robmwpropane
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Joined: Tue Oct 13, 2020 1:35 pm
First Name: Robert

Rix Vibration

Sun Jan 15, 2023 10:27 am

Good day all. I have a Rix that oscillates (if that's the right word?) when running. I believe it comes from the motor and not the compressor but I could be wrong. It's ran from a Yanmar diesel engine (which might be the loudest small engine in existence!)

The "cage" that the Rix is in will vibrate and then be calm and repeat this until I shut it down. It's not enough to walk across the floor, but I was just wondering if there was anything I could do? Maybe this is normal from a small diesel engine.

I have read everything by @Surflung and he has some great pointers / ideas. Just curious if anyone has any other insight?

I have plans to rebuild all the 1st and 2nd stage and all 3 heads with genuine Rix parts in the next month or 2. I am taking a tech class and tearing the compressor apart would be foolish until after.

Right now she pumps right @ 5cfm all the way until I shut it down @ 3900psi or so depending what tanks I'm filling. If I didn't get any blow by from the 2nd stage (only heard when off so I'm not sure if it's doing that while running), or the vibration I would say she runs perfect.

My ultimate goal would be to just maintain her so she runs happy for life! I am quite content with the convenience so far.. one of the best decisions I've ever made. At some point I will post some pictures of my setup.

Thanks all... I have learned a lot from reading through this forum.

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antique diver
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First Name: Bill
Location: North-Central Texas

Re: Rix Vibration

Sun Jan 15, 2023 3:06 pm

robmwpropane wrote:
Sun Jan 15, 2023 10:27 am
Good day all. I have a Rix that oscillates (if that's the right word?) when running. I believe it comes from the motor and not the compressor but I could be wrong. It's ran from a Yanmar diesel engine (which might be the loudest small engine in existence!)

The "cage" that the Rix is in will vibrate and then be calm and repeat this until I shut it down. It's not enough to walk across the floor, but I was just wondering if there was anything I could do? Maybe this is normal from a small diesel engine.

I have read everything by @Surflung and he has some great pointers / ideas. Just curious if anyone has any other insight?

I have plans to rebuild all the 1st and 2nd stage and all 3 heads with genuine Rix parts in the next month or 2. I am taking a tech class and tearing the compressor apart would be foolish until after.

Right now she pumps right @ 5cfm all the way until I shut it down @ 3900psi or so depending what tanks I'm filling. If I didn't get any blow by from the 2nd stage (only heard when off so I'm not sure if it's doing that while running), or the vibration I would say she runs perfect.

My ultimate goal would be to just maintain her so she runs happy for life! I am quite content with the convenience so far.. one of the best decisions I've ever made. At some point I will post some pictures of my setup.

Thanks all... I have learned a lot from reading through this forum.
Oscillation? Ha....that single cylinder diesel is more like a severe Pounding! I think your compressor is probably fine, and thankfully it is partly isolated from the pounding by the drive belts instead of being a direct drive.

About the blowby concern, if you are getting 5 cfm at 1500 RPM I doubt that your Rix second stage is in a failure mode. A very knowledgeable friend I have in the compressor business suggests that the blowby volume at stop commonly exceeds the volume at running speed. I hope he is right.

That said, I think you will learn a lot more than I know about the Rix when you do the overhaul! I could use your knowledge gained from that when I am faced with an overhaul on mine. Keep us posted.
The older I get the better I was.

robmwpropane
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Posts: 4
Joined: Tue Oct 13, 2020 1:35 pm
First Name: Robert

Re: Rix Vibration

Sun Jan 15, 2023 4:04 pm

antique diver wrote:
Sun Jan 15, 2023 3:06 pm
robmwpropane wrote:
Sun Jan 15, 2023 10:27 am
Good day all. I have a Rix that oscillates (if that's the right word?) when running. I believe it comes from the motor and not the compressor but I could be wrong. It's ran from a Yanmar diesel engine (which might be the loudest small engine in existence!)

The "cage" that the Rix is in will vibrate and then be calm and repeat this until I shut it down. It's not enough to walk across the floor, but I was just wondering if there was anything I could do? Maybe this is normal from a small diesel engine.

I have read everything by @Surflung and he has some great pointers / ideas. Just curious if anyone has any other insight?

