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SurfLung
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Condenser Towers vs. Filter Towers

Thu Apr 05, 2018 10:46 am

Condenser Towers vs. Filter Towers
- I think it might be a good topic to compare the types of "towers", how they work, and where to position them in the air line on a scuba compressor.
- For example, my RIX compressor has moisture condensing towers after the 2nd and 3rd stages and they are very different from other moisture towers and TOTALLY different from filter towers. My RIX towers inlet air near the top, it goes through a cyclone twisting section... I suppose to use centrifugal force to settle condensed water downward. Dry air goes up thru the middle of the cyclone apparatus and exits out the top. The drain valves are on the bottom. Air Outlet is at the top.
Separators.jpg
- I have a 4-tube filter array (I think made by Coltri) in which the first tube is a moisture collector. This tube inlets air at the bottom thru a dip tube that extends up about 2/3rds of the way inside the tube. Drain valve is at the bottom. Air Outlet is on top.
- My filter tubes have nothing inside except the filter cartridges. Air inlets on the bottom and outlets on the top.
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antique diver
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Re: Condenser Towers vs. Filter Towers

Thu Apr 05, 2018 9:57 pm

Eben, your filter set came off an Aerosub portable compressor, made by the Italian company, Olmeva. I was using the compressor at home until the 4th stage piston wrecked about 18 years ago. Seems to have been the weak link on those units.

Still have all the other parts in a box, and all are ok except the final piston and cylinder.... just in case anyone needs some Aerosub parts.
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ScubaLawyer
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Re: Condenser Towers vs. Filter Towers

Sun Apr 08, 2018 4:21 am

I'm still on my quest to try to learn all I can about compressors. A friend of a friend got a brand new Alkin W31 and filter system and I was invited over to see him set it up. In addition to the separator(s) and the attached short filter tower that come with the compressor, he also had three 36 inch filter towers affixed to the wall. In each of those towers he had a Lawrence Factor three media filter. He said he needed the extra filters to get "medical grade" air which he uses in his nitrox, helox, trimix and other assorted Voodoo death gases he mixes in his garage. Looked like overkill, but what do I know.

What interested me was that he had the standard back pressure (PMV) valve that came with the compressor which was located just after the first short built in filter tower (that the fill whip usually attaches to), and then he installed a second back pressure valve after the three wall mounted towers.

Is that normal? All the other systems I've seen and really looked at (only a few) just have one back pressure valve at the end of the entire system, post filter array and just before the fill whip.

Again, I'm fairly ignorant here but have all confidence this compressor stuff isn't rocket science. Mark
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hunterkz
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Re: Condenser Towers vs. Filter Towers

Sun Apr 08, 2018 11:27 am

I am also interested in Mark's question. Does the first pmv help get rid of the water before it goes to the filter system? Does it need two or is the one at the end of the line good enough.

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antique diver
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Re: Condenser Towers vs. Filter Towers

Sun Apr 08, 2018 12:45 pm

ScubaLawyer wrote:
Sun Apr 08, 2018 4:21 am
I'm still on my quest to try to learn all I can about compressors. A friend of a friend got a brand new Alkin W31 and filter system and I was invited over to see him set it up. In addition to the separator(s) and the attached short filter tower that come with the compressor, he also had three 36 inch filter towers affixed to the wall. In each of those towers he had a Lawrence Factor three media filter. He said he needed the extra filters to get "medical grade" air which he uses in his nitrox, helox, trimix and other assorted Voodoo death gases he mixes in his garage. Looked like overkill, but what do I know.

What interested me was that he had the standard back pressure (PMV) valve that came with the compressor which was located just after the first short built in filter tower (that the fill whip usually attaches to), and then he installed a second back pressure valve after the three wall mounted towers.

Is that normal? All the other systems I've seen and really looked at (only a few) just have one back pressure valve at the end of the entire system, post filter array and just before the fill whip.

Again, I'm fairly ignorant here but have all confidence this compressor stuff isn't rocket science. Mark
Overkill? Probably. He likely could get O2 compatible air with one tall filter added to his original one, but it would have to be tested to confirm. That's a relatively low volume compressor to run through so many filters, but it sure doesn't hurt anything but his pocketbook. Would still need testing, but less often. Added safety factor is certainly comforting when playing with Oxygen and diving the way he probably does. Three filters on a trailered 15 cfm compressor always gave me amazingly pure air for blending, and the slower air flow of the smaller Alkin compressor makes the filtration even more efficient.

