Designing rebreathers that need no tools?

marekm · 18th March 2007, 06:36

What are the pro's and con's of designing a rebreather so that it can be stripped apart without using any tools? Alternatively, is it that big a problem to need a screwdriver and a shifter to pull apart a rebreather that needs tools for disassembly?

What are peoples ideas on the subject?

-Marek

AD_ward9 · 18th March 2007, 08:07

Quote: (Originally Posted by marekm)

What are the pro's and con's of designing a rebreather so that it can be stripped apart without using any tools? Alternatively, is it that big a problem to need a screwdriver and a shifter to pull apart a rebreather that needs tools for disassembly?

What are peoples ideas on the subject?

-Marek

"Stripped apart" - definition needed.

IMHO, all user serviceable parts should not require tools in an ideal world.

IMHO, all non-user serviceable parts should require tools to access.

What is user serviceable and what is not, should be defined clearly by the manufacturer. In my book, the only thing a user should have to do is change out O2 sensors, replace the scrubber and wash the beast.

All very general statements are not true taken to the limit, including this one,.
What that means is we currently require a tool to remove the scrubber. Two cork-screws. It damages the scrubber so it is obvious if an EAC is used or not.

The wind yesterday has stopped, the snow this morning has stopped, Scotland is sunny today, so going diving now ...

Alex

marekm · 18th March 2007, 09:06

By "strip apart", I meant every single part down to the basic parts that are at the factory. So basically the guy at the assembly line in the factory need only use his hands to put the whole rebreather together. Conversely, an enthusiastic diver can disassemble the unit as much as they want to repair it in the field.

It seems most units are a mix and match of parts, some of which need tools (sometimes very specialised tools) while others can be disassembled by hand. I'm curious if anyone considered making a completely tool-less design from top to bottom.

jptaylor9 · 18th March 2007, 09:14

Quote: (Originally Posted by marekm)

It seems most units are a mix and match of parts, some of which need tools (sometimes very specialised tools) while others can be disassembled by hand. I'm curious if anyone considered making a completely tool-less design from top to bottom.

How are you going to fit medium pressure/inflator hoses? Just finger tight? Surely you need some spanners or an adjustable for us non-engineers

Digger · 18th March 2007, 09:28

I want a unit which I can strip down to bare components. In the middle of nowhere when a unit isn't working, you know how to fix it, but you can't remove or change a fitting to keep a trip diving can be extremely frustrating, and lead to bodge tools being used.

There are special tools required for some units. I would rather they weren't special tools, because then you have to carry them in addition to all the other tools you need on a trip. More weight of the baggage allowance.

Keep it user serviceable, and you will keep rebreather divers happy. We have the right to damage and break our unit if we know what we're doing, and at the same time good instructions as to what is and isn't a good idea for the user to do is also required.

Digs.

AD_ward9 · 18th March 2007, 14:02

Quote: (Originally Posted by marekm)

Conversely, an enthusiastic diver can disassemble the unit as much as they want to repair it in the field.
<snip>
I'm curious if anyone considered making a completely tool-less design from top to bottom.

I hope not: that goal would be simply poor design practice.

Do you do that with your first stage regulators?

A better goal is to design out the problems that stop it working in the middle of nowhere.

Alex

marekm · 18th March 2007, 16:00

Quote: (Originally Posted by AD_ward9)

Do you do that with your first stage regulators?
Alex

Yes I do. I strip and clean them twice a year and swap valve seats in the field as required. However, I carry a big bag of tools and parts to make this possible.

But getting back to the point. If pulling a rebreather completely to pieces without tools is a bad design idea, what about making all the critical parts modular, so they can be easily swapped out without tools if they break?

AD_ward9 · 19th March 2007, 05:53

Quote: (Originally Posted by marekm)

But getting back to the point. If pulling a rebreather completely to pieces without tools is a bad design idea, what about making all the critical parts modular, so they can be easily swapped out without tools if they break?

Absolutely. Modular design should be part of every safety system.

Alex

Ben Field · 19th March 2007, 07:33

Have you taken a look at the SportKISS?