I have plans to rebuild all the 1st and 2nd stage and all 3 heads with genuine Rix parts in the next month or 2. I am taking a tech class and tearing the compressor apart would be foolish until after.

Right now she pumps right @ 5cfm all the way until I shut it down @ 3900psi or so depending what tanks I'm filling. If I didn't get any blow by from the 2nd stage (only heard when off so I'm not sure if it's doing that while running), or the vibration I would say she runs perfect.

My ultimate goal would be to just maintain her so she runs happy for life! I am quite content with the convenience so far.. one of the best decisions I've ever made. At some point I will post some pictures of my setup.

Thanks all... I have learned a lot from reading through this forum.
Oscillation? Ha....that single cylinder diesel is more like a severe Pounding! I think your compressor is probably fine, and thankfully it is partly isolated from the pounding by the drive belts instead of being a direct drive.

About the blowby concern, if you are getting 5 cfm at 1500 RPM I doubt that your Rix second stage is in a failure mode. A very knowledgeable friend I have in the compressor business suggests that the blowby volume at stop commonly exceeds the volume at running speed. I hope he is right.

That said, I think you will learn a lot more than I know about the Rix when you do the overhaul! I could use your knowledge gained from that when I am faced with an overhaul on mine. Keep us posted.
Appreciate the feedback. Yes Sir, I suspect that the "pounding" is coming from the Yanmar. That thing is an absolute beast, but you can probably hear it from your house, lol.

I have read in the manual that blowby at stop is common (how much I don't know), but it makes sense that there is more at stop then while running (although no way to really measure that). It is a subtle but steady hiss from cylinder 2.

I do have interstage gauges on both the 2nd and 3rd stage coalescers and both read as per Rix chart while running.

I have a friend letting me borrow the 3rd stage ring compression tool, so hopefully I will be able to post some pictures soon of all pistons pulled out, then I'll really know what condition it's in. I'm just trying to be proactive in the GM of the machine.. I want hassle free sweet air for years to come!

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captain
Plank Owner
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Joined: Mon Jul 04, 2005 11:32 am
Location: LaPlace, LA

Re: Rix Vibration

Mon Jan 16, 2023 12:05 pm

I think the oscillation you are describing is the result of harmonics. The compressor and the engine each vibrate at a different frequency. Because each run at a different speed somewhere the frequency and amplitude of each merge and un-merge and each reinforces the other when merged.
I learned a lot about this when I was a sonar operator in the Navy but have forgotten much of it. We used harmonics to identify things like the class of submarine, diesel or nuclear propulsion, number of blades on the props, speed, etc.
On twin engine boats you can hear and feel when the engines become synchronized. Same with multi engine propeller airplanes.
Captain

robmwpropane
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Joined: Tue Oct 13, 2020 1:35 pm
First Name: Robert

Re: Rix Vibration

Mon Jan 16, 2023 12:20 pm

captain wrote:
Mon Jan 16, 2023 12:05 pm
I think the oscillation you are describing is the result of harmonics. The compressor and the engine each vibrate at a different frequency. Because each run at a different speed somewhere the frequency and amplitude of each merge and un-merge and each reinforces the other when merged.
I learned a lot about this when I was a sonar operator in the Navy but have forgotten much of it. We used harmonics to identify things like the class of submarine, diesel or nuclear propulsion, number of blades on the props, speed, etc.
On twin engine boats you can hear and feel when the engines become synchronized. Same with multi engine propeller airplanes.
Makes a lot of sense. Is this at all an issue? Could it cause damage? The rubber feet seem to soak up the majority of it.

What's interesting is that (to my naked eye and absolutely no science at all) after it reaches ~ 3000psi or so it doesn't seem as bad.... either that or maybe by that point I'm used to it!

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captain
Plank Owner
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Joined: Mon Jul 04, 2005 11:32 am
Location: LaPlace, LA

Re: Rix Vibration

Mon Jan 16, 2023 12:40 pm

Possibly at high pressure it slows an that effects the amplitude of the harmonic. I don't think it can cause damage.
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robmwpropane
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Posts: 4
Joined: Tue Oct 13, 2020 1:35 pm
First Name: Robert

Re: Rix Vibration

Mon Jan 16, 2023 1:29 pm

Thank you. It's been interesting learning about this little compressor. Just built different.

I didn't think the vibration was an issue, but with as much engineering went into the build you would think they would have engineered that out.

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