My future RIX - Pre-Purchase Investigation/Inspection and Reconfiguration ?s

[-JD-]

Yea, I know another RIX thread ... I've read and followed most (all?) of the RIX threads on here and tried to integrate the narrated experiences of @tbone1004 and @rob.mwpropane in particular and the ongoing wisdom of @iain/hsm but there is always more to know.


At some point in the not too distant future, I am hoping to be in a situation that requires a compressor, so purchasing could be next week or a few years - all depends on if and when the "right" unit at the right price comes along. My likely target would be some variant of SA-6. I have some reconfiguration questions, but my real hope is to aggregate information that will allow for sound purchase decisions since buying a new pump does not seem to be an option going forward. As evidenced in my old thread on one found unit: There be pigs! (RIX SA-2: Is there such a thing?) and I don't want a money pit.


To get it out of the way, Reconfiguration/Modification:

• Assuming that the separator "towers" are re-plumbed to be orientated vertically, is there any reason that the pump can't be run in a vertical orientation? Would fan-up vs. fan-down matter, or is there a reverse-direction fan to pull rather than push if it would be convection/cooling as the limiting factor?
• Some uses (ex. 48VDC Power Systems with battery banks) lend themselves to quiet, compact, fumeless electric drive and I have found some 4kW, 1500RPM motors that might be a good match (understanding the 17% capacity reduction due to lower RPM). Is there any reason that the motor couldn't be mounted inline with a three-piece coupling (a flange adapter would need to be mounted to the drive-pulley face)?
• Does anybody have any experience with inter/after-cooling setups for lower operating temps and enhanced moisture extraction? Water-cooling is of particular interest in a marine application or as part of a bigger thermal management scheme in confined mounting situations.

Pre-purchase: Selection and Inspection:

• Assuming that most sellers are not going to allow the unit to be messed with more the pulling the shroud for inspection and what would otherwise be normal operation, are there any good tests beyond what @iain/hsm outlined in @rob.mwpropane 's Filter tower thread (Filter Tower Question) Strikethrough is not likely possible and underlined is alternate.

[snip]​

At the front of the cooling shroud in the 6 o'clock position is a small bolt running through the steel 1 inch frame that holds the shrould in place, remove it and clean any grease and muck inside, inspect the two rubber grommets at each side of the block that hold the back of the shroud in two half cups. Replacing the grommets are cheap the plastic shroud isnt.​

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Clean off any muck dirt and grease you can see and behind the main swach plate bearing and the 3 rose head bearings clean the 2 thrust rider plates (they are hardened steel and sharp) in the 6 o'clock position and note a small blue spring on the alignment trapeze right side.​

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Lever off the decop lever on the engine or better yet remove the belts and turn the pump slowly by hand clockwise when viewed from the fan end (front) looking like a hawk on that blue spring to see if it moves if it does you may be out of alignment. If not and its rock steady your good then re grease using polyura grease (blue) the thrust rider plates and the lower twin bearing race use your finger.​

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Next inspect the 3 rose head bearings at the end of each piston rod. Pull and push them checking for a loose race or worn if OK re grease them via the zerk grease nipples 5 pumps on the low pressure setting using an Alemet Pistol grip grease gun model 555-E dont waste your time using junk from China, if you do use a cheap nasty grease gun from your local Home Depot or whaterver you Yanks have that supports Chinese junk imports then you will understand where all that grease flinging about the place inside the fan shroud came from.​

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Check belts for tension open drain valves, fit air intake air filter at the end of a 1" OD 3/4" ID PVC flexible hose use food grade tubing it wont off-gas or smell use jubille clips to attatch each end.​

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Fit an interstage gauge (1500 psi range) to the second stage relief valve​

Fit HP charging line with a pressure gauge to say a scuba cylinder with the valve closed at all times and fire it up.​

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Run for 10 seconds then close the two drain valves and see if it builds up pressure. At 3000 psi or near to open the 3rd stage bleed valve for five seconds then close it then open the 2nd stage bleed valve also about 5 seconds​

