Scrubber design idea

spacemanspiff1974 · 14th April 2006, 19:09

I have an idea for a scrubber design, but need somebody to tell me why this is a bad idea so that I can consider all angles.

Radial scrubber encased in an outer canister - think prism for example.

The scrubber canister is made from a large steel food can - the economy size at the bottom shelf of the canned veg. section of the grocery store - approx 6" diameter and 7" height.

I would cut out most of the side area to allow for air passage, leaving just enough metal left to maintain structural integrity (think of a cylindrical cage with only vertical bars (or also including a single horizontal bar if necessary) - kind of like the prism scrubber.

I would then attach 316 stainless mesh to cover the openings and prevent the scrubber material from spilling out.

The center of the scrubber would have a 1.25" diameter 316 or hdpe pipe drilled with enough holes to allow passage of air into the scrubber yet not enough to danger the structural integrity of the pipe.

The top of the scrubber canister would be a metal disc with a hole just big enoug for the 1.25" diameter pipe and would be held in place.

See attached pdf.

Does anyone see something wrong with this concept? I believe that food grade steel cans are coated in tin, which should not be reactive.

Sutty · 14th April 2006, 19:40

It would rust a lot. I don't know whether there is any reaction between tin and soda-lime (or if there is whether the tin compounds would be toxic). However where sections are cut-out you will expose the steel under the tin and in a wet high O2 environment I'd expect it to rust like crazy!
How about plastic - probably good reasons most people use it!

spacemanspiff1974 · 14th April 2006, 20:23

From my chemistry classes and the internet, I dont recall tin being too reactive with calcium hydroxide. I believe the reactivity was near that of steel.

Good point on the rust issue. I suppose that is why they coat the steel in tin to begin with. I guess making food cans in 316 would be a bit pricey.

I'm also considering hdpe and ceramic composite for the application. Was considering 316 ss, but that stuff gets expensive when you start talking 6" diameter.

Gecko · 15th April 2006, 00:36

I think you should double check your food can idea. They are generally tin coated steel cans, not pure tin and the tin often wears off.

The calcium hydroxide does produce acid when in contact with moisture (water), which in turn may react with the metal. I'm not a chemist but I suggest you do a more thorough investigation on calcium hydroxide reactive byproducts if you are going to make a metal cannister.

Let us see the photos when you're done!!

cheers

jaap · 15th April 2006, 01:15

Quote: (Originally Posted by Gecko)

I think you should double check your food can idea. They are generally tin coated steel cans, not pure tin and the tin often wears off.

The calcium hydroxide does produce acid when in contact with moisture (water), which in turn may react with the metal. I'm not a chemist but I suggest you do a more thorough investigation on calcium hydroxide reactive byproducts if you are going to make a metal cannister.

Let us see the photos when you're done!!

cheers

Well the sorb is the opposite of acid, its a strong base (mainly from the NaOH/KOH in it). But its very corrosive anyway.

Spaceman, about the "can"-scrubber. Don't spend to much time and money on it. There is a good chance it will not hold very long or that you will get tired of it and buy/make something else.

If I would build it I would go for plastic. But then again its easier and quite cheap to just buy a scrubber designed for UW-use (like from IDA-Rebreather's).

If you do decide to build it, it could be possible to rustproof the "can"-parts.
I and some friends have some rusty old O2-Rebreather and one guy polished and painted the corroded scrubber with something that made it look like it was galvanized.

DepthCharge · 15th April 2006, 12:12

Quote: (Originally Posted by spacemanspiff1974)

I have an idea for a scrubber design, but need somebody to tell me why this is a bad idea so that I can consider all angles.

Radial scrubber encased in an outer canister - think prism for example.

The scrubber canister is made from a large steel food can - the economy size at the bottom shelf of the canned veg. section of the grocery store - approx 6" diameter and 7" height.

I would cut out most of the side area to allow for air passage, leaving just enough metal left to maintain structural integrity (think of a cylindrical cage with only vertical bars (or also including a single horizontal bar if necessary) - kind of like the prism scrubber.

I would then attach 316 stainless mesh to cover the openings and prevent the scrubber material from spilling out.

The center of the scrubber would have a 1.25" diameter 316 or hdpe pipe drilled with enough holes to allow passage of air into the scrubber yet not enough to danger the structural integrity of the pipe.

The top of the scrubber canister would be a metal disc with a hole just big enoug for the 1.25" diameter pipe and would be held in place.

