K14 Elevated CO2

[CG43]

Everyone who says you have to drain the filter tower after each use doesn’t understand high pressure air filtration or needs to go back and read what Rob and Happy-Diver posted.

Take a look at the drawing in scuba engineer. We talked all the time about the last separator before the filter and it is located after the check valve in order to work well .


Of course, most compressors also have water separators between the stages, but not all .
Now Wallowa not only wants a dry filter, but also a compressor that is as dry as possible on the inside.
To achieve this, he opens the two available drain valves. There are no other valves because the MCH 6 has no water separators between the stages. This increases the amount of moisture in the compressor and the cooling lines and therefore makes it particularly advisable to do this cooling/drying procedure before each long period of non-use.
My suggestion on page 5 #49 was to only open the separator drain valve (fill hose closed) during this cool/dry procedure so that at least no moist air flows through the filter.

If the bauer company recommends cold starting petrol engines with an empty filter, the occasional build-up of pressure in the filter cannot be as catastrophic as some people here are telling us.
If you were abel to examine it closely, you might find that the additional amount of water that the filter receives when starting from low pressure to PMV pressure (PMV closed) corresponds to a running time of 20 minutes.

Anyone who knows more about this, I am interested.

 

[Wallowa]

Take a look at the drawing in scuba engineer. We talked all the time about the last separator before the filter and it is located after the check valve in order to work well .


Of course, most compressors also have water separators between the stages, but not all .
Now Wallowa not only wants a dry filter, but also a compressor that is as dry as possible on the inside.
To achieve this, he opens the two available drain valves. There are no other valves because the MCH 6 has no water separators between the stages. This increases the amount of moisture in the compressor and the cooling lines and therefore makes it particularly advisable to do this cooling/drying procedure before each long period of non-use.
My suggestion on page 5 #49 was to only open the separator drain valve (fill hose closed) during this cool/dry procedure so that at least no moist air flows through the filter.

If the bauer company recommends cold starting petrol engines with an empty filter, the occasional build-up of pressure in the filter cannot be as catastrophic as some people here are telling us.
If you were abel to examine it closely, you might find that the additional amount of water that the filter receives when starting from low pressure to PMV pressure (PMV closed) corresponds to a running time of 20 minutes.

Anyone who knows more about this, I am interested.

Thanks for recommendations...but I run the cooling/drying after the compressor has been through a duty cycle not "before each long period of non-use"...so that the compressor when not in use has the least moisture as possible in the cylinders while it sits idle....when I first start the compressor to reduce the load I leave both drains open for perhaps 60secs and perhaps that is what you are eluding to.

Did not know some compressors have separators between stages...how would this be plumbed? Can't envision how and where they would be place between cylinders.....how many drains would there be?

Good exchange of information and appreciated.

 

[Agro]

Did not know some compressors have separators between stages...how would this be plumbed? Can't envision how and where they would be place between cylinders.....how many drains would there be?

Every new compressor I know has at least one separator between stages. Unless Coltri of course.

I don't know every new compressor so there might be other cheap compressors without additional separator.

This separator between stages drains a lot of air/oil so it seems to be very necessary.

The larger Coltris of course have a 2nd separator. No professional user would buy a compressor without that. But MCH6 is built the cheapest way.

 

[iain/hsm]

That is a fanciful claim, but what is it based on?
For comparison: pistons, cylinders, cylinder heads and valves experience approx. 2500 load changes per minute without failing immediately !!!

I'm really sorry to tell you this but Agro's claim is not only perfectly valid it's 100% accurate.

Agro clearly stated and I quote: " Load change is worst a filter housing can get."

This statement above by Agro is not only true but it's valid accurate and stands alone. Pressure to zero load cycles on a filter shell reduces the design cycle life expectancy.

Now CG43 your statement is also 100% true but by implication the problem is in grouping the two together I quote for reference
"For comparison: pistons, cylinders, cylinder heads and valves experience approx. 2500 load changes per minute without failing immediately !!!"

Now although your statement above is true It's only true in isolation.
IMHO you cannot compare the rod loading on a piston effecting the conrod crankcase and bearings with that of a filter tower by using the same application criteria given to that of the filter tower.

Now for the Engineering in detail you all love: Further
1. Loads on the pistons are not the same as those on the Piston liners or cylinders.
2. Loads on the cylinder heads are not the same as those on the valves. I could go into detail but for now.

To calculate the actual numbers the real loads on the pistons on a properly engineered compressor from an engineering consideration.

