Used coltri mch6 portable infos!

[SurfLung]

My Used MCH-6
- The engine originally had some trouble getting fuel due to a rusted up and crudded up gas tank. This is a first run test of the engine after cleanup of the gas tank and fuel screens. Also first test of the compressor. Moisture accumulator and filter drains were spitting out quite a bit of moisture and foamy oil-gunk at first. I test filled this old Scuba cylinder several times. First time at 2.9 cfm. Later as the compressor began to work itself in, I filled several times at up to 3.5 cfm. That's a good-n-fast fill rate and the scuba cylinder was HOT when full.
- I changed the oil. And after some more run-time, the drainage from the moisture accumulator has become less and less mucky. It is now spraying out a watery mist with a thin film of oil. The drainage from the filter spigot has become almost totally dry. I am very happy with this compressor.

 

[RayfromTX]

The breathing air intake is a couple of feet from your engine exhaust. Take steps to avoid intaking the exhaust, filter for CO and by all means, test for CO on every tank.

 

[happy-diver]

Do this portable compressor really work? Sorry for my naive question, but if they are cheap and easily transportable, and they work fine, I would expect them to replace the bigger and more expensive ones, provided many diving centers are also in places not easy to access...Moreover, the price for filling the tanks, especially in the Maldives and other similar destinations, is so high it would make them very competitive. There must be something I am missing, or otherwise they are not really comparable in terms of quality

Coltri is good

Bigger means more air for less wear, faster
with automatic features in a relatively quiet box

but when the manufacturer sells you more air with the same pump by increasing revolutions
this is not so good

 

[tomfcrist]

The MCH6 is great. I’d suggest additional filtration on any small compressor though. I bought one a while back that had been sitting for a couple years. Tore it apart and rebuilt it for a couple hundred bucks. Works great. I don’t trust those tiny filters though, so I put it online with a bigger filter. Pumps OCA with ease.

 

[SurfLung]

Reply to RayfromTX - Not sure if I mentioned it but, My AERO did not come with a remote air intake hose. It's apparent that the previous owner used it without an extended hose. Then, I read the latest manual from Coltri Sub and it talks about "positioning" the compressor for adequate ventilation. The accessory "Remote Intake Hose" is only offered for situations where adequate ventilation cannot be achieved. I have never seen anyone operate a gas engine powered compressor without a Remote Intake Hose... But it got me wondering if it's okay to do it... Especially with my tendency to leave things original. Nobody offers a Remote Intake Hose kit... At least not on their webstores. Nuvair, MaxAir,... North Shore compressor, etc. On the other hand, the air filter that's on the AERO is also nearly impossible to find a new filter element for... So there's really no point in keeping it original. So I asked a friend about his MaxAir 35 and he said it came WITH the remote intake hose. He sent me a photo of the connection and it is nothing more than the internal mount for my intake filter, with the center drilled out and a hose clamped onto it. CRIPES! I've been running around looking for some clever plumbing solution. So, I will soon have a Remote Intake Hose to go along with my new BPR fill whip from Mr. 6000 PSI... And this little compressor will be ready for business!

Reply to happy diver - Yes I've heard the arguments about these smaller compressors running at high RPMs. I've come to the conclusion that if they are designed for the RPM that you are running them at, and you do the proper and regular maintenance, they seem to give reliable service for YEARS.

Reply to tomfcrist - Yes the little filter tube had me concerned at first. But even more of a concern was the lack of a Back Pressure Regulator or PMV to keep the filter pressure at 1800 psi or higher and give the best efficiency to the filter. In addition, this little AERO came with a filter cartridge that has nothing but charcoal in it... No moisture absorbing 13X sieve. I'm actually making solme major improvements by adding a back pressure regulator and using Filtertech see-thru filters with color changing test strips. These filters are 2/3rds 13X Sieve and the rest hopcolite (for CO conversion) and charcoal for tastes and smells. Furthermore, I can easily check the status of the filter... The top comes off easily and the filter pops up where I can lift it out and check the colored strip. Changing the filter is equally easy.
- Here's an interesting aside... On another compressor, I have a 4-tube filter array that came off an older version of the MCH-6... The Olmeva 6000... Uses the same filter tubes. But, it's much harder to get the filters out to check them. I have found that it is usually only the first filter that starts the test strip turning color. So maybe Aerotecnica figured to use a single filter tube and just make it a whole lot easier to check and change?

 

[rcontrera]

- Here's an interesting aside... On another compressor, I have a 4-tube filter array that came off an older version of the MCH-6... The Olmeva 6000... Uses the same filter tubes. But, it's much harder to get the filters out to check them. I have found that it is usually only the first filter that starts the test strip turning color. So maybe Aerotecnica figured to use a single filter tube and just make it a whole lot easier to check and change?

Olmeva and Coltri are two separate companies. They look similar but no relation.

 

[SurfLung]

Olmeva and Coltri are two separate companies. They look similar but no relation.

Good to know. Here's a photo of the Olmeva 6000 that got me thinking they were connected... Plus Coltri Sub sells to other private labelers like MaxAir.

- Note the same chassis and same 4 stage pump layout.
- Oil fill and air intake are located the same, too.
- The 4 filter tubes in the back are what I bought 2nd hand to add filtration to my RIX SA3. They use the same filters as Coltri/ MaxAir

 

[rcontrera]

Oh ... that is an oldie! They have square-ish filter housings now. But the European compressor industry is pretty incestuous in that they all seem to buy and sell to each other. I had ordered some Bauer valves for a customer and when they came in, they were exactly the same as the ones I had in my Coltri inventory.

 

[SurfLung]

Latest Developments...
1. My Briggs and Stratton engine is now running perfectly. As mentioned before, the gas tank was rusted and crudded up pretty bad inside. After cleaning the tank and intake screens, it started up and ran OK. After running more and more, it starts up real easy now. 1-2 pulls with the choke on gets it started and a quick push in of the choke and she takes off for as long as the fuel lasts. I think running fresh fuel thru it has probably dissolved the internal varnish deposits from the old gas. Lately I'm running premium gas with no ethanol or AVGAS... These can stand storage without going bad.
2. Made Up my Extended Intake Hose... What a relief! I can quit worrying about whether I should or shouldn't. I now have AT LEAST as good separation of exhaust and intake as other gas engine powered compressors. I put a brand new Solberg 8 cfm filter on it with 20 micron polyester filter media. Test sucked through it and there's literally no resistance. And of course, I'll have it positioned upwind of the exhaust.

3. Filtration Realities - I have a Back Pressure Regulator coming that will improve moisture condensation and filter efficiency. But right now this compressor goes through 13X sieve pretty fast. I have a Lawrence Factor cartridge in it that has 2/3rds 13X sieve and 1/3 Hopcolite and Charcoal. I think I have filled my 38 cf test tank 4-6 times on the filter and the indicator strip is already starting to turn pink. Hoping the BPR improves filter efficiency by a lot. The current Coltri manual says these filters should last 20-30 hours at 68-86 degrees Farenheit. On the other hand, this is a portable compressor... Designed for the convenience of filling scuba tanks at any remote location. I can certainly buy and bring more filters or cut costs by re-packing my own... If I end up using it extensively. As mentioned previously, the clear pre-pack filter with indicator strip is super easy to check and replace.

 

[rcontrera]

You can also blow down your separator more often. I ignore the manual saying 15 minutes and blow down at about 5 minutes and that has helped a lot.