Rix SA-6 Parts

[rob.mwpropane]

I have had to fabricate new cooling line for many different compressors over the year. The finned lines are to maximize heat dissipation in a small area. Size is important in a portable compressor. There are spreadsheets to calculate the heat shed in a finned line vs smooth stainless. You can replace the finned line with smooth, but it will need to be much much longer. On a fixed compressor, it isn't an issue. On a portable machine, it is a huge issue. I have extended intercooler lines on fixed compressors to run them through a water bath in tropical locations, it is an excellent way to shed heat when you are directly on the ocean.

I have seen the finned cooling lines, just not on a Rix.

I use an industrial fan blowing into the shroud to help with heat.. I know that was a shortcoming of the Rix.

 

[PrffsrE]

I just found this great brochure that covers the SA line of compressors.

Please note I used and maintained the last compressor on the brochure. The 4 VX. I have been receiving DM's saying: "That the SA-6 is a little small for a dive shop!" LOL We had 24 CFM version.

http://www.cryoquip.com.au/store/catalog/RixDiving.pdf

 

[rob.mwpropane]

I just found this great brochure that covers the SA line of compressors.

Please note I used and maintained the last compressor on the brochure. The 4 VX. I have been receiving DM's saying: "That the SA-6 is a little small for a dive shop!" LOL We had 24 CFM version.

http://www.cryoquip.com.au/store/catalog/RixDiving.pdf

I always thought it was funny that that brochure says "Easy to Breath Humid Air"

 

[iain/hsm]

I use an industrial fan blowing into the shroud to help with heat.. I know that was a shortcoming of the Rix.

I guess resemble that remark LOL but I am not aware of any engineering shortcomings

I have seen the finned cooling lines, just not on a Rix.

You have now.

 

[iain/hsm]

Please note I used and maintained the last compressor on the brochure. The 4 VX. I have been receiving DM's saying: "That the SA-6 is a little small for a dive shop!" LOL We had 24 CFM version.

The 4V is also oil free but to be fair it does use a fair amount tea to get it going in a morning. (It's an English thing some may have difficulty understanding LOL)

 

[rob.mwpropane]

I guess resemble that remark LOL but I am not aware of any engineering shortcomings

So more air over the heads wouldn't be better for cooling?

Also, I sent you a PM about parts.. not sure if you saw it.

 

[tbone1004]

So more air over the heads wouldn't be better for cooling?

Also, I sent you a PM about parts.. not sure if you saw it.

Better is subjective, but I'm with @iain/hsm on this. If you operate the SA-6 in its originally intended scope then it certainly has adequate cooling for a portable compressor that is designed for intermittent/short duty cycles to ~3000psi. If you run it outside of its original scope and start using it to fill large doubles to 4000psi or start filling cascade bottles with it to 4500psi then it's going to generate some serious heat, but that's outside of its original design parameters so I wouldn't consider it an engineering shortcoming.
Also, finned cooling tubes on a portable compressor would be nothing short of a nightmare!

 

[rob.mwpropane]

Better is subjective, but I'm with @iain/hsm on this. If you operate the SA-6 in its originally intended scope then it certainly has adequate cooling for a portable compressor that is designed for intermittent/short duty cycles to ~3000psi. If you run it outside of its original scope and start using it to fill large doubles to 4000psi or start filling cascade bottles with it to 4500psi then it's going to generate some serious heat, but that's outside of its original design parameters so I wouldn't consider it an engineering shortcoming.
Also, finned cooling tubes on a portable compressor would be nothing short of a nightmare!

I am pretty sure I have read on here and elsewhere the Rix SA-6 is continuous duty to 3600psi?

 

[iain/hsm]

I have seen the finned cooling lines, just not on a Rix.

I use an industrial fan blowing into the shroud to help with heat.. I know that was a shortcoming of the Rix.

Just a heads up here on the SA-6 from an engineering design perspectives and to ensure you there is no shortcoming from the engineering.

The suggestion of using a finned heat exchanger on the SA-6 production on an oil free compressor would be counter productive. Your dealing with many additional engineering considerations. I give you one. We have only eight more to go.

Cooling too much is more of a problem than cooling just enough when compressing a condensing gas like atmospheric air. Oil free air in a reciprocating multi stage compressor will cool the gas very rapidly by contrast to trying to cool oil saturated air from an oil lubricated compressor. Assuming your comparing using the same cooling tube internal diameter, the same wall thickness and the same cooling coil length. And also important at the same gas velocity.

Other factors such as the compression ratio , blow by, piston stroke, piston diameter, etc also play an important role the other factors are approach temperature considerations.

A simple example being the time taken to cool a kilo of water or a kilo of oil in a steel container from say 100C to ambient (say 21C) just by standing them out in atmospheric air and wondering which will cool quicker.

If you need a deeper explanation no problem I just feel that sometimes the engineering is a little too boring for the real world, but its not a shortcoming. It's a skill.

 

[iain/hsm]

So more air over the heads wouldn't be better for cooling?

Interesting question. You may think so. But it's not that easy.
From one perspective more air over the heads would cool faster, I agreed but its not necessarily better.

One big problem is that the one place you don't want hot air condensing out water vapour into water droplets is inside the heads. That creates a steam engine for the simplistic answer and another two pages for the full answer.
No. Water vapour needs to be condensed out inside the cooling coils and then collected in the water separators where it causes the least problems and before it reaches the interstage stage head.

The two (2) other big considerations here to avoid are hydraulicing the heads, as condensed water pressure is not very forgiving or compressible, and work hardening the flexibility of the reed valves on the inlet and discharge valves by work hardening them by a process called quenching.

Now if you are over heating the pump the first thing is read the labels. Second how old is the pump.
Head temps on approach can be measured cheaply with an infra red gun (first spray a small patch of high temp matt black on the cooling coils to give accurate readings.

Granted you could open out the cooling by removing the belt guard (measure with and without the guard) but replacing the solid metal balance driven fully (drive end) will cause you more problems at this stage

Another good solution to consider is the cooling fan fitted to the pump
Is it a 4 blade, a 6 blade, or a UK built 8 blade
Again the blade angle is also a consideration on the UK builds they vary from the quite 0 degree pitch angle to the noisy 30 degree pitch due to it "cutting" more air per RPM revolution.
Not withstanding the location of the compressor and any additional noise considerations, human factor considerations and any legal or statutory obligation of a non military application. Iain