Tore My Rix SA-6B Apart

[rob.mwpropane]

You could always widen the grooves to spec.. in a lathe of course.

seems like your piston is an older version... or something

I'd like to find out what before I do anything. Seems odd. Interested to see what insight Iain has.

I have never come across anything about different revisions of the piston. To top it off, as far as Rix SA-6 go, mine is pretty new with all the latest revisions. It would be different if it was 30 years old, idk.

 

[rob.mwpropane]

When I'm back at the works Monday I will look into this

Iain

Any news good Sir?

 

[iain/hsm]

If the "new" way is to just add another 2 compression rings then why are we all still passing around an outdated manual? Heck, that's even the same manual that Rix sent me in ~ Oct. when I placed the order?

To answer the question of you being suppling outdated manuals.
The manual issued with the compressor when supplied new is the manual for that compressor serial number or build spec throughout its working life. And if the compressor is 20 or even 30 years old you will get the same 30 year old manual as when it was new.

Now if the original compressor is subsequently sold the manual for it still remains the same manual. The concept of outdated manuals passing around is not a valid criticism.

Now depending on the serial number pressure flow gas type and application some parts of a new build compressor may be the same as your build or maybe different, But again the manual for that new build will be different to yours with components listed dependant on the build serial number.

Further confusion can occur if customers keep calling it an SA-6. As illustrated below and wondering why the parts are different. Hope this clears up the outdated manuals issue. Iain

 

[iain/hsm]

I would have preferred to do it right and not have to have waited the 3 months.

If the "new" way is to just add another 2 compression rings then why are we all still passing around an outdated manual? Heck, that's even the same manual that Rix sent me in ~ Oct. when I placed the order?

The 3 months wait for this part the Pressure Breaker Ring is probably due to you having an older compressor with a low parts turnover coupled with a material long lead time.

You can also blame computer minimum stock levels for this.

In addition commercial customers will buy in 100's at a time and if the current stock is approaching low it is not uncommon for someone who buys 100's when finding low stock will buy the entire stock remaining in one hit to ensure their compressor service contract obligations.

But computer stock levels would be my culprit here coupled by obtaining a specific say 20 year old polymer compound that is rarely used in the general engineering world and to a specific blend.

An old piece of advice comes to mind here. Carry spares and planned maintenance. Iain

 

[iain/hsm]

Thank you. What about the addition of o rings under the new compression rings?

Two important points.
1. If you use the original pressure breakers ring you don't use 0-rings under the seal.
2. If you decide to use a conventional compression ring as the other rings you do use the 0-ring under Iain

 

[-JD-]

[snip] We stopped using them some time back at the Skunk works and use for our current builds just two additional pairs of compression rings instead.[snip]

Is there a marked improvement in performance or service interval by using the additional 2 compression rings (in lieu of the pressure breakers) or is the change driven by simplification - i.e reducing the stocked part-number count and "monkey with a spanner" issues?

If performance/interval, would you judge it worth doing as an upgrade when doing some degree of tear-down, even if a 3rd stage rebuild wasn't otherwise warranted?

And where do we send the pint-money ...

 

[rob.mwpropane]

To answer the question of you being suppling outdated manuals.
The manual issued with the compressor when supplied new is the manual for that compressor serial number or build spec throughout its working life. And if the compressor is 20 or even 30 years old you will get the same 30 year old manual as when it was new.

Now if the original compressor is subsequently sold the manual for it still remains the same manual. The concept of outdated manuals passing around is not a valid criticism.

Now depending on the serial number pressure flow gas type and application some parts of a new build compressor may be the same as your build or maybe different, But again the manual for that new build will be different to yours with components listed dependant on the build serial number.

Further confusion can occur if customers keep calling it an SA-6. As illustrated below and wondering why the parts are different. Hope this clears up the outdated manuals issue. Iain

View attachment 831684

No criticism at all, I appreciate the insight. For what it's worth I gave Rix my serial number and these were the parts they sent.

They have asked me to send back the pressure breaker rings as they believe they might be out of spec, or at least that's what I assume because they were nice enough to rush out new parts and asked for the old ones back.

@iain/hsm I'm also curious to find out what the new service interval should be if going with 6 compression rings and 6 rider rings and if this in some way is considered an upgrade? I'm not even sure what purpose the pressure breaker rings serve?

 

[iain/hsm]

Is there a marked improvement in performance or service interval by using the additional 2 compression rings (in lieu of the pressure breakers) or is the change driven by simplification - i.e reducing the stocked part-number count and "monkey with a spanner" issues?

If performance/interval, would you judge it worth doing as an upgrade when doing some degree of tear-down, even if a 3rd stage rebuild wasn't otherwise warranted?

And where do we send the pint-money ...

No not really the advised service life is still around 250 hours either way hence the suggestion if you don't have the PB ring (pressure breaker ring ) on hand just use 2 additional comp rings to do the same job. You could also re use both the PB Rings but the $30 saving does have risks if the life is not doubled. And with no real labour cost saved.

Some more modern designs and another models have done away with the PB ring and additional compression rings have been used (I may show these later as examples)

Technically its not an upgrade its just a field application to get you up and running
Not withstanding if (and its a big if) the SA-3 and SA-6 were to be re introduced would you go with a compete piston re design or stick with the 1000's of rings already still available and cheap . Computer minimum stock levels permitting that is. As for the pint money forget it I don't drink besides you couldn't afford my rates LOL Iain

 

[Gone for diving]

An english man that doesn't drink.....

 

[iain/hsm]

You can see in this pic that there's no way I can fit that in there. Rix told me tolerances for that part are .070-.073.

View attachment 830695

Not so .070 to .073 that's way too tight however I did notice that the pressure compensation holes look smaller above where the pressure breaker rings fit. Do tell me that's not so and its just an optical illusion
Iain