Coltri MCH6 runtime

[VikingDives]

I'm considering purchasing an MCH6. Reading the manual it says that they aren't for continuous use, but I can't find anything that says how that's defined. Am I missing something, or is there some general rule of thumb that I'm ignorant of?

 

[Curious_George]

That’s what I use. I think you are supposed to let it cool off between tanks, and it will be cool to the touch in about 10 minutes. One of my dive buddies was filling doubles all the time with his and ended up going back to the factory for work after a couple years, out of warranty.

Fills take 20-25 minutes depending on how empty and size of tank. Be super careful if you get the gas one. I’ve had a few times where the wind switched directions and found some CO in a tank. But I guess that’s true of any gas compressor.

 

[happy-diver]

With such an investment perhaps you could take some more time to organise some more shekels
for something less finicky that's not going to give you the sh@@ts for the rest of your pumping life

 

[iain/hsm]

I'm considering purchasing an MCH6. Reading the manual it says that they aren't for continuous use, but I can't find anything that says how that's defined. Am I missing something, or is there some general rule of thumb that I'm ignorant of?

Recreational sports scuba compressors have no defined "use" hence the lack of written definition.
Used in this context it is subject to your opinion and "you" the end users "feelings"

This is why also you only hear and are led to believe the 40% nitrox rule but will never see it in writing from manufacturers or if in the rare occations you do on a new air compressor it is it is always subject to very heavy "user conditions" such as used only in conjunction with a cheap membrane tube.

Also why you will never hear what the test percentage is used above the 40% maximum so called "rule"

Now ask yourself the question if your compressor runs for say 30 minutes filling a cylinder how much "hotter" does it get when filling two, or four of six. The answer is it doesen't but the real reason for this intermittent use condition is because of poor design, weak components and running it peddle to the metal.

This is to enabe the re sellers, dive shops etc to answer the single most asked question by folk considering buying a new compressor. And the single number one question is ............ "How long does it take to fill a tank." with the number two question being how much does it cost.

 

[rob.mwpropane]

Recreational sports scuba compressors have no defined "use" hence the lack of written definition.
Used in this context it is subject to your opinion and "you" the end users "feelings"

This is why also you only hear and are led to believe the 40% nitrox rule but will never see it in writing from manufacturers or if in the rare occations you do on a new air compressor it is it is always subject to very heavy "user conditions" such as used only in conjunction with a cheap membrane tube.

Also why you will never hear what the test percentage is used above the 40% maximum so called "rule"

Now ask yourself the question if your compressor runs for say 30 minutes filling a cylinder how much "hotter" does it get when filling two, or four of six. The answer is it doesen't but the real reason for this intermittent use condition is because of poor design, weak components and running it peddle to the metal.

This is to enabe the re sellers, dive shops etc to answer the single most asked question by folk considering buying a new compressor. And the single number one question is ............ "How long does it take to fill a tank." with the number two question being how much does it cost.

So what's the "rule" for highest mix that's ok in a compressor, from your perspective?

edit: should better ask what are they tested at, and what do you feel comfortable doing?

 

[iain/hsm]

So what's the "rule" for highest mix that's ok in a compressor, from your perspective?

edit: should better ask what are they tested at, and what do you feel comfortable doing?

That's easy: Read the label.

Rule 1. If it say Air Compressor on the compressor label or data plate then it's 21% Atmospheric air.

Rule 2. And the answer to your second question. If the label or data plate reads Compressed Air or Breathing Air compressor they are not tested above 21%

Rule 3. If in doubt refer to Rule 1

There is no 40% rule its bull for the ignorant. Coltri as others know this perfectly well.

 

[iain/hsm]

and what do you feel comfortable doing?

Now to answer your second question.
1. On that Coltri 21% Air only

But by way of example for a proper nitrox compressor. Years ago when I was young and fit I found myself reporting at the Navy Dockyard Haifa Navy Base to a little known unit known as YALTAM known for its gentle art of underwater swimming and admiring fish. YALTAM is a bit like being a PADI diver but doing only try dives in a pool.

The task of the day was to play with the new nitrox compressor and commision it.
It worked OK once a few issues had been sorted but the oxygen regulator was a simple cheap welding type single stage regulator connected to a big bank of high pressure oxygen cylinders.

In order to "test it" Mil-Spec fashion I wondered how a cheap single stage regulator would perform once it reached the lower pressures in the bank. P1 V1 against P2 V2 for the maths. So I left it running at 40% and went to the canteen for lunch. After lunch the original set point of 40% had increased as the oxygen supply bank pressure decreased.

At the point when the discharge percentage had reached 73% others in the group thought it best that we stop "testing it" and simply recommend using a better more expensive Tescom 1300 two stage regulator to avoid the percentage creep as P1 decreased and V1 increased.

It was a 30 cfm 5000psi 4 stage nitrox compresor certified for 50% now tested to 73% in tru "Mil-Spec" fashion.
I leave it to others to do what they feel confortable with, as for myself I feel comfortable trusting only in God but verifying everything and everyone else.

 

[Edward3c]

I'm considering purchasing an MCH6. Reading the manual it says that they aren't for continuous use, but I can't find anything that says how that's defined. Am I missing something, or is there some general rule of thumb that I'm ignorant of?

I often run mine for 2 or 3 hours only stopping it to refuel, filling up to 10 tanks some to 300bar.

 

[VikingDives]

@Curious_George @Edward3c Thanks. Anything you wish you'd known or done differently? Would you buy another one? How many hours have you put into yours?

 

[Edward3c]

First thing I did with mine was change the rubber feet for caster wheels with a locking mechanism. Makes moving it round so much easier.

From June to October last year I was out twice a week, often took the compressor and pumped during the surface interval. Its nice an compact and sits nicely in the back of my SUV.

I might get an auto-drainer fitted, but only if I get really lazy.

Hoping to get out next week, now we are alowed to travel outside the county.