See attached pdf.

Does anyone see something wrong with this concept? I believe that food grade steel cans are coated in tin, which should not be reactive.

I have some 316l stainless tubes, 5.825" O.D. X 24 Ga. X approx 12" Long with 033" Diameter Round Holes, on .077" Staggered Centers. This gives about 20% open pace (wont effect WOB). I plan on sticking them in canisters 6.5" - 7" I.D. (depending on what I can find). For the inner tube (again depending on what I can locate easy) I'll use either a SS or maybe HDPE tube ( SS would work better). On these I'll cut thin slits staggared around the tube. Should also not effect WOB as will have a large open space.

Skipbreather · 15th April 2006, 15:33

Quote: (Originally Posted by DepthCharge)

For the inner tube (again depending on what I can locate easy) I'll use either a SS or maybe HDPE tube ( SS would work better). On these I'll cut thin slits staggared around the tube. Should also not effect WOB as will have a large open space.

You just might find this little gem useful. It is part #LS140 from Banjo Corp. in Illinois. A thorough Google will turn up a few on line dealers. It is the center filter element for a chemical strainer intended for spraying agricultural chemicals. It is fiberglass filled injection molded plastic, 304 stainless screen, available in both 40 and 80 mesh (I use the 40 mesh). 5 ¼ inches long. 1 ¼ inches ID. Cost under $10.

Ken

DepthCharge · 15th April 2006, 15:59

Quote: (Originally Posted by Skipbreather)

You just might find this little gem useful. It is part #LS140 from Banjo Corp. in Illinois. A thorough Google will turn up a few on line dealers. It is the center filter element for a chemical strainer intended for spraying agricultural chemicals. It is fiberglass filled injection molded plastic, 304 stainless screen, available in both 40 and 80 mesh (I use the 40 mesh). 5 ¼ inches long. 1 ¼ inches ID. Cost under $10.

Ken

Looks good! Thanks for the info, will check them out.

E-man · 15th April 2006, 20:10

You also want your scubber warm and metal is a good conductor of heat into the ambiet water...another reason to throw a vote to plastics

Joseph Grech · 16th April 2006, 11:28

Azimuth scrubber is very similar in design. It is all made of 316 stainless steel with no issue to condensation inside.

14th April 2006, 19:40	#2 (permalink)
Sutty Classic Kiss diver Current Rebreather/s: Classic Kiss Other Rebreather/s: Join Date: Jun 2005 Location: Glossop, Derbyshire, UK Posts: 837	Re: Scrubber design idea It would rust a lot. I don't know whether there is any reaction between tin and soda-lime (or if there is whether the tin compounds would be toxic). However where sections are cut-out you will expose the steel under the tin and in a wet high O2 environment I'd expect it to rust like crazy! How about plastic - probably good reasons most people use it! __________________ Never forget that life is a finite resource. Last edited by Sutty : 14th April 2006 at 19:41. Reason: spelling
(Offline)

14th April 2006, 20:23	#3 (permalink)
spacemanspiff1974 New Member Current Rebreather/s: Not Bought Yet Other Rebreather/s: Not Bought Yet Join Date: Mar 2006 Location: Houston Posts: 13	Re: Scrubber design idea From my chemistry classes and the internet, I dont recall tin being too reactive with calcium hydroxide. I believe the reactivity was near that of steel. Good point on the rust issue. I suppose that is why they coat the steel in tin to begin with. I guess making food cans in 316 would be a bit pricey. I'm also considering hdpe and ceramic composite for the application. Was considering 316 ss, but that stuff gets expensive when you start talking 6" diameter.
(Offline)

15th April 2006, 00:36	#4 (permalink)
Gecko New Member Current Rebreather/s: Not Bought Yet Other Rebreather/s: Not Bought Yet Join Date: Apr 2006 Posts: 4	Re: Scrubber design idea I think you should double check your food can idea. They are generally tin coated steel cans, not pure tin and the tin often wears off. The calcium hydroxide does produce acid when in contact with moisture (water), which in turn may react with the metal. I'm not a chemist but I suggest you do a more thorough investigation on calcium hydroxide reactive byproducts if you are going to make a metal cannister. Let us see the photos when you're done!! cheers
(Offline)