The first back pressure valve was original and he just left it in place. You are right that it is not really required, but it would add to the efficiency of the original first tower since it would reach a higher pressure sooner than if he was filling all four towers. Result of that would be dryer air reaching the subsequent towers sooner, and in my opinion an increase in efficiency. Also, if that Alkin has a floating final piston like some others do, the sooner the pressure on that piston increased the sooner the floating piston would be held firmly against the drive piston, reducing wear and tear and noise. Better for those two pistons, bearings, rods, etc., and conceivably increasing machine life. :)

BTW, you mentioned that compressor stuff is not like Rocket Science, but I do know of a couple of instances where compressor stuff did become "Rocket Science". One when the top cover "launched" from an old Worthington compressor separator, up through my friend's porch awning. It did not reach orbit, but the concussion did blow a nearby kitchen window into the house, and his wife was somewhat displeased. The separator top was found in the yard several houses away, and no one was injured, with the exception of some hearing loss. He called me over to see the damage that same day. In a decision reached in a heated consultation with his wife, (where he sustained the hearing impairment) he retired from filling tanks.

In a similar Rocket experiment a dive shop owner at Lake Whitney was very lucky just to get a broken arm due to his proximity to the launch pad. His aircraft surplus hydraulic accumulator lid was not latched firmly in place by its retaining ring after he changed the filter media. Upon almost reaching full pressure there was a lift-off that spawned a new nickname for his shop.... "Cape Whitney". The escape velocity was slowed only a little by his roof, but he was injured and the shop was a mess. Legal action ensued, and the supplier of the compressor system had to fork over a little $ in spite of the fact that the shop owner admitted he must have erred in his installation of the retainer.

I'll save some other grisly stories from the past 6 decades for later.
"I get plenty of excercise just pushing my luck!"

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ScubaLawyer
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Re: Condenser Towers vs. Filter Towers

Sun Apr 08, 2018 1:56 pm

Thanks Bill! Appreciate the insight. The whole air compression and filtration process is slowly starting to sink into my feeble brain. Trying to avoid all the compressor-go-boom stuff. :D
"The diver who collects specimens of underwater life has fun and becomes a keen underwater observer. .. seek slow-moving or attached organisms such as corals, starfish, or shelled creatures." (Golden Guide to Scuba Diving, 1968) :D

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Re: Condenser Towers vs. Filter Towers

Mon Apr 09, 2018 9:46 am

- Good question Mark. Having recently rebuilt my Back Pressure Regulator and re-read the Compressor 101 article on this forum, I was wondering about this: My RIX SA3-E has an original Back Pressure Regulator (BPR) after the condenser towers and before the filter array (that was added later). Bill put together the filter array for me and it has a PMV right after the filters. So, I essentially have two PMVs, too.

- The article says a properly set up PMV will remove 99.3% of the moisture from the air from simple condensation. It also says the 13X sieve does not have very much capacity to absorb what's left. So, I like the idea of separating the 13X sieve to a second PMV zone... Like, "Lets get all the water out before we go to the next operation".
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hunterkz
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Re: Condenser Towers vs. Filter Towers

Fri Apr 13, 2018 12:57 pm

My new to me compressor should be here Monday. I also ordered a hydraulic aircraft accumulator of 50ci to turn into a filter tower, back pressure valves, a FULL bottle of oil and a check valve. The Cornelius doesn't have an after cooler before the only filter separator and only a short run of tubing. From what I read the cooler the air coming into the separator the better for getting rid of water. What do you guys think of making a large coil out of NiCop 1/4 inch tubing before the separator to cool the air as much as possible? I would run a box fan pointed at the compressor while running to aid in keeping everything cool. Any suggestions?

