Buying a compressor

[Cheekymonkey]

Wow, how deafening are they then? The smaller ones I mean, will they make neighbors cry?

 

[rcontrera]

It is a 5.5 HP gasoline engine and the compressor is not all that loud. 87 decibels if that means anything to you. Kind of like a 6-7 HP gasoline driven lawn mower. Does your neighbor gripe when you cut the grass?

 

[pescador775]

Cheeky, don't neglect to take a look at the Alkin. Most of the portables are rated 3.5 cfm (FAD). Actual fill times are 24-26 minutes based on an empty S80, less in typical use as the cylinders may have retained some pressure. The pricey Oceanus is rated 4.1 cfm, similar to the Junior with larger first stage and oil sump.

 

[Cheekymonkey]

Yea I dont mind those slower fill times, but I'd be be worried about the noise factor, I'm quite close to my neighbors.

 

[Rogier]

If you want to start mixing gasses take a good look at the RIX compressors! These don't need oil not even filters! This will save you a lot of headache!

 

[oxyhacker]

compressor speed makes a big difference in how much noise they make. The little ones are all screaming along at preposterous rpms, and noisey as a result. The midsize ones run much slower and as a result quieter and cooler but are still small enough to take along if you need to. Unfortunately, the midsize ones are getting hard to find now that Bauer replaced the Utilis with the Oceanus and just about the only ones left are the little Alkin and the Capitano.

Re the Rix, Rix may produce clean air, but you run into the "Rix Paradox" - while the air is clean (no hydrocarbons) it is wet, and to get it dry enough to be suitable for steel tanks or cold water diving you need exactly the same sort of filtration as it takes to clean up the air from a oil lubed compressor. Which comes standard on the oil lubed compressor, but is $400-1000 extra for a Rix. And while the Rix doesn't need oil, it has to be greased every 20 hours or so with expensive, hard-to-find grease.

 

[Rogier]

Ah I did not know about the expensive lube on the Rix. Regarding the wet air. This can be solved with a home brew water seperator. Not to hard to do.
Low rpm is the key to trouble free compressor life indeed!
I had my K15's rigs with smaller pullies on the engine side in order to have below 800 rpm's. it made a mayor difference. Thrue its less CuFt per min. But its wel worth it!

 

[rcontrera]

Ah I did not know about the expensive lube on the Rix. Regarding the wet air. This can be solved with a home brew water seperator. Not to hard to do.

Yes, you can install a mechanical separator, but don't forget the chemical one as well. The mechanical separator just "beats" a bunch of the moisture out of the air but not the majority. Then, by going through Alumina or Molecular Sieve, it actually absorbs most of the remainder of the moisture. Since you don't have to worry about oil you may not need a CO scrubber anc could get by with only a desiccant tower. However, charcoal is only to "sweeten" the air and remove any residual odors so I would have that in my tower as well ...oil or no! Oh, and don't forget to put a pressure maintaining valve on the outlet of your filter cannister as well since the separator and chemicals work much better when the air is denser.

Low rpm is the key to trouble free compressor life indeed!
I had my K15's rigs with smaller pullies on the engine side in order to have below 800 rpm's. it made a mayor difference. Thrue its less CuFt per min. But its wel worth it!

Quite true! Coltri Sub uses that in their various models of compressors. Basically, they only have three compressor blocks ... the little one for personal sized machines, the mid sized for almost all the rest of the line and the new one that came out last year for their 6000 PSI monsters. They just rig them with different speeds and heads to get different capacities. You will see the small one advertised by lots of different distributors (MaxAir, American Eagle, SeacomAir, American Airworks, Northern Compressor, etc.) at varying outputs and that all depends on the speed of the machine. I have and electric single phase 115 VAC that runs the slowest and it is rated at 2.8 CFM. The same compressor run by the gasoline engine will put out 2.8 to 4.5 CFM depending on the throttle setting.

 

[iain/hsm]

Re the Rix, Rix may produce clean air, but you run into the "Rix Paradox" - while the air is clean (no hydrocarbons) it is wet, and to get it dry enough to be suitable for steel tanks or cold water diving you need exactly the same sort of filtration as it takes to clean up the air from a oil lubed compressor. Which comes standard on the oil lubed compressor, but is $400-1000 extra for a Rix. And while the Rix doesn't need oil, it has to be greased every 20 hours or so with expensive, hard-to-find grease.

Vance. The only "Paradox" is how you manage to get it so wrong. LoL.
The RIX grease is $27 for a 14 ounce tube. Using the supplied lever style grease gun dispencing 1.28 grams of grease per stroke and needing six shots every 25 hours for all three stages, thats what? At 0.035 ounces per gram, its 312 shots.
So this "expensive" RIX grease lasts you 52 services or 1300 hours running and costs $27. It doesnt get any simpler. Now work out the synthetic diester cost on your oil lube compressors with oil changes every 50 hours.

 

[oxyhacker]

No all that wrong. It might last a long time, but I think most of us would still consider $27 a tube expensive. And you won't find it at the local hardware or industrial supply when you run out, which means you have to order it direct from Rix. And Rix USA has a $100 minimum order! That's hardly a reason not to buy a Rix, but is something anyone trying to decide what compressor to buy ought to know. As they ought to know about the filter situation.

And OK, I said "20 hours or so" instead of 25 hours. I thought that was pretty close, for off the top of my head.

Vance. The only "Paradox" is how you manage to get it so wrong. LoL.