looking for compressor advice
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pescador775
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About preferences; these would be based on personal requirements or bias (how were you raised?). The RIX SA6 is fairly heavy but is lighter than a comparable Bauer. The RIX should make a fine fixed installation and also be transportable (different than "portable"). I consider it to be expensive but can be purchased on the surplus market for little money. It has the cache of being "sweet air" oiless in design.
The comparable Bauer Capitano results from almost continuous development and improvement dating back to 1946. It is quite heavy and barely transportable. However, when not abused, it will last a lifetime in personal use. It is expensive but available on the surplus market at a big discount.
If one is goosey and jumps at the sound of a balloon popping, the hammering and thumping of a Bauer are probably not for you. If one's preferences are to the security of knowing that your compressor is a rock solid investment, then the Bauer might be for you after all. If you are inattentive while mixing NITROX, and are iffy in a technical sense, then you should be aware that jolting the Bauer with pure O2 could send your compressor through the roof. In that case, the RIX could be preferential knowing that smoking that machine would probably not be as big a threat to your safety.
However, if one fails to understand the details, or is too focused on details, and does not always appreciate that compressed gases, all gases, are potentially dangerous. then you should not consider a compressor at all.
The comparable Bauer Capitano results from almost continuous development and improvement dating back to 1946. It is quite heavy and barely transportable. However, when not abused, it will last a lifetime in personal use. It is expensive but available on the surplus market at a big discount.
If one is goosey and jumps at the sound of a balloon popping, the hammering and thumping of a Bauer are probably not for you. If one's preferences are to the security of knowing that your compressor is a rock solid investment, then the Bauer might be for you after all. If you are inattentive while mixing NITROX, and are iffy in a technical sense, then you should be aware that jolting the Bauer with pure O2 could send your compressor through the roof. In that case, the RIX could be preferential knowing that smoking that machine would probably not be as big a threat to your safety.
However, if one fails to understand the details, or is too focused on details, and does not always appreciate that compressed gases, all gases, are potentially dangerous. then you should not consider a compressor at all.
As I understand it the enriched oxygen environment makes the compressor heads heat up beyond design and its the overheating that shortens the compressor life.
By comparison we fill literally thousands of tanks so we may have issues cropping up that more casual users may never see. Additionally much of our use is in more hostil environments (North Pole -40 degrees, Antarctica -65 degrees, Shipboard with extreme salt environment etc.)
our Rix compressor (usa version) simply runs much more dependably than what our Makos or Bauers or Max Aires do.
We interchange between gas and electrical depending upon where in the world we are using the compressors.
As for filtration we use Global filter towers with Lawrence Factor cartridges. It's less expensive if you pack your own filters however due to our expeditionary use its much easier to use the pre made cartridges.
I think the main thing you have to determine is realistically how many tanks you will be filling. If you are making say 100 dives a year and you are filling only your own tanks almost any compressor on the market will last a very long time. If others are benefiting from your compressor ownership I would suggest you make sure they have a financial investment in the unit even if it is only paying for fills.
By comparison we fill literally thousands of tanks so we may have issues cropping up that more casual users may never see. Additionally much of our use is in more hostil environments (North Pole -40 degrees, Antarctica -65 degrees, Shipboard with extreme salt environment etc.)
our Rix compressor (usa version) simply runs much more dependably than what our Makos or Bauers or Max Aires do.
We interchange between gas and electrical depending upon where in the world we are using the compressors.
As for filtration we use Global filter towers with Lawrence Factor cartridges. It's less expensive if you pack your own filters however due to our expeditionary use its much easier to use the pre made cartridges.
I think the main thing you have to determine is realistically how many tanks you will be filling. If you are making say 100 dives a year and you are filling only your own tanks almost any compressor on the market will last a very long time. If others are benefiting from your compressor ownership I would suggest you make sure they have a financial investment in the unit even if it is only paying for fills.
pescador775:
Thanks for the advice. If anything, at times I may get too focused on the details, however safety is always my first concern. Considering the investment, I want to understand all of the issues and make sure I purchase the best unit for my application. Right now my trimix instructor provides my trimix fills (custom built gas driven Bauer compressor), however I need some independence as well as portability. I can handle the basic mechanical issues, but would'nt feel comfortable tackling any major overhauls, and am definatively attentive when filling tanks with anything. I never considered the Rix seriously, but this thread has given me more to contemplate. I would likely be comparing the Bauer Oceanus vs the Rix SA-6.
pescador775
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Seadiver, I agree that the RIX would probably be the best choice for arctic environments. Just carry the usual spare parts for a RIX, third stage piston, etc.
The Bauer would require a low viscosity oil if the temps are less than 45F. In arctic temps this would be 5W (ISO 10). The only oil which I am familiar with that might do for this is Aircraft Instrument oil (Brayco 885). However, there will other problems with condensator freezing and freezing lines. For NITROX pumping at low temps, but not below 0F, you could use Ultrachem/Omnilube 32/46 (ISO 39). No spare parts should be needed. However, pack the usual oil and filter media.
The Bauer heads or valves do not "heat up" when pumping NITROX. That is nonsense. Carbon deposits may form on the valves and seats if oil is not changed more frequently with NITROX use. This is due to slow oxidation of the oil.