At the same time collect the discharge water from each stage drain and inspect for junk and stuff later​

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While the compressor is running you can use the 3rd stage bleed to throttle the flow and not exceed the say 3000 psi or the relief valve will open. But keep it at a minimum 500 psi. Then when you are ready close all the drains and if required let it run back up to 3000 psi . Then stop the engine.​

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While stopped but still under pressure wait for 10 seconds check for leaks. Specifically on the 2nd stage intermediate gauge if its rising then your 3rd stage inlet valve is leaking back high pressure, if its falling then the 2nd stage discharge valve is leaking back. Then check the HP 3rd stage gauge if its falling then you have a leak or the inlet valve is weeping back,​

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Conversly if the 3rd stage pressure is still rising then the engine is still running and your deaf.​

That or the gauge needle is in the process of falling off.​

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If you dont have a second stage gauge fitted a cheap alternative trick is to drain the 2nd stage to empty while the 3rd stage is full but then re close the 2nd stage drain valve and wait another 10 seconds and open again, if the 3rd stage inlet valve is leaking back you get a clue if more air drains out of the 2nd stage separator after a 10 seconds hold from empty.​

[snip]​

• Is there any reference sheet available that would help me to determine if it is a "late" model with the improvements and good parts support/availability based on model/serial numbers?
• Are all versions OK to run for HP/Cave fills with 3rd stage OP valves adjustable to 3800psi?

 

[tbone1004]

Pump can be run in any orientation so long as it has adequate ventilation for cooling. The condensers are obviously orientation sensitive so you will need to reconfigure their mounting brackets.
The fan moves enough air that there is no "convection" going on, it's moving the air way too fast. You can always remove the mechanical fan and replace with an electric fan.

If you intend on running it from batteries then a 48vdc brushless motor *basically acts like a 3-phase AC motor* will be sufficient. Stock motors are 3600rpm motors so if you want to maintain the same pulley ratios and output then keep it around 3600rpm though you can change pulleys obviously to get whatever pump speed you want. You could direct drive it with a lovejoy coupling, no reason you couldn't. Not sure you'd have any real benefits unless the packaging is dramatically improved.
Most of the pumps in any sort of "real" use have remote mounted condensers and filters. Remember that the stock pumps were called "sweet air" since they didn't have any filtration, only the water traps. Adding another condenser and filter stack is prudent, particularly if you are running steel tanks. No real need to have extra cooling between the stages unless you are running in crazy parameters of heat and run-time.

Serial numbers will dictate its original variant and you can crosscheck that with Rix directly, they are quite helpful.
All versions OK to run to 4000psi. I wouldn't necessarily run them that high to fill a large bank system, but they don't care about running to 4000psi.

 

[-JD-]

Yea, packaging is a big driver. I have seen some 1500RPM 4KW 48V BLDC "pancake" motors of similar diameter to the pump and quite short - benefit of the electro-motive trend. With direct-drive, the packaging could be very efficient. Oriented vertically it would be easy to add a filter tower with minimal volumetric increase. Mount it all to a thick machined hunk of aluminum and "wall mount it ...

 

[rob.mwpropane]

This is all beyond the scope of my knowledge, hence why I haven't commented. My RIX is ran from the worlds loudest diesel engine.. seriously I have to wear ear muffs and even then it's still stupid loud.

I added an additional filter tower as the RIX out of the box wasn't capable of delivering dry air. I also added some interstage gauges to see what the 2nd and 3rd stage are doing and keep them in check.

After really looking at the RIX I think it's a pretty ingenious design. Easy to work on. Nice that it can operate in any orientation. The kicker is parts are stupid expensive or scarce. It's a shame that it wasn't picked up or copied and sold more. If it wasn't for parts it really is the perfect compressor for any diver.

Mine is a much later design, as far as I can tell it's the newest revision. The giveaways are SS lines, dual belt, and SS heads. Easy to see all pulling the covers off.

