MCH6 Filter lifetime

[Peter_C]

How many tanks a month do you plan on filling?

The price difference from the 16" to 32" housing is only $50 from the link above, and the larger one will work much better. You might find one for a reasonable price if you keep your eyes open. Watch ebay too and use an automatic bidder.

I really wouldn't consider a personal filter good enough for repeated use. Probably cheaper to replace the main filter more often.

 

[h90]

How many tanks a month do you plan on filling?

The price difference from the 16" to 32" housing is only $50 from the link above, and the larger one will work much better. You might find one for a reasonable price if you keep your eyes open. Watch ebay too and use an automatic bidder.

I really wouldn't consider a personal filter good enough for repeated use. Probably cheaper to replace the main filter more often.

In my understanding the personal filter is the same or almost the same size as the main filter I have installed. To repack the filter costs anyway nothing, I just worry that with the short filter life it is possible to accidentally get some moisture in my steel tank which than rusts without me knowing. Oil is less a concern...Oil in the air is pretty common in Thailand, you smell it and I think you need to clean the tank.
It would simply double the filter material I have.
My problem with getting a cheap one on Ebay is that I am in Thailand, so I have 1 shipping inside USA, one to Thailand and the customs.
With this from UK, I can send it together with my regular seafreights.....

 

[rcontrera]

The ColtriSub personal filter is exactly the same housing as the filter on the MCH6 and holds the same cartridge. The housing, top cap, bottom cap, o-rings and spring run around $250 and there are three holes ... inlet, outlet and drain ...
all in the chamber housing.

And the tall chamber is overkill big time since it is rated for 26000 cubic feet which works out to filling one tank a day for a year. And if you dive that much, you should really get a compressor that is rated for continuous duty.

 

[h90]

The ColtriSub personal filter is exactly the same housing as the filter on the MCH6 and holds the same cartridge. The housing, top cap, bottom cap, o-rings and spring run around $250 and there are three holes ... inlet, outlet and drain ...
all in the chamber housing.

And the tall chamber is overkill big time since it is rated for 26000 cubic feet which works out to filling one tank a day for a year. And if you dive that much, you should really get a compressor that is rated for continuous duty.

My estimate is 2-4 tanks a month, so I'll add a cheap personal filter, and do the filter change like there wouldn't be an additional filter so I am on the safe side.

 

[oxyhacker]

There's a company in the UK, Undersea Ltd or something similar, that makes a personal filter that takes the Coltri cartridge. They have a lot of other good hardware too.
I sure wouldn't go with a long stack. Takes too long to pressurize each time, and you either have to change the cartridges by calender, and throw away a lot of unused capacity, or run them several years, which is not a good idea either.
That's why I like my little accumulator - it holds a lot more than the little Coltri or Bauer filters, but is still a bit smaller than the short generic stacks.

With your fill volume, I would probably just replace the Coltri cartidge more often, rather spend good money on buying a second too-small filter, and keep my eyes open for a deal in something larger. BTW one nice thing about dealing with individuals on ebay rather than companies is that if you ask them nicely they will often mail stuff to you marking as "gift" or with neglible value. Not sure how Thailand works in this regard, but I've never had trouble mailing stuff there.

Oh, have you checked out Sheldon Sporting Goods? He was selling the accumlators already to install. Think he is out, but he may have something else.

 

[rjack321]

And the tall chamber is overkill big time since it is rated for 26000 cubic feet which works out to filling one tank a day for a year. And if you dive that much, you should really get a compressor that is rated for continuous duty.

For my consumption I have found the 13,000cf 16-18" to be perfect. I run about 75-80hrs/year on my Alkins which at 3.5cfm is roughly 16,000cf. So replacing the $45 secondary filter every 8 months is a good balance between using it up, having some reserve, and not having it open slowly "expiring" for a questionable length of time.