It can be disassembled almost completely (okay- not the first stages) by hand, further "occasional" maintenance level of dismantlement can be achieved with a screwdriver (not a specialist tool IMO) I think it almost covers your brief?

FWIW most rebreathers I've seen up close can be strips pretty extensively with very basic tools, screwdrivers, allen keys and spanners.... other than desolding the PCB's and rebuilding first stages how "deep" do you really need to get?

BEN

marekm · 19th March 2007, 08:01

Yes, I've pulled apart a Sport KISS courtesy of the local rebreather shop (thanks D3). However, I noted that the BOV and loop need tools to disassemble or adjust.

The scrubber and heads however, are pretty much tool-less and nicely designed. I considered buying a SK, but my preference for OTS CL's, up-right cylinder valves and R17D/R22D O2 sensors would mean alot of modification to get the rebreather the way I would like it.

18th March 2007, 06:36	#1 (permalink)
marekm Banned Current Rebreather/s: Not Bought Yet Other Rebreather/s: Not Bought Yet Join Date: Oct 2006 Location: Brisbane, Australia Posts: 196	Designing rebreathers that need no tools? What are the pro's and con's of designing a rebreather so that it can be stripped apart without using any tools? Alternatively, is it that big a problem to need a screwdriver and a shifter to pull apart a rebreather that needs tools for disassembly? What are peoples ideas on the subject? -Marek
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18th March 2007, 08:07	#2 (permalink)
AD_ward9 So much more to learn Current Rebreather/s: Other CCR Other Rebreather/s: Other CCR Join Date: Jun 2005 Location: Scotland Posts: 1,854	Re: Designing rebreathers that need no tools? Quote: (Originally Posted by marekm) What are the pro's and con's of designing a rebreather so that it can be stripped apart without using any tools? Alternatively, is it that big a problem to need a screwdriver and a shifter to pull apart a rebreather that needs tools for disassembly? What are peoples ideas on the subject? -Marek "Stripped apart" - definition needed. IMHO, all user serviceable parts should not require tools in an ideal world. IMHO, all non-user serviceable parts should require tools to access. What is user serviceable and what is not, should be defined clearly by the manufacturer. In my book, the only thing a user should have to do is change out O2 sensors, replace the scrubber and wash the beast. All very general statements are not true taken to the limit, including this one,. What that means is we currently require a tool to remove the scrubber. Two cork-screws. It damages the scrubber so it is obvious if an EAC is used or not. The wind yesterday has stopped, the snow this morning has stopped, Scotland is sunny today, so going diving now ... Alex Last edited by AD_ward9 : 18th March 2007 at 08:16.
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18th March 2007, 09:06	#3 (permalink)
marekm Banned Current Rebreather/s: Not Bought Yet Other Rebreather/s: Not Bought Yet Join Date: Oct 2006 Location: Brisbane, Australia Posts: 196	Re: Designing rebreathers that need no tools? By "strip apart", I meant every single part down to the basic parts that are at the factory. So basically the guy at the assembly line in the factory need only use his hands to put the whole rebreather together. Conversely, an enthusiastic diver can disassemble the unit as much as they want to repair it in the field. It seems most units are a mix and match of parts, some of which need tools (sometimes very specialised tools) while others can be disassembled by hand. I'm curious if anyone considered making a completely tool-less design from top to bottom.
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18th March 2007, 09:14	#4 (permalink)
jptaylor9 Member Current Rebreather/s: Inspiration Vision Other Rebreather/s: Inspiration Classic Join Date: Feb 2005 Location: London, UK Posts: 318	Re: Designing rebreathers that need no tools? Quote: (Originally Posted by marekm) It seems most units are a mix and match of parts, some of which need tools (sometimes very specialised tools) while others can be disassembled by hand. I'm curious if anyone considered making a completely tool-less design from top to bottom. How are you going to fit medium pressure/inflator hoses? Just finger tight? Surely you need some spanners or an adjustable for us non-engineers
(Online)