15th April 2006, 01:15	#5 (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: 473	Re: Scrubber design idea Quote: (Originally Posted by Gecko) I think you should double check your food can idea. They are generally tin coated steel cans, not pure tin and the tin often wears off. The calcium hydroxide does produce acid when in contact with moisture (water), which in turn may react with the metal. I'm not a chemist but I suggest you do a more thorough investigation on calcium hydroxide reactive byproducts if you are going to make a metal cannister. Let us see the photos when you're done!! cheers Well the sorb is the opposite of acid, its a strong base (mainly from the NaOH/KOH in it). But its very corrosive anyway. Spaceman, about the "can"-scrubber. Don't spend to much time and money on it. There is a good chance it will not hold very long or that you will get tired of it and buy/make something else. If I would build it I would go for plastic. But then again its easier and quite cheap to just buy a scrubber designed for UW-use (like from IDA-Rebreather's). If you do decide to build it, it could be possible to rustproof the "can"-parts. I and some friends have some rusty old O2-Rebreather and one guy polished and painted the corroded scrubber with something that made it look like it was galvanized.
(Offline)

15th April 2006, 12:12	#6 (permalink)
DepthCharge New Member Current Rebreather/s: Inspiration Classic Home Build Other Rebreather/s: Home Build Join Date: Mar 2005 Location: upstate NY Posts: 234	Re: Scrubber design idea Quote: (Originally Posted by spacemanspiff1974) I have an idea for a scrubber design, but need somebody to tell me why this is a bad idea so that I can consider all angles. Radial scrubber encased in an outer canister - think prism for example. The scrubber canister is made from a large steel food can - the economy size at the bottom shelf of the canned veg. section of the grocery store - approx 6" diameter and 7" height. I would cut out most of the side area to allow for air passage, leaving just enough metal left to maintain structural integrity (think of a cylindrical cage with only vertical bars (or also including a single horizontal bar if necessary) - kind of like the prism scrubber. I would then attach 316 stainless mesh to cover the openings and prevent the scrubber material from spilling out. The center of the scrubber would have a 1.25" diameter 316 or hdpe pipe drilled with enough holes to allow passage of air into the scrubber yet not enough to danger the structural integrity of the pipe. The top of the scrubber canister would be a metal disc with a hole just big enoug for the 1.25" diameter pipe and would be held in place. See attached pdf. Does anyone see something wrong with this concept? I believe that food grade steel cans are coated in tin, which should not be reactive. I have some 316l stainless tubes, 5.825" O.D. X 24 Ga. X approx 12" Long with 033" Diameter Round Holes, on .077" Staggered Centers. This gives about 20% open pace (wont effect WOB). I plan on sticking them in canisters 6.5" - 7" I.D. (depending on what I can find). For the inner tube (again depending on what I can locate easy) I'll use either a SS or maybe HDPE tube ( SS would work better). On these I'll cut thin slits staggared around the tube. Should also not effect WOB as will have a large open space. __________________ Later, John It's better to beg forgiveness than ask permission
(Offline)

15th April 2006, 15:59	#8 (permalink)
DepthCharge New Member Current Rebreather/s: Inspiration Classic Home Build Other Rebreather/s: Home Build Join Date: Mar 2005 Location: upstate NY Posts: 234	Re: Scrubber design idea Quote: (Originally Posted by Skipbreather) You just might find this little gem useful. It is part #LS140 from Banjo Corp. in Illinois. A thorough Google will turn up a few on line dealers. It is the center filter element for a chemical strainer intended for spraying agricultural chemicals. It is fiberglass filled injection molded plastic, 304 stainless screen, available in both 40 and 80 mesh (I use the 40 mesh). 5 ¼ inches long. 1 ¼ inches ID. Cost under $10. Ken Looks good! Thanks for the info, will check them out. __________________ Later, John It's better to beg forgiveness than ask permission
(Offline)

15th April 2006, 20:10	#9 (permalink)
E-man On the loop! Current Rebreather/s: Inspiration Classic Optima Other Rebreather/s: Titan Join Date: Sep 2005 Location: Eastern Coast ;) Posts: 212	Re: Scrubber design idea You also want your scubber warm and metal is a good conductor of heat into the ambiet water...another reason to throw a vote to plastics
(Offline)

16th April 2006, 11:28	#10 (permalink)
Joseph Grech Joseph Grech Current Rebreather/s: Azimuth Other Rebreather/s: Azimuth Join Date: Mar 2005 Location: Malta Posts: 104	Re: Scrubber design idea Azimuth scrubber is very similar in design. It is all made of 316 stainless steel with no issue to condensation inside.
(Offline)

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