Now for the kicker... I want to dive for a long time. I really love my RIX and I do everything I can to keep it happy. I add the correct grease every 15 hours or so (manual says 50?) and check the engine oil before each start...but... If I had to do it over again I think I would have bought a bauer.. I'm sure if I searched long enough I would have come along a firehouse getting rid of one. This will be how I will feel the day my RIX dies anyway.... I hope that's a long ways off. I am told a Bauer will last 1000's of hours and my RIX (3rd stage anyway) will need rebuild at around 1000 hours... and since I have no way of knowing how many it had when bought, I really don't know.

Hope that helps.. more than happy to send pics of everything I have. You're not that far... if you ever want to swing down I'd be happy to show it to you and answer any questions that you have. Zip is 21132

 

[-JD-]

Thanks for that, Rob. I've read your threads and there are a lot of great nuggets in there. And I hope to get to see your setup at some point ...

Would you mind sending me (PM is fine) whatever identifying stuff is on you unit? It might give me hints on if a particular unit is 'newer' when I find one for sale.

There were hints that new pumps might be available at some point. I keep hoping ... I could really see Brownies or some organization building them into ultra-compact units for marine applications.

 

[tbone1004]

Yea, packaging is a big driver. I have seen some 1500RPM 4KW 48V BLDC "pancake" motors of similar diameter to the pump and quite short - benefit of the electro-motive trend. With direct-drive, the packaging could be very efficient. Oriented vertically it would be easy to add a filter tower with minimal volumetric increase. Mount it all to a thick machined hunk of aluminum and "wall mount it ...

Filter can be remote mounted if it's more convenient. You'll want to fit autodrains if it's in an inconvenient compartment, but the filter an go wherever is convenient.
Be careful with wall mounting as it does need considerable airflow so you'll want to stand it off the wall a bit if you can and/or change to an electric fan that moves more volume than the stock pump.
Since it sounds like this is on a boat, if you have a big hydraulic pump already it can direct drive off of a hydraulic pump

@rob.mwpropane the 1000hr mark is still 360k cf of gas.... A pair of avid divers doing 3x recreational dives per weekend will use optimistically 1000cf in a weekend so that's 360 weekends, 7 years if you dive ever weekend. The Bauer can certainly go considerably longer but for a home use pump it's one of those things that does exist but doesn't particularly matter. The reason I bought one is because it is bigger/faster to fill banks but I still love my pair of Rixes and think that they really are the best option for most home users, especially since they are relatively "idiot proof" in terms of gas quality since they are oil-less.
How many hours are on the hour meter? Odds are it's on the original 3rd stage but you'll know when the 3rd stage needs to be replaced since it will start bleeding by so you'll see lower cfm at higher pressures or it won't be able to build pressure fully.

 

[rob.mwpropane]

Thanks for that, Rob. I've read your threads and there are a lot of great nuggets in there. And I hope to get to see your setup at some point ...

Would you mind sending me (PM is fine) whatever identifying stuff is on you unit? It might give me hints on if a particular unit is 'newer' when I find one for sale.

There were hints that new pumps might be available at some point. I keep hoping ... I could really see Brownies or some organization building them into ultra-compact units for marine applications.

Let me know.. come on down anytime and if you're up for a quarry dive we can make a day of it!

There's really not much to identify them. There's a sn under the shroud. Mine is hard to see through the coils. The duel belt is probably the easiest giveaway that it's a newer unit.

In these pics you can see the data plate on top, the SS coils, and the duel belts.

@rob.mwpropane the 1000hr mark is still 360k cf of gas.... A pair of avid divers doing 3x recreational dives per weekend will use optimistically 1000cf in a weekend so that's 360 weekends, 7 years if you dive ever weekend. The Bauer can certainly go considerably longer but for a home use pump it's one of those things that does exist but doesn't particularly matter. The reason I bought one is because it is bigger/faster to fill banks but I still love my pair of Rixes and think that they really are the best option for most home users, especially since they are relatively "idiot proof" in terms of gas quality since they are oil-less.
How many hours are on the hour meter? Odds are it's on the original 3rd stage but you'll know when the 3rd stage needs to be replaced since it will start bleeding by so you'll see lower cfm at higher pressures or it won't be able to build pressure fully.

