My RIX SA3-E

[tbone1004]

@SurfLung restricted to 1" outlet ports though which would likely cause flow restriction when used with a nitrox stick. I may put a T on top of my nitrox stick and use a pair of them though

 

[iain/hsm]

View attachment 513157
Again, virtually no specific information. Either at August or at the Bauer.

No problem. Its from a German company called Mann Hummel
Dont ask me the part number way too late for that from us lot.
Iain

 

[SurfLung]

Final Plumbing Refinement...

- This puts everything as close as possible to the outport of the moisture condenser. I could have gone vertical with the BPR but I like the way it is with air going up and condensation going down where I have another place to drain it off.
- I tried the PTFE thread sealant and not only made a mess of it but it ended up not sealing well. Took everything apart and re-assembled with 6 wraps of tape. No more leaks!
- I filled an AL80 to test it out and everything is working fine... Ready for Summer.

 

[tbone1004]

@SurfLung careful using the world final

 

[SurfLung]

Now Pumping 3.2 CFM...
- I'm very pleased with the fill rate on my RIX SA3 compressor. Last night I was refilling my Twin 38s and Richs Twin 50s. The 38s were empty so I was able to calculate actual fill time on 84 cf (10% over). At 3 cfm it takes 28 minutes. But last night it took only 26 minutes... That figures to 3.2 CFM and the RIX is spec'd at 3.0 cfm (on a good day!)
- I'm running just slightly under speed at 2260 rpm (2300 is spec).
- The main things I will point to for this excellent performance are:
1. My "Ring Refresh" process,
2. Cylinder wall cleanup,
3. New O-rings in the heads,
4. And reed valve cleanup in the heads.

 

[SurfLung]

I thought I'd respond to one of Tbone's comments in this thread rather than muddy the waters on the other thread: "...of note, peak efficiency does not mean peak speed. Peak efficiency will be considerably slower than top speed, no different than MPG's on your car. With your Rix, you were running at peak speed with a lot of losses so you were a lot less efficient, but if you are looking at true efficiency of the pump the name of the game is minimize losses, then find out where the power/heat/cfm balance out."

Hi Tbone, once again you are thinking on a different wave length than I am. My idea of efficiency is having my compressor work the way the manufacturer designed it to work. I know you probably have some complicated formula but MY FORMULA is real simple... Filling my scuba tanks as fast as my compressor is designed for is the most efficient use of my time... My time spent filling tanks and my time spent diving. That's what peak efficiency means to me.

I hope i haven't offended you by saying this. But I think sometimes you might intimidate people from contributing to the discussion because you get overly technical and maybe too theoretical. I have no trouble understanding Jim Shelden's or AntiqueDiver Bill's explanations. They are literally GIANTs in the field of compressors compared to the rest of us. But I have never seen them go into theoretical territory the way you do.

Again, I mean you no offense. But when I read your comment above, I went downstairs and used my RIX SA3 to fill a set of Twin 48s, another set of Twin 38s, and even a single 50... All from about 500 psi each... And all in 1 hour and 3 minutes. That little RIX is working perfectly and I have absolutely ZERO interest in slowing it down to satisfy some theoretical efficiency formula.

 

[tbone1004]

@SurfLung no offense taken, just trying to use the appropriate terms for what we're talking about. The design parameters of those compressors are usually not the most "efficient" in the actual definition of the term. Part of this is I have responsibility for some gargantuan compressors at work *2500cfm, 500hp beasts* and getting those to run the most efficient is quite involved. With the Rix for you it was getting it into proper working order by stemming the misc leaks and getting the RPM where it was designed to be. As an engineer it's a very different discussion and those guys are speaking largely anecdotally vs. from a true design side which is where the discussions that Iain and I have gotten into.
Running your car at redline is most efficient for your use of time, but not most efficient for the machine and that's where I was going.

 

[SurfLung]

This is where your comments lose credibility with me. Running my compressor at the design specifications is not red lining it... I see that as the same as running my car in the 55-70 mph range... That's what it is designed for.

And then to say that Mr. Shelden and AntiqueDiver Bill are speaking "largely anecdotally" is a contradiction of terms. Anecdotal means "not necessarily true or reliable, because based on personal accounts rather than facts or research". I would say exactly the opposite... They have decades of experience building and problem solving the compressors we're discussing and its all true and reliable because they've actually done it. You might more accurately refer to their information and advice as practical and proven... In other words true and reliable.

On the contrary, I think the "true design side" discussions that you and Iain get into are so hypothetical and theoretical... Because its all on paper or in your head. Until you've actually got your RIX SA6 compressors restored to working condition, none of your slowed down, re-designed concepts will be proven workable nor even of any practical value. Like the discussion you guys got into on the poor little Solberg Intake Filter.

Well I suppose I've gone and put my foot in it. Frankly, I had hoped to get into some interesting discussions on the ScubaBoard but TBone... Bless your heart... You seem to be the only one reading or responding to my posts. I do appreciate it. And again I hope I haven't offended you or anyone else.

 

[tbone1004]

@SurfLung no offense taken, however those guys are not engineers, so their comments are from repairing them for years and years. Not discounting them because that information is incredibly useful but when I talked to the guy at Rix who actually designed the SA series compressors, the discussion was that they are essentially redlined and running at maximum RPM because the Navy needed them to fill as fast as possible, longevity be damned. The Kidde compressors will likely be the same because they were in aircraft and would have had fairly frequent replacement/rebuild schedules and the goal there is to minimize the size/weight of the pumps. All compressors run better when they run slower because they generate less heat and that's a simple engineering fact and understanding where these compressors come from originally and what they were designed for which is very different than say a continuous duty Bauer, Rix, etc. which are all designed to run much slower to save on heat.
My SA6 will be done in about a month, however slowing it down as I've said in my build thread is due to power concerns to keep it running on 110v instead of 220v as well as noise concerns. The Rix is loud, the Kidde is even louder.

 

[SurfLung]

Wow. That is truly incredible that you know the designer of the RIX SA compressors personally and all the more so because he agrees with you that they are running on the ragged edge of failure when pumping at factory specs. I got the exact opposite impression when I talked with the customer service department a few months ago. Reliability and field serviceability seemed to be the main goals to the military... RIX had no problem at all with me running at full speed. But who am I to argue with a guy who consults directly with the RIX designer. What's his name BTW?... I'd like to call him up and thank him for his good work designing my RIX SA3... I absolutely love it.

P.S. In the past, I have sent thank you notes to the two Erics and Christa for their help with my RIX.