Nautica MCH-6 question

[khadux]

Is the Nautica MCH-6 another re-labeled Coltri MCH-6? Is the Nautica MCH-6 setup to handle 4500 psi fill duty? Thanks.

 

[veriqster]

yes, it's a coltri block; depends how you define "full duty", if you mean turning it on and pumping it up0 to 4500psi than it will do, if you think filling cascade tanks than i would look for something different.
p.s. following is a quotation from a forum which shows up on the first page if googling for "nautica mch-6"
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EvilDavy14
08-03-2006, 06:48 PM

That compressor is sold now as a Max-Air, Nuvair (EZ Air). It is a 3.5 cfm 4500 psi compressor. It was designed to fill scubas to 3000 PSI in about 20 minutes. It is limited to 20-30 minutes of run time. Not really designed to fill bulk tanks. I personally feel it is too small for ANY field. It would be ideal for a traveling scenario team.

jjk454ss
08-04-2006, 10:03 AM

That is kind of what it was starting to sound like to me. I am not filling tanks very often, like I said 2 tanks once or twice a week. The only thing I didn't see before though was that it is limited to 20-30 minutes of run time, why is that? Do they overheat or what?

EvilDavy14
08-05-2006, 12:44 PM

Yes, they over-heat. Once damaged, they cost about $1000 to fix. All the small compressors were designed to support a single scuba diver. 20 minute run times. The one exception may be the Alkin. They claim there is no run time limitation. I believe them but I think it is because they are made in Turkey with a lot looser specks than the Italian or German compressors. That MCH6 would be great for you and a few friends. If you fill large tanks, you would have to do it a little at a time until they are full and just keep them topped off. By the way, it will take a little over 2 hours to fill a large tank to 4500 PSI with that guy. Running it half the time, 4 hours. Dividing it into thirds would be better, so 6 hours. You said 2 of them? 12 hours.
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p.p.s. sorry if it sounds mean

 

[rjack321]

While most small compressors can get to 4500psi, those kinds of pressures really accelerate the wear & tear on them. No small compressor currently available is suitable for continuous duty (more than 1 or 2 hours at a runtime) especially not at 3000+psi.

 

[rcontrera]

Nautica was an early importer of the Coltri MCH6 line of compressors. I don't know when they closed their doors, but it has been quite a while. There are still about 22 different distributors that either market Coltri products with their own stickers on them or use Coltri compressor blocks in their own packaging. I think I am the only one, other than Coltri themselves, selling under the Coltri brand.

In order to keep the costs and weight down on the small compressors (MCH6 and JR II), the manufacturers cut down on the size and heft of the crank and bearings. The little guys are not designed for the sustained stresses of high pressure ... like filling bulk bottles.

However, they can fill 4500 psi small bottles (like paintball cylinders) all day long as long as they are being cycled (fill one, drop pressure, fill another, drop pressure, etc.)

As for heat, I was able to run an MCH6 for several hours filling 80s and 72s without hitting max temp (can't hold your hand on the outlet of the 3rd stage ... about 135 degrees). Of course, it was a cool 65 degrees or so in our great Northwest.

 

[oxyhacker]

I had a Nautica-branded MCH6 for a couple years. A compressor shop that sold them then told me they usually blew up early, or lasted forever. Mine apparently was one of the latter. They only claimed 3000 psi or so then, not sure when they started listing them as good for 4500. And hard to say what changes they may have made - Bauer used to make 3200 and 4500 psi versions of the same compressor, and there would be significant differences between them, the most important probably being separator and media stacks designed for the higher pressure.

My understanding is that there have been a number of improvements on the MCH6s over the years, both in the parts, and in the quality of materials and machining, so you can't assume yours has the same capacities as a new one - especially considering it probably has a fair bit of hours on it by now.

If you want to get the answer straight from the horse's mouth, email Claudio Coltri at Coltri in Italy and ask him, he is usually very good about responding.

 

[rcontrera]

Thanks for catching that, Vance.

Yes, the Nautica was rated for 3000 and was an older version of the MCH6. I was babbling there and went on about current capabilities and totaly missed the OP asking if his old compressor could do 4500 psi.

 

[khadux]

You folks are a wealth of knowledge here!

Now, the Nautica is rated for 3000 psi but do have the same block as the current Coltri MCH6, would I put too much stress on the compressor if I fill SCBA tank 88cf to 4500 psi? Probably 3 times a week.

 

[rcontrera]

That's really a tough one. They redesigned the MCH6 a few years before I shifted over to them from Bauer and I have been told that bearings, crank and cylinders are all different.

If it says 3000, stick with 3000 to be safe.

 

[oxyhacker]

No one can answer that question without knowing the history of that particular compressor - and your tolerance for risk.

You folks are a wealth of knowledge here!

Now, the Nautica is rated for 3000 psi but do have the same block as the current Coltri MCH6, would I put too much stress on the compressor if I fill SCBA tank 88cf to 4500 psi? Probably 3 times a week.

 

[khadux]

That's really a tough one. They redesigned the MCH6 a few years before I shifted over to them from Bauer and I have been told that bearings, crank and cylinders are all different.

If it says 3000, stick with 3000 to be safe.

Ray and everyone, thanks. I'll stick with the rated pressure.