I did the math and I know you're correct. Mine didn't come with an hr meter. I know how many hours I've put on it since I bought it, but no idea what was on it before. I was a little lucky in that it had service records from 2015 and I bought it before the world lost it's **** in 2020, so the price wasn't too bad. If I had to throw $1000-$1500 at it in a few years I will and it'll be ok.

I I love my RIX, I really hope to get a long time out of her. I agree, simple design and almost idiot proof. I love the feeling of being 100% independent of any dive shop. Even though I have yet to take it anywhere it is about as portable a machine as any. It's not exactly fast, but it's not exactly slow either.

Right now I have slight blow by via the 2nd stage, not sure how common that is but my gauges all read what they're supposed to while running. Everyone I've talked to said some is ok. I don't have any loss of cfm after being timed for a while (on multiple occasions), always on the money.. I can only hear the blow by when the unit is off and before I drain the coalescers obviously.

Question for anyone... do you leave your filter tower pressurized? I'll drain mine to say ~ 2500-3000 psi but I jsut let it sit like that.. no reason not to right? I ask as I met a guy recently that has a compressor that runs on propane (got me excited!!) but he drains his tower after every use because he keeps it in his garage... I thought that killed the filter faster not to mention you have to pump it all the way back up? Thoughts?

 

[tbone1004]

Leave the filter pressurized. No need to blow it down to any particular pressure. Cycles are what kills them so letting them fall down is not productive in the slightest.

 

[PrffsrE]

I second everything tbone said! (Wait what did he say? LOL) Just a few more cents from a lover of RIX, a maintainer of RIX and a realist.

If you purchase an original SA-6. If you ever have needed repairs. You will likely have to replace some parts with entirely new model parts. like the, cooling lines and 3rd stage valve. If the valve goes bad you will need to purchase a new head! (I dealt with that one) If you are considering an original SA-6. Get a smoking deal!

On another note. I watched a video of a guy that ran his 2hp compressor on a sailboat from a 3000 VA victron inverter. He replaced the single phase 2hp motor on a Bauer with a 3 phase motor and added a frequency drive to run it. (I do not think he preformed the work. I think he had it done.) A few things he did not cover. I assume the inverter was outputting 240 volts (mine is 120). All that said, It would be much easier and more efficient to put a DC motor on it. But as mentioned you would need 48 volts. (My boat is all 12 volts) I will include the link.

 

[tbone1004]

@PrffsrE while the DC system would remove the inverter and VFD losses, it's quite a bit more complicated than that. You couldn't run the motor directly off of battery voltage because with DC motors their speed is directly proportional to voltage so you would still need some sort of controller to provide stable voltage and finding adequately sized BLDC motors and controllers is going to be much more irritating than buying a standard off-the-shelf common in basically every country in the world 2hp 3-phase motor.
I haven't watched the video, but he is definitely using the VFD for phase conversion. While the Multiplus unit he is using as an inverter can be configured to run in parallel, split-phase, or 3-phase configurations he doesn't have 3 of them in there so the VFD is handling phase conversion which is ideal because even with those efficiency losses in the inverter and VFD he is still net more efficient than running a single phase motor. Many of the boat people tend to put 230v inverters in because it lets you run much smaller wires and if you're anywhere but the USA it's advantageous so it's probably a 230v/50hz inverter.

If you're in the USA and you want to use your 120v inverter or an extension cord to run a 3-phase motor, they make them up to 1.5hp. 1p 120vac in. I have one running my Rix SA6, albeit at a third of its rated speed, and they're also used to run things like Masterline boosters with variable speed, small shop tools like lathes and milling machines, etc. Plenty of Youtube videos on how to configure them for phase conversion. Also using the VFD for phase conversion is the right way to use large compressors in areas without 3p power, converting them to single phase is definitely not the right now way to do it.

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