hydraulic accumulator filter

[h90]

Just a little info for reference ... on an MCH6, we put a priority valve and get about 3000-3300 cubic feet of air out of a filter cartridge. I get anywhere from 25-40 fills on a standard 80 depending on the time of year before I have to change the cartridge.

Thanks! I actually bought the priority valve from you! Works perfect and I can recommend to buy from rcontrera...I had a couple of questions and all where answered very fast and exactly.....So I am your cheerleader
Question: how high would you set it...ambient temperature is 35-40 degree (before I moved it sometimes into an aircon room). 100 bar? Or higher?
Someone told me to not let the MCH-6 in heat run for a long time continuously. So I stop after 30 min and let it rest a bit. But on the other hand I am not sure if it is good to stop and start all the time.

 

[rcontrera]

So I am your cheerleader

GREAT!! You gonna post a picture of yourself in your cheerleader uniform?

The small priority valves that we normally put on the MCH6 is not adjustable and comes set for about 1800 psi from the factory. For the adjustable ones, I suggest going up to 2000-2500 psi for best efficiency.

As for heat, if it gets hot enough to burn your hand by touching the 3rd stage outlet tubing, shut it down and let it cool. The continuous duty rating that this lacks has more to do with the size of tanks you are pumping than with the temperature that it is running.
All of today's small portables are made with lighter weight crank shafts and bearings to cut down on cost and weight. So sustained high pressure causes a LOT of stress on the parts and a premature end of life.

 

[h90]

GREAT!! You gonna post a picture of yourself in your cheerleader uniform?

The small priority valves that we normally put on the MCH6 is not adjustable and comes set for about 1800 psi from the factory. For the adjustable ones, I suggest going up to 2000-2500 psi for best efficiency.

As for heat, if it gets hot enough to burn your hand by touching the 3rd stage outlet tubing, shut it down and let it cool. The continuous duty rating that this lacks has more to do with the size of tanks you are pumping than with the temperature that it is running.
All of today's small portables are made with lighter weight crank shafts and bearings to cut down on cost and weight. So sustained high pressure causes a LOT of stress on the parts and a premature end of life.

Well I doubt you want to see that.....it might even dangerous to the younger forum members

yes I have the adjustable one....I had it set less than that....so I'll increase it.
Thanks for the information.

 

[iain/hsm]

Can I suggest you don't try using a hydraulic accumulator and leave it at that.

But suggest you try your BPR at each of the pressure settings options 1500, 1800, 2000, and 2500 psi just to see what little difference it makes in extending the life of the small chemical filter cartridge fitted on the Coltri MCH-6 using it in >30C hot climates. While not having a BPR fitted makes some loss in efficiency it is so small a difference in high ambients I cant agree that the higher the BPR pressure setting the greater the efficiency apart from a marginal difference in cooler climates.

While I agree that the higher the BPR setting the greater the mechanical water condensate separation potential but with the Coltri its so inefficient as to make much difference. Further running the pump continuously at 2500 psi rather than a more conservative 1500 psi make a greater difference in component life expectancy and bearing life so much so that the cost of a rebuild offsets the marginal improvement in filter life. To my mind the balance lays nearer the 1500psi mark than the 2500

Incidentally Bauer pull the same stunt on the Junior II and P100 to claim as long a filter life as possible by jacking the BPR setting to 3000psi and running the pump "full pelt". I guess from the sales and marketing position filter life is a selling point and the subsequent increase in service maintenance and repair costs is a bonus. Sadly with a customer base that knows only what the adverts told them, an extended filter life is a selling feature, the efficiency of which is lost. Iain

 

[h90]

I consider making a cooler....just tube bent in a coil with a small fan (size like in a computer), or in a way that I can put the coil in a bucket with water. On the other hand refilling filter isn't much work.
I also look out to find an old bigger separator or filter housing. I had the idea to just machine one from nice stainless steel.
But currently I have so much work, that I don't have time to go diving....so all the playing around with the compressor gets a bit ridiculous. It would be smarter to let it as it is and go diving instead.

 

[iain/hsm]

Good point on the cooling coil in a bucket of water but only downstream of the compressor final stage before the chemical filter.

But again you have this diminishing return with these small HP pumps, don't get me wrong a BPR should be factory fitted item but I can see Colri's reason for not fitting one, price is one reason and the operator can easy mimic a BPR valve by controlling back pressure using the tank filling knob up to say 100 bar 1500psi when filling from empty then opening the knob all the way after reaching say the 100 bar equalisation mark.

