Found It... Fill Rate is Now a True 2.875 cfm...
- Well the good news is I discovered what the problem is, corrected it, and the compressor filled a tank from 0-full at 2.875 cfm... That's the fastest fill rate it has ever achieved for me. Closest to the 3 cfm advertised by RIX... Its a RIX SA3 compressor. Nearly 2.9 cfm!
- The bad news is that the 3rd stage piston is broken at the bottom... There's the bottom rider ring and then the first compression ring... The break is through the first compression ring groove. I think it was being held together by the gummed up compression ring... It came apart in my fingers as I was pulling it out of the cylinder. Anyway, I'm going to have to get a new 3rd stage piston before I run it again.
- How did I run the 2.875 cfm test with a broken piston? Well, I got away with it but shouldn't have. I figured since it is a floating piston, and since the broke-off part has plenty of "Rider Ring" to keep it straight, and since it has already been running this way for what looks like awhile, it should work enough to see if the solution will fix the fill rate. The truth is, with the piston, rings, expanders, and riders all cleaned up, it rattled a bit and I attribute the rattle to the broken floating piston... Banging its parts together.
- Okay so what was the "Fix" - Well, when I pulled the 1st stage piston, I immediately noticed there was no resistance... no friction nor suction. Then I looked at the ring and it was completely compressed into the piston groove and gummy. The ring ends overlapped and actually pinched in the ring groove, holding the ring in the compressed state. Closer examination showed nothing wrong with the rings. It took awhile to free up the overlapped pinch with a razor blade. But I finally coaxed it loose and was able to remove the ring and expander O-ring beneath it. Both were in good shaped but gummed up. So, I cleaned them with warm water and Dawn dishwashing liquid. I snipped a bit of length off the ends so there won't be an overlap to pinch into the ring groove. When the expander and compression rings were re-installed, they were visually expanded beyond the piston diameter. And when I re-installed the piston into the cylinder, I could feel friction and compression properly.
- I experienced and did pretty much the same thing with all three pistons.
- So what caused the "gummed up" condition. Well, the grease used on the turn buckles is a special "low sling" type so as not to get flung around where it shouldn't be. But you can see and feel old grease residue on the bottom of the cylinders, piston rods, thrust bearing springs, etc. I believe this is what gummed up the rings. I'm thinking I should get a tooth brush and some Dawn and hot water to clean up the whole bottom of the compressor.
1. Ring failure doesn't necessarily mean you have to replace the rings. It costs $141 to replace all of the rings so, I'm glad it isn't always necessary. In this case, ALL of the rings were working in good contact after the clean up. Perhaps a good idea to check and service the rings (and heads) 1-2 times a year. Its not all that difficult to do with the RIX.
2. Turn buckle lubrication. You can do a much better job with the piston removed because you can rotate the ball and get fresh grease on all surfaces. AND, you can wipe off the excess before re-installing the piston and thereby reduce grease slinging.
3. I learned how to check for and adjust piston head gap... Didn't need to do it but, learned it while trying to find a solution.
4. I learned to use balloons or rubber gloves to check for leaks on over pressure valves (thanks Bill).
- I've got to call RIX today and order a new 3rd stage piston. Its $768 with all new rings installed. Or, $333 for just the piston. GEEZ! I thought the piston was brass but maybe its gold? If they have it on the shelf and can ship 2nd day air, I can have this compressor restored to proper running condition by next weekend. I don't need it that fast but it bothers me when its not running right. - Best Regards, Eben
P.S. - It occurs to me that anyone who has been following all of my trials and tribulations with this RIX SA3 compressor must think, "What a pain in the neck it must be to own a compressor." Or, "That RIX must be a piece of junk." I think I need to comment on that: Remember that this was a well used compressor that I bought awfully cheap. From the start, there were alot of non-standard issues with it that had to be figured out and corrected... By me, an absolute amateur at compressor service. With the help of my friend Bill the Antique Diver and others, I learned the working of this compressor as well as some general things about other compressors. I still don't know everything about this RIX. But I know alot more than I did when I started. AND, I've been filling tanks for 30-40 dives a year for the past 3-4 years that I've owned this compressor!
- It may be that a RIX has to be checked and service more often and in greater detail than I have done it. But the RIX is relatively easy to pull and service the heads and rings once you get the hang of it. Anyway, I have enjoyed filling tanks as well as learning to service my compressor.
- But that doesn't mean EVERY compressor is a pain in the neck. Buy a new one and you won't have to put up with an adventure like mine!
The Freedom and Simplicity of Vintage Equipment and
Vintage Diving Technique are Why I Got Back Into Diving.