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Re: Condenser Towers vs. Filter Towers

Fri Apr 13, 2018 1:35 pm

Hi Gary:
Sounds like you're moving right along with your compressor project. :D As for the addition of the cooler you're speaking of adding I really don't think it's necessary with this compressor. The reason I say this is because you stated that you were going to add that extra tower filter/separator similar to what I have. When I'm filling tanks I hit the blow off valves about every 15 minutes on the compressor and the tower I bought from Jim Shelden. I get the usual as expected condensate from the small separator/filter on the compressor and absolutely ZERO from the tower I added; just clean dry air. Once again I've had very little experience with compressors and the one I have is my first; so there may be some things I am not aware of and your idea of adding an additional cooler may be an excellent idea. Let's wait to see what our "Compressor Advisors" have to say about your idea; I'll be interested in that info myself. Good luck with your project! :D 8) Terry
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SurfLung
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Re: Condenser Towers vs. Filter Towers

Thu Oct 18, 2018 10:22 am

Re-Plumbing Can Help
- Last Spring I rebuilt my RIX Back Pressure Regulator (BPR) with rebuild parts from August Industries. When I got inside, I noticed it was dirty, rusty, and possibly moldy from moisture that just seemed to be constantly present. Looking at the way it was originally plumbed, the air outlet was coming out the bottom of the BPR... Where naturally any moisture in the line would settle. And this air outlet went directly to my filter array.
- In the past, I would drain the condensed moisture from the two condenser towers and occasionally I get some moisture out of the first filter array petcock as well. So, there was still condensable moisture in the line after going through the two RIX condenser towers.

- Examining the Plumbing... It occurred to me that I ought to have the air outlet on the BPR going upward instead of out the bottom where the moisture accumulates. Then, I put a moisture drain valve on the bottom of the BPR. This is the extent to my "Re-Plumbing".
Image

- The result of this was that when I'd drain the two condenser towers, I'd also drain the bottom of the BPR and sure enough, I got significant moisture out of that little bleeder valve. But now, that moisture wasn't finding its way into the filter array because the petcock up there was not having ANY moisture come out of it.

- I'm going to be checking the moisture strips on my filters pretty soon and it will be interesting to see how the color may differ from previous years.
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Re: Condenser Towers vs. Filter Towers

Thu Oct 18, 2018 12:32 pm

Good idea, and glad to hear it made a noticeable difference. You are always thinking! I'll keep this in mind when I'm configuring stuff :D
Thanks for the info.
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Re: Condenser Towers vs. Filter Towers

Thu Oct 18, 2018 1:49 pm

(I'm thinking Bill "bumped" this for my edification)

Glad this percolated to active again as I too am working through a solution with Bill. My ancient Baure/MAKO is about ready to be plumbed up thanks to some great advice. The original water separator (steel vessel) is remaining on duty, and the original steel body filter (is a re-packable unit , housing only carbon) is to be utilized, but i am swapping out the media to 13x MS. From there, the original outlet will go through a visual moisture detector, a check valve, and is then being plumbed to a 3-unit hyper filter (N-S Research) with the final filter an activated carbon. All filtration is using UltraFilter cartridges for breathing air). Exiting the final filters leads to the pressure sustaining valve to make everything operate in a happy pressure level. Last step is a split outlet to a CO Monitor on one leg (which I now realize I can also monitor for moisture), and my fill whip.

Curious to see how this performs...

Bill has been such a great resource in getting this to a successful outcome!
Bob

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Re: Condenser Towers vs. Filter Towers

Fri Oct 19, 2018 10:26 am

Pinker Than Last Year...
- Well I took out my filters and was surprised to find the first one (13X Sieve) was completely pink. The last two years the strip has been only slightly faded from blue to light blue. Thankfully the second filter was just light blue. So they weren't completely used up but awfully close.
- It surprises me that with all of my improvements, I actually seem to have MORE moisture getting through to the filters rather than less.
- Of course, it's not all condensation and plumbing. Thinking back on it I DID have one 3-4 hour filling session during a really hot and humid day. I knew the compressor was running hot and I WAS draining a lot more moisture than usual from the petcocks. Maybe that's what did it. I'll make a note to check the indicator strips more often... Especially after filling during that kind of heat and humidity.
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Re: Condenser Towers vs. Filter Towers

Fri Oct 19, 2018 11:01 am

Some don't like to fill on humid and rainy days, but that doesn't deter me when I am ready to fill something. The separators do a pretty good job anyway, but its probably a good idea to tap them more often during wet conditions. Seems to me that the less water you have gurgling around in the bottom of a separator the less you will have splashing up toward the "dried air" outlet to the filter. JMO.
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