Cooling also can manifest other problems if you go for additional interstage cooling, with water condensing on the backside of the the discharge valve, causing cavitation pitting and seat damage rather than condensing in the cooling coils. The trick is to get the water condensing out in the tubes. Its too late by the time it gets to the separators, thats why the coil in a bucket is such a good point, but the bigger the separator the longer the dwell but also the longer the pulse so a bigger separator is no way as good an idea as say a bigger diameter chemical filter cartridge.

As long as the separator drains often enough and water condensing on the inlet stage valve doesn't end up hydraulicing the head off or the valve plates. Probably not a problem in hot climates and pumping air but you also should consider that you cant make the interstage cooling coils any length you like without also considering pressure drop, approach temp, and wetted coil volume. Iain

 

[h90]

But again you have this diminishing return with these small HP pumps, don't get me wrong a BPR should be factory fitted item but I can see Colri's reason for not fitting one, price is one reason and the operator can easy mimic a BPR valve by controlling back pressure using the tank filling knob up to say 100 bar 1500psi when filling from empty then opening the knob all the way after reaching say the 100 bar equalisation mark.

I dispute that theory. Well you are sure right with the price. But this compressor (300 bar version) is fitted with a hose without bleeding valve. So there is no bleeding at all (unless you consider bleeding it off on the water separator valve). So how does Coltri thinks you can screw out the 300 bar DIN under pressure and how many times the Oring will survive that?

I think they just left out everything that costs money without thinking anything :whacky:.

A cheap non adjustable BPR would have cost less than 5 USD mass produced. Drilling a hole + thread to make it a bleeding valve at the same time would maybe make a total of 7 USD maybe less but for sure less than 10 USD.
Not worth to save money there....or at least they could offer the compressor cheap and such an upgrade for 40 USD.
Specially the no bleeding valve is a very strange decision

 

[rcontrera]

I agree completely. When we get them in, we pull out the filter cartridge and put in the US version, install a priority valve and change out the filler fitting with one that has a shut off and bleed valve.

 

[iain/hsm]

You cant dispute the theory, that "theory" is a common practice LOL Well it is with us lot over here, goodness knows what you lot do, still calling an adjustable spanner a crescent wrench I guess. But like it or not Coltri sell the compressor with Heinz variety of charging (cylinder/tank connections) not their fault if the USA importer buys it in with the cheapest of cheap option the bare A clamp

Yes at the separator, that's exactly where you drain the compressor, but before shutting down, Its in the manual (I think from memory) something like "When full, close the cylinder/ tank pillar valve, open the separator knob to clear condensate and drain system, switch off power, then when fully drained you can open the A clamp or DIN fitting.

Granted it kills filter chemical life but thats not something customers of the MCH 6 are really likely to understand or care about most are happy with a 10 hour filter life. They don't know any different than it's cheap. Adding an aftermarket BRP also requires a bleeder downstream as the BPR as it too acts as a non return valve so bang goes using the separator drain to clear the charging line. Further most fitting in Europe are DIN and a small bleeder is fitted already to the DIN charging assembly.

So no need to try and screw out the DIN assembly at 300 bar you cant, besides the O-ring is cheap nitrile with more carbon black in it than a Polish Coal mine, replacing it every week/fill would in my book be an improvement Granted they left everything out that cost money, that's the whole point, but customer driven from the bottom up it's all about price.

The Coltri MCH-6 is the cheapest scuba compressor and has the cheapest components fitted to the absolute minimum, why should this be a surprise. Any more than some clown trying to sell hydraulic accumulators passing them off as scuba filters? All relay on one factor…. the ignorance of the customer

Now assuming you didn't miss out the zero if you can find anyone to make a BPR for 5 USD at the pricing your quoting I will buy a 200 of each colour and Ron I guess will double it. Iain

 

[iain/hsm]

I agree completely. When we get them in, we pull out the filter cartridge and put in the US version, install a priority valve and change out the filler fitting with one that has a shut off and bleed valve.

Ray, I understand why the mod you do here, I'm guessing an AE inline BPR plus bleeder but whats this US version filter cartridge? an LF?
Just to confirm same Coltri filter shell, you just replace the cartridge? Can I ask why. Iain