Dab, the RIX SA6 pumps about 5 cfm. The Oceanus puts out about 4 cfm. However, the Oceanus is MUCH lighter in weight. For personal use, I would pick the Oceanus. For a fixed installation dedicated to NITROX/mixed gas, the RIX is very competitive. It's a tossup. Mixing NITROX with a portable compressor is a hassle. You have to place the engine driven portable in an open space, move your oxygen cylinder and mixing stik close by, and make sure that wind does not carry exhaust into the stik. Having your compressor in a closed space with everything already set up is the way to go. This means electric power and weight of the compressor is less significant in the decision making. Still, if you like the idea of being able to move your compressor, like load it into your truck by yourself, the 100lb Bauer Oceanus electric would be a good choice.
I am original owner of a 1974 Capitano. Total hassle factor has been 2 change outs of the third stage valves (1 hour job) plus oil changes and filter maintenance. There is about 1500 hours on the machine.
I own two Kidde portables which I built in my shop and which can be seen on a couple of the SB threads.
The Bauer would require a low viscosity oil if the temps are less than 45F. In arctic temps this would be 5W (ISO 10). The only oil which I am familiar with that might do for this is Aircraft Instrument oil (Brayco 885). However, there will other problems with condensator freezing and freezing lines. For NITROX pumping at low temps, but not below 0F, you could use Ultrachem/Omnilube 32/46 (ISO 39). No spare parts should be needed. However, pack the usual oil and filter media.
The Bauer heads or valves do not "heat up" when pumping NITROX. That is nonsense. Carbon deposits may form on the valves and seats if oil is not changed more frequently with NITROX use. This is due to slow oxidation of the oil.
Dab, the RIX SA6 pumps about 5 cfm. The Oceanus puts out about 4 cfm. However, the Oceanus is MUCH lighter in weight. For personal use, I would pick the Oceanus. For a fixed installation dedicated to NITROX/mixed gas, the RIX is very competitive. It's a tossup. Mixing NITROX with a portable compressor is a hassle. You have to place the engine driven portable in an open space, move your oxygen cylinder and mixing stik close by, and make sure that wind does not carry exhaust into the stik. Having your compressor in a closed space with everything already set up is the way to go. This means electric power and weight of the compressor is less significant in the decision making. Still, if you like the idea of being able to move your compressor, like load it into your truck by yourself, the 100lb Bauer Oceanus electric would be a good choice.
I am original owner of a 1974 Capitano. Total hassle factor has been 2 change outs of the third stage valves (1 hour job) plus oil changes and filter maintenance. There is about 1500 hours on the machine.
I own two Kidde portables which I built in my shop and which can be seen on a couple of the SB threads.
A side note to air intake,
Shipboard we utilize a series of clear plastic 4 inch tubes that fit together end on end. at the top of the tube we install a pre-filter so the air in the tube is already fairly clean. At the bottom of the tube we connect the air inlet tube that leads to the compressor or stick. We can set up to 40+ feet of this tubing. What this allows is the flexibility of getting the air intake away from exhaust or gas fume sources. A similar system would work well for any portable compressor, In a campground you could attach the tube to a tree etc. helping to insure that no exhaust fumes from the engine gets into the compressor. The plastic tubing is a food grade material. I don't know if you could substitute Pvc for it or not...
Shipboard we utilize a series of clear plastic 4 inch tubes that fit together end on end. at the top of the tube we install a pre-filter so the air in the tube is already fairly clean. At the bottom of the tube we connect the air inlet tube that leads to the compressor or stick. We can set up to 40+ feet of this tubing. What this allows is the flexibility of getting the air intake away from exhaust or gas fume sources. A similar system would work well for any portable compressor, In a campground you could attach the tube to a tree etc. helping to insure that no exhaust fumes from the engine gets into the compressor. The plastic tubing is a food grade material. I don't know if you could substitute Pvc for it or not...
pescador775
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Food grade is nice but PVC is standard stuff for NITROX sticks and small intake "snorkels". I haven't heard any complaints. It is cheap and readily available. However, a "stik" is much shorter than the intake tube that you describe. If PVC should add any odor the compressor filter would sort it out. However, if one were to get really picky one could research whatever emissions are produced by PVC plastic and compare with an adsorbtion chart for charcoal. It is smart to use large diameter pipe for long extensions. The usual 1" tube which matches the some compressor intakes would cause significant restriction if longer than about ten feet.
A bit off topic, but one should be aware that pumping TRIMIX through a compressor can result in added heat. I assume this is due to the work necessary to process helium, a gas with rather low compressibility. I've heard from "tech" divers that the piston rings of the RIX don't last very long in this application. However, I also heard from somebody who has 150 hours on his RIX without a problem. I'm not aware of problems with the Bauer when pumping TRIMIX but every day is a learning process.
Pesky
A bit off topic, but one should be aware that pumping TRIMIX through a compressor can result in added heat. I assume this is due to the work necessary to process helium, a gas with rather low compressibility. I've heard from "tech" divers that the piston rings of the RIX don't last very long in this application. However, I also heard from somebody who has 150 hours on his RIX without a problem. I'm not aware of problems with the Bauer when pumping TRIMIX but every day is a learning process.
Pesky
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