I have to shake my head at people putting 52000cf of filteration on a Bauer Junior or MCH6 :shocked2:

 

[Peter_C]

My estimate is 2-4 tanks a month, so I'll add a cheap personal filter, and do the filter change like there wouldn't be an additional filter so I am on the safe side.

Okay, so I stand corrected. 2-4 tanks a month is nothing. Dollar wise changing your current filter is probably the most cost effective.

On that note though, since when is overkill ever a bad thing?

For my consumption I have found the 13,000cf 16-18" to be perfect. I run about 75-80hrs/year on my Alkins which at 3.5cfm is roughly 16,000cf.

My compressor sees about the same amount of hours each year, but I have a 10cfm. ROI was there for me within a couple of years. Now it is simply convenience and savings. IE: my buddy shows up Saturday and says he is low in one of his tanks. We top it up in a matter of two minutes and head out to the ocean. Upon return we fill his tanks and send him on his way home. Super convenient. My friends purchase the consumables so there is no profit or money being exchanged on my end. Other than my dive buddies, I do not fill tanks as there is some liability with 32%. Hopefully we do not have any dive accidents.

 

[rjack321]

On that note though, since when is overkill ever a bad thing?

When your filteration is the same size as the tank you're filling that a bit of a problem. Especially if you are using the compressor as a trash bag booster or to occasionally pump 100% helium like me.

LF recommends changing their filters every six months regardless of use. So if you have massive quantities of filtration on a tiny compressor you throw away most of it unused. Prepacked filters are not cheap. Even media adds up if you are just tossing it unused.

 

[Peter_C]

When your filteration is the same size as the tank you're filling that a bit of a problem. Especially if you are using the compressor as a trash bag booster or to occasionally pump 100% helium like me.

By trash bag booster are you referring to pumping argon with your compressor using a trash bag over the inlet hose of the compressor then feathering the donor argon bottle to keep the bag slightly inflated? Wouldn't you also bypass any external filtration?

From what I understand pumping 100% helium is really bad for a compressor? Or are you only doing it for a couple minutes to top up with HE?

There is still nothing wrong with overkill, other than sometimes cost (Other times overkill is cheaper). I like the words industrial, heavy duty, and commercial. Often I push my shop equipment to those limits.

 

[rjack321]

My "trash bag booster" is a wine cork with a tube through it and a vegetable bag on the end. The cork goes in the compressor filter inlet. Gas is supplied to the mixing stick below (which is just a tube in this application doing no mixing) via the same regulators I use for continuous blending trimix or nitrox. As long as the bag is partially inflated the compressor is operating at ambient pressure. Its used to recycle or boost breathing gas, not for argon.

Bypassing your filters to pump argon or any other gas is risky business, you will oil the cr@p out of your whips completely contaminating them for breathing gases. Better to run all your gases through all your filters and keep the downstream piping as clean as possible. I just disassembled my whips and manifold after 5 yrs of use to clean them and its a pita and easy to procrastinate. Whips can and have ignited in the past though.

Assuming its delivered at ambient pressure, trimix up to 100% helium is not really a problem in an oil lubed compressor. There's a fair amount of blow by and some minimal foaming of the oil due to that blowby (I use chemlube 751). But helium doesn't heat up at all so the compressor runs alot cooler than you'd expect from the blowby. Michael Fisch on TDS talked me into trying it. They pump helium at the gas plant afterall...

I have been doing so off and on for at least 4 years. I wouldn't go above 200bar to avoid the increasing amounts of blowby, oil foaming and potential reduction in lubrication efficiency, but at lower pressures it works fine. I've probably pumped 8,000cf of 100% helium and 40,000cf of trimix through my Alkins over the past 5 years.

The key (for any gas or gas mixture) is to run at the lowest pressures possible and as Ray mentions to avoid sustained high pressure running. IMHO "high pressure" is anything over 3000psi. Below that you can hear the compressor working less and output is slightly improved (due to reduced blow by).