A 76mm (3") diameter piston the 1st stage on our properly engineered compressor at Top Dead Centre TDC from ambient inlet pressure will create only 321.36 Kg (707.26 Lbs) at TDC
By contrast at Bottom Dead Centre.......... Zero (0)

Conversely at the 2nd stage of say a 32mm (1.25") piston will create at TDC a near balance of 350.25 Kg (770.55 Lbs) at TDC a near enough balance for the sake of 70 lbs ( comparing 1st with 2nd) While at BDC a negligible 55.81 kg (122.79 Lbs) due to the residual back pressure from the 1st stage discharge side

And so on while the load on the thin filter shell wall is 3000+ Lbs
The kicker is the material difference and the cyclic load design.
While its perfectly possible to design a pressure vessel under a code of your choice for 100,000 reversal of pressure in a say a scuba cylinder you cannot bolt this onto the loads from a compressor.
Well not without some degree of confusion.

 

[iain/hsm]

Never have seen a compressor run for several hours; guess it is possible.

That's because your running a piece of recreational paint ballers junk formally known as the MCH-6. Have you considered the new I-CON vI I hear its painted in a very acceptable shade of black and very suited to the Italian uninformed mass.

 

[iain/hsm]

I guess I don’t know how Coltri and Rix compressors work,

Differently very differently. ............Now we know I guess lol

 

[Tanks A Lot]

That is a fanciful claim, but what is it based on?
For comparison: pistons, cylinders, cylinder heads and valves experience approx. 2500 load changes per minute without failing immediately !!!
[...]

I didn't want to reply further to the topic as it seems you have made up your mind on the function of the PMV, with which I strongly disagree, but the above statement is outright dangerous.

There have been a couple of accidents that lead manufacturers like Bauer to restrict the pressure cycles on their filter housings, as well as the oil- & water separators.

There are many different filters and separators in use, all of them with different characteristics. But making blanket statements along the lines of "load change isn't such a big deal for housings" is not the way to go. They absolutely can be under certain circumstances.

The max. number of load cycles for the P21 Central Filter Assembly is 4,500 if operated at the max. allowable pressure difference range of 330 bar (4,700 psi). For a pressure difference of 225 bar (3,200 psi) the max. no. of load cycles is 63,000.

This comes from a P21, which is typically found on a Bauer Junior, which is comparable to a Coltri MCH6. Coltri themselves doesn't reference this problem at all. This may be due to them using a superior alloy or simply ignoring the issue. I honestly do not know which one it is.

Also from Bauer:

(PMV) keeps the filter housing continuously under pressure to increase the partial pressure on the molecular sieve. So the speed of the flow through the cartridge is reduced, which increases the purification effect even more. Load cycles are reduced, too - a positive effect on the lifetime of the filter housings and the operating safety.

 

[Agro]

Coltri themselves doesn't reference this problem at all. This may be due to them using a superior alloy or simply ignoring the issue. I honestly do not know which one it is.

1) An average MCH6 never ever, never ever, never ever will reach a high number of load cycles, so problem does not exist.
2) I am sure Coltri does not care about this topic.

 

[Agro]

Have you considered the new I-CON vI I hear its painted in a very acceptable shade of black and very suited to the Italian uninformed mass.

The I-CON is a renamed MCH6. I have my theory about this. If you make a google search about MCH6 you will find very much very bad experiences about it. So they changed name, it seems to be an other compressor. Good marketing.

As far as I see on Coltri's website the I-CON still has no PMV as a standard. I think it's still an option only. Very bad but of course cheapest way.

 

[Wallowa]

That's because your running a piece of recreational paint ballers junk formally known as the MCH-6. Have you considered the new I-CON vI I hear its painted in a very acceptable shade of black and very suited to the Italian uninformed mass.

You really are a one-pony show.....do you ever get tired of hearing your own voice? Italian uninformed mass? Junk? Same old jaundiced bloviating drivel...filter and separator towers could fail? Paintballer junk? Spouting quasi engineering terminology to vouchsafe your prejudices while trying to establish your expertise does not work.

Since Agro and you are the flip side of the same coin....Coltri in USA is distributed by Nuvair and they sell the MCH-6 Icon with the 1,800psi PMV and no they don't leak.....Coltri MCH-6 iterations have been successfully used by a lot of divers over many years and they will disagree with all your angst against Coltri.

Both need to stop vilifying what has been a top selling and used compressor and try offering useful compressor information.