claim that it is correct but you can have it if you want. But I guess that sort of stuff should have been covered in you RB80 training? But your after time constants too right? Like in this link (but for PSCR and not CMF-SCR): Åkes’ Constant Massflow Rebreather Technical Page If you want to look at the time to reach steady state after a sudden movement between two steady state levels it should be quite straight forward to simulate on a PSCR too using the equations from "Teknosofen". I really should get back to working so I hope I don't start looking at describing that one... __________________ My initials: JAAP Last edited by jaap : 13th May 2008 at 18:11.
(Offline)

13th May 2008, 23:16	#4 (permalink)
graham_hk New Member Current Rebreather/s: RB80 / Clone Other Rebreather/s: Inspiration Classic Classic Kiss MK 15.X RB80 / Clone Join Date: Nov 2005 Location: Philippines Posts: 78	Re: RB80 Math ? Quote: (Originally Posted by se2schul) Can anyone help me out with the algorithm used to calculate the loop stabilization on the RB80? I'm also interested in how to calculate when the loop will go hypoxic during a depth change. I am trained on the RB80, and I'm aware of the "rules" to follow to avoid hypoxia while diving the unit. I'm also aware of a battlefield calculation to calculate at approximately what depth a gas becomes hypoxic. I also have some simulation software that is supposed to calculate these things for me, however, the software is half German - half English, the interface is a bit "clunky", and I'm not always sure what it's doing. I'm not sure if there's a newer version of this software available. Anyway, if anyone can help me with the loop stabilization algorithm, and the hypoxia algorithm, it would be much appreciated. Steve, The formula is not much use without knowing what to put in it. You will need to measure: what is your Rebreather RMV, what is the real dump ratio (any venting you might do) and how much oxygen do you metabolise. With those figures I was able to validate the software to predict what happening with loop PO2. My swing was alot more severe than default values. Graham
(Online)

13th May 2008, 23:36	#5 (permalink)
Shawn Custom Title Allowed! Current Rebreather/s: Megalodon Other CCR RB80 / Clone Other Rebreather/s: Other CCR RB80 / Clone Join Date: Oct 2007 Location: Kansas City Kansas Posts: 106	Re: RB80 Math ? Hello, The RB80 was designed to use DIR standard mixes and nothing more. If you are using these mixes then you know the MOD for each mix. The RB80 is more of a gas extender than a rebreather, so using something other than the standard DIR gas set could be very dangerous. A typical profile would be to have your bottom gas in your mounted tanks (18/45 up to 190'). You would be on OC to deeper than 20', then youo would begin to breath your loop until it was time to deco. during deco you plug in your deco gas (standard mixes) at the apropriate depths. I'm not an RB80 instructor, so the best advise here would be to talk to one directly. If your using a clone you may be out of luck, if it is an RB80 I know an instructor who MIGHT help. ( big might ) Training is everything to these guys, and if your not properly trained getting help could be next to impossible. __________________ WWW.DiveOne.net
(Offline)

13th May 2008, 23:59	#6 (permalink)
wedivebc FIGJAM Current Rebreather/s: Megalodon Other CCR Other Rebreather/s: Not Bought Yet Inspiration Classic Sport Kiss Other CCR Join Date: Feb 2005 Location: Vancouver Island BC Canada Posts: 1,358	Re: RB80 Math ? Quote: (Originally Posted by Shawn) Hello, The RB80 was designed to use DIR standard mixes and nothing more. If you are using these mixes then you know the MOD for each mix. The RB80 is more of a gas extender than a rebreather, so using something other than the standard DIR gas set could be very dangerous. A typical profile would be to have your bottom gas in your mounted tanks (18/45 up to 190'). You would be on OC to deeper than 20', then youo would begin to breath your loop until it was time to deco. during deco you plug in your deco gas (standard mixes) at the apropriate depths. I'm not an RB80 instructor, so the best advise here would be to talk to one directly. If your using a clone you may be out of luck, if it is an RB80 I know an instructor who MIGHT help. ( big might ) Training is everything to these guys, and if your not properly trained getting help could be next to impossible. Did you actually read the OPs post? __________________ Cheers, Dave.... Man is the only animal burdened with the knowledge he will eventually die
(Offline)

14th May 2008, 03:40	#7 (permalink)
graham_hk New Member Current Rebreather/s: RB80 / Clone Other Rebreather/s: Inspiration Classic Classic Kiss MK 15.X RB80 / Clone Join Date: Nov 2005 Location: Philippines Posts: 78	Re: RB80 Math ? Quote: (Originally Posted by Shawn) Hello, The RB80 was designed to use DIR standard mixes and nothing more. If you are using these mixes then you know the MOD for each mix. The RB80 is more of a gas extender than a rebreather, so using something other than the standard DIR gas set could be very dangerous. A typical profile would be to have your bottom gas in your mounted tanks (18/45 up to 190'). You would be on OC to deeper than 20', then youo would begin to breath your loop until it was time to deco. during deco you plug in your deco gas (standard mixes) at the apropriate depths. I'm not an RB80 instructor, so the best advise here would be to talk to one directly. If your using a clone you may be out of luck, if it is an RB80 I know an instructor who MIGHT help. ( big might ) Training is everything to these guys, and if your not properly trained getting help could be next to impossible. Why does it matter what gases you use? Not understanding any gas (even standard gases) is going to be give you problems. For example, breathing 18% at 20ft (6m) on an Rb80 is asking for trouble.
(Online)

14th May 2008, 03:53	#8 (permalink)
Drmike Custom Title Allowed! Current Rebreather/s: MK 15.X Ouroboros Other CCR Home Build Other Rebreather/s: Inspiration Classic Other CCR Home Build Join Date: Feb 2005 Posts: 3,128	Re: RB80 Math ? Quote: (Originally Posted by Shawn) The RB80 was designed to use DIR standard mixes and nothing more. uhuh, cool aid anyone? __________________ Get a girlfriend you sad twat - a Rebreather is an unfaithful mistress - dont blind yourself to her faults just because she goes down on you
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14th May 2008, 08:19	#9 (permalink)
*EBT* Apprentice Luddite Current Rebreather/s: Classic Kiss Other Rebreather/s: Inspiration Classic Join Date: Feb 2005 Location: UK, Brighton Posts: 1,855	Re: RB80 Math ? Quote: (Originally Posted by graham_hk) Why does it matter what gases you use? Not understanding any gas (even standard gases) is going to be give you problems. For example, breathing 18% at 20ft (6m) on an Rb80 is asking for trouble. You've obviously not heard of the speedo valve fitted in the indoctrination port Graham, any non DIR mixes will instantly cause the loop to cease working __________________ Eagles May Soar, but weasels don't get sucked into jet engines! Rebreather World Terms of service Real diving t-shirts for real divers
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14th May 2008, 09:40	#10 (permalink)
rbernabe New Member Current Rebreather/s: RB80 / Clone Dolphin Other Rebreather/s: RB80 / Clone Dolphin Join Date: Mar 2007 Location: Philippines Posts: 4	Re: RB80 Math ? This might help. SCR-Calculations I have an excel file for the computation. PM me if you want the file. Robin
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