18th March 2007, 09:28	#5 (permalink)
Digger Custom Title Allowed! Current Rebreather/s: Inspiration Classic Other Rebreather/s: Not Bought Yet Inspiration Classic Classic Kiss Join Date: Feb 2005 Location: Midlands UK Posts: 206	Re: Designing rebreathers that need no tools? I want a unit which I can strip down to bare components. In the middle of nowhere when a unit isn't working, you know how to fix it, but you can't remove or change a fitting to keep a trip diving can be extremely frustrating, and lead to bodge tools being used. There are special tools required for some units. I would rather they weren't special tools, because then you have to carry them in addition to all the other tools you need on a trip. More weight of the baggage allowance. Keep it user serviceable, and you will keep rebreather divers happy. We have the right to damage and break our unit if we know what we're doing, and at the same time good instructions as to what is and isn't a good idea for the user to do is also required. Digs.
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18th March 2007, 14:02	#6 (permalink)
AD_ward9 So much more to learn Current Rebreather/s: Other CCR Other Rebreather/s: Other CCR Join Date: Jun 2005 Location: Scotland Posts: 1,854	Re: Designing rebreathers that need no tools? Quote: (Originally Posted by marekm) Conversely, an enthusiastic diver can disassemble the unit as much as they want to repair it in the field. <snip> I'm curious if anyone considered making a completely tool-less design from top to bottom. I hope not: that goal would be simply poor design practice. Do you do that with your first stage regulators? A better goal is to design out the problems that stop it working in the middle of nowhere. Alex
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18th March 2007, 16:00	#7 (permalink)
marekm Banned Current Rebreather/s: Not Bought Yet Other Rebreather/s: Not Bought Yet Join Date: Oct 2006 Location: Brisbane, Australia Posts: 196	Re: Designing rebreathers that need no tools? Quote: (Originally Posted by AD_ward9) Do you do that with your first stage regulators? Alex Yes I do. I strip and clean them twice a year and swap valve seats in the field as required. However, I carry a big bag of tools and parts to make this possible. But getting back to the point. If pulling a rebreather completely to pieces without tools is a bad design idea, what about making all the critical parts modular, so they can be easily swapped out without tools if they break?
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19th March 2007, 05:53	#8 (permalink)
AD_ward9 So much more to learn Current Rebreather/s: Other CCR Other Rebreather/s: Other CCR Join Date: Jun 2005 Location: Scotland Posts: 1,854	Re: Designing rebreathers that need no tools? Quote: (Originally Posted by marekm) But getting back to the point. If pulling a rebreather completely to pieces without tools is a bad design idea, what about making all the critical parts modular, so they can be easily swapped out without tools if they break? Absolutely. Modular design should be part of every safety system. Alex
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19th March 2007, 07:33	#9 (permalink)
Ben Field CK+Shearwater Current Rebreather/s: Classic Kiss Other Rebreather/s: Sport Kiss Join Date: Aug 2005 Location: London, England Posts: 1,632	Re: Designing rebreathers that need no tools? Have you taken a look at the SportKISS? It can be disassembled almost completely (okay- not the first stages) by hand, further "occasional" maintenance level of dismantlement can be achieved with a screwdriver (not a specialist tool IMO) I think it almost covers your brief? FWIW most rebreathers I've seen up close can be strips pretty extensively with very basic tools, screwdrivers, allen keys and spanners.... other than desolding the PCB's and rebuilding first stages how "deep" do you really need to get? BEN __________________ Know your PPO2, Pre-breath, Use checklists, Validate cells at 6mtrs, Use pure O2 at or near surface, Use a BOV, Don't dive Solo, Change Slime and Cells as recommended by Manufacturer and RTFM! Beware Fridge Suck! www.hugsac.org.uk
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19th March 2007, 08:01	#10 (permalink)
marekm Banned Current Rebreather/s: Not Bought Yet Other Rebreather/s: Not Bought Yet Join Date: Oct 2006 Location: Brisbane, Australia Posts: 196	Re: Designing rebreathers that need no tools? Yes, I've pulled apart a Sport KISS courtesy of the local rebreather shop (thanks D3). However, I noted that the BOV and loop need tools to disassemble or adjust. The scrubber and heads however, are pretty much tool-less and nicely designed. I considered buying a SK, but my preference for OTS CL's, up-right cylinder valves and R17D/R22D O2 sensors would mean alot of modification to get the rebreather the way I would like it.
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