Onboard Nitrox System

[padimanatee]

We have a new 60' aluminum expedition sail / dive boat and request advice for an onboard nitrox system. We wish to avoid carrying oxygen cylinders. We purchased a Bauer Mariner (now for sale) as I understand newer systems would be a better and safer option. We have an 8 kw diesel gen set and lots of room. Six divers max. but some locations will be remote.

 

[rjack321]

Keep the mariner.

Power the mariner via its own diesel power, 8kw won't do it along with all your other power needs (like A/C & reefers)

Carry gaseous O2, or if you can find a supplier and cope with the evaporative loses a dewar of liquid O2.
One 240cf O2 bottle via continuous blending will make 1700cf of EAN32. Scale up or down as needed.

The 2nd compressor needs + filtration for a membrane system are not really practicable for a 60ft sailboat. Even the Nautilus Explorer - a vessel 2x your size is not using a membrane system.

 

[CraigAClark]

In order to start a Mariner (which is standardly a 7.5 hp electric motor), your genset would require a minimum of 25Kw, straight up. Not sure how low you could get with a frequency drive, but not 8kw, which would start a 3 hp. Even a Capitano is going to require 20Kw, straight up. The only Nitrox production that doesn't require O2 is the membrane. If you can figure out how to drive that Mariner outside the engine/generator room, there is a way to supply air to the membrane without an L.P. compressor. Mind you, it is pretty taxing on your Mariner, but if you have no other choice........

Craig

 

[rjack321]

Belt driving the mariner off the main engine might work (depending on size of main). But its hot and dirty in an engine room and I would want a better ventilated, larger(?) cooler space to avoid overheating the compessor oil.

Not sure what the 'safety' concern is, but a Rix is not going to run any cooler in that environment. And you'll still need fresh clean input air + filtration.

 

[veriqster]

or get your hands on a Kidde or Noah-Howden that are designed to operate inside an engine room compartment (in a tank) and just plumb the intake and output. plenty of options but none will be cheap (custom install) and all will require a LOT of work and research.
p.s. The best guuy to talk to about Kidde or Howden units is Jim and shelden sporting goods, i think he's out of Howdens though.

 

[padimanatee]

Thank you to all who replied. We purchased a Bauer Mariner compressor from a shop in central florida which rebuilds and designs scuba compressor systems. When we picked up the compressor, it had a warning tag which stated the compressor could not be used for Nitrox. While we were waiting for the compressor, we bought a new Hatz diesel as we knew the gen set would not provide the inrush power for the electric motor which came with the Bauer. I have all this equipment for sale for far less than I paid for it, because I understand it cannot compress nitrox.
We could carry oxygen onboard and we could blend. We have lots of room. The boat was designed with an aft dive room. I think, based on the tag on the Bauer, that we bought the wrong compressor. It seems a nice compressor for air divers.
We posted to get some real advice on working systems so we won't make another mistake.
Anyway, again my thanks to all as this is a great board and we wish we had found it earlier.

 

[DennisS]

Have you looked at the Nuvair systems

Nuvair - Nitrox System | Nitrox Compressor | Nitrox Solution | Dive Shop Package | Nitrox membrane

 

[padimanatee]

Yes! and I'm impressed. I'd like to get in touch with owners of the system. We also thought about using aluminum cylinders for the oxygen. We own two for argon for aluminum welding, and while they don't hold as much gas, they are a lot easier to lift.
We have friends (Divers Den in Georgia) who blend and they are pleased with the blending system.
I'm just not sure I fully understand the pros and cons of membrane vs blending.
Thanks again.

 

[DennisS]

I work with a research ship that has one onboard. You have to have a source of LP Air in addition to the HP comressor. It works good. The membrane system gets rid of O2 tanks. You have unlimited O2 and can pump up to 40% on a good day, realistically around 37-38%.

 

[padimanatee]

Thanks again. Just curious, but do you know why my Bauer Mariner can't pump nitrox? Is it because it's a Mariner 1?
Also did you guys get the whole system from Nuvair? Happy with them?