Slow Fill Rate Solution...
- I started seeing a slower and slower fill rate with my RIX, starting last Fall I figured it was down to 2.2 cfm. And then this winter down to 1.8 cfm... This is down from a high of 2.7 cfm last winter. This is filling tanks in my cool and very dry basement (humidity less than 30%). After checking for leaks, belt slipping, clogged intake, etc. I could find no cause. So, I serviced the cylinder heads with cleaning and new O-rings. No change. Finally I had nothing left but to check the piston rings. Bottom line is that they were gummed up and stuck in a compressed state, not sealing very well at all. AND, the 3rd stage piston was actually broken into two parts.
- As usual, I ended up learning a heck of a lot from solving and repairing the problem. After servicing the rings, I did a fill rate test and set a new personal record of 2.875 cfm. I wrote it all up to post under the "Fill Rate Challenge" section of this forum. But I think its significant enough that I should also include it here under my general RIX SA3E thread:
RIX Compressors Are Different...
- I worked on the compressor Saturday and got the new piston installed and everything back up and running smoothly... Perfectly, actually. I learned a lot on this most recent challenge of solving the slow fill rate. And, I've been meaning to write it all down so I don't forget. To start with, probably the most valuable lesson here is that RIX Compressors Are Different. Certainly they share aspects of Air Compression with other compressors. But the "Oil-Less" compression mechanism has some unique aspects that I don't think the instruction manual completely explains.
- Teflon Rings:
There's no crank case filled with oil. The compression rings on a RIX are made of a teflon material that's flat and coils like a typical piston ring. BUT, it has no spring characteristics to keep it pressing outward to create a seal. Instead, it has an O-ring underneath the compression ring that provides all of the outward flex to seal the gas between the piston and cylinder wall.
- Teflon Rings Are Self Sacrificing:
They provide their own dry lubricant as they wear against the cylinder walls. The good news here is that the rings are what wear out, not the cylinder walls nor the pistons. And the rings are easily replaceable. The bad news is that as they wear, they produce a teflon dust residue. And if there is any moisture in the incoming air, it mixes with the teflon dust and starts gumming up the ring movement. I made a BIG mistake when I replaced all the rings last year... I used some of that food grade silicon spray lube to make the new rings slide into the pistons easier. That's right, I introduced moisture where I should have kept it dry. Over the Summer of filling tanks, my rings got gummed up more and more until they stuck in an almost totally compressed condition. And that's what made my compressor pump so much slower.
- Slow Pressure Can Break Things:
The 3rd stage piston on my RIX is "floating". It doesn't connect to its piston rod. The proper function is for the compressor to build pressure rapidly, forcing the 3rd stage piston to stay in contact with its piston rod. If this pressure doesn't build rapidly, the piston just gets hammered over and over until the pressure finally comes up. I believe this is what broke my 3rd stage piston. Now that I have the compressor running properly, I can actually HEAR the 3rd stage piston hit the piston rod once or twice before they settle into constant contact and become quiet. As was stated elsewhere, the first priority of the Back Pressure Regulator (on the RIX) is to build pressure rapidly so as to reduce hammering of the 3rd stage piston. I will add that its important to close all your drain valves before starting to assist in rapid pressure build.
- Keeping It Clean is Easy:
Following the RIX tech's advice, I scrubbed the cylinders with Dawn detergent, hot water, and a green scotch brite pad with bottle brush back-ups. Rinsed with a fresh water squirt bottle and air blast several times. Then, I scrubbed the piston rings on the pistons with a nylon toothbrush and Dawn with hot water. Lots of black gunk came out. I scrubbed until the suds remained white. Then, rinsed with fresh water and air blast. I let everything dry fully before re-assembly. This cleaning process allows you to watch as the rings get freed from their gunk, they start to expand outward and you discover that they're still good rings... You don't need to replace them. And since the RIX has no crank case, popping the pistons out for an occasional ring cleaning is pretty easy. You wouldn't need to do this on a conventional oil-lubricated compressor. BUT a RIX is Different.