Coltri MCH 6 humidity issue

[ti325v]

Right on Ray. I hope he listens. Shipping to me is in another universe, you have sent me stuff that arrived six months later, as it had to be hand carried into the country by the friend you shipped it too, this man is on mainland Europe.

 

[pisoiu]

I wrote a long reply, then the server went down for maintenance.
I need to caution you strongly, which I did in my reply to Peter (Lost) ....Funny as he and I both learned with the same crappy Chinese compressor.

Sorry to hear that, it happened to me also..

you obviously did not read or understand the article I linked too.

I read it and what I did not uderstood, I asked. This is why I asked, to clarify what is not clear.

This is diving my friend, man up and spend the money....Shipping was over $250 for me to sort out my filtration. (Add another $1600 for the parts) if you cannot find a pmv in Europe..(simply ridiculous, you are lazy) and you do not know what you are doing, do not do it.

That's funny, being accused of laziness after coutless hours of researching about how to service a compressor. I never said I cannot find one in Europe, I asked for some directions because I don't know what to look for and where to start looking for. If that's laziness....
Ray kindly showed me what he has but I think it's not ok, I will tell later why. I don't mind spending money on what I need but excuse me if I look for a way to pay as less as possible for non essential stuff such as shipping fees, vat to goods imported from outide EU, etc.

...we are trying to help you to fix your problem by telling you that you must have a functional PMV.

And for that I am trully gratefull, your help is very valuable. But please just don't slap me that hard, I just want to understand things, even if I seem to post stupid (at least from your point of view) questions.

25 to 50 dives and diving solo ?

This is not the place for this discussion.

You said it yourself, you do not understand the physics and you are choosing not to understand a whole lot more then that. If you do not understand then listen to those of us who do, get the PMV.

I do not fully understand the things related to humidity, the theory of gases is another story. That one I understand.
Now back to PMV. Ray, that valve I really do not see where would fit. That's because my compressor is an older model. I attached 2 pictures with it. The hose outputs directly from the filter tower and if I understood correctly, there the PMV must be installed, to keep the pressure up in the whole filtration system. That valve you showed me will not fit in my opinion. Shipping fees you told me are reasonable, those fees I know about (from ebay) were no lower than $40-50 in the last 2 years.



LE: Found a PMV here: Pressure Maintaining Valves « Midland Diving Equipment Ltd
I just need to see how to connect it.

 

[Peter69_56]

I bought mine from ebay for about $100 AUD and $7 shipping from Compressor Stuff. Out of curiosity, what's the pressure set point for this valve if someone knows?

Idealy the priority valve should be at the discharge of the filter stack, however I suspect at a pinch you could put it before the tank inlet at the end of the whip, but its effectiveness would be reduced on startup as you are trying to reduce throughput at low pressures which increases velocities through the filter stack. Any additional storage area (read hose and fittings) adds to the time before the filter is at operating pressure, thus the potential to contaminate the filter more quickly due to lower dwell times in the filter stack. The longer it takes to get the air though the stack the better the air is filtered and the longer the filter lasts. Hence why weighing the filter when new and then checking on a regular basis on weight to determine end of life.

The Bauer end of life computer you can buy is based on filter stack, known filter element, known back pressure and known fill time of the stack along with known air flows, stack temperature etc. Thus using the "emergency" valve at tank method, while better than no priority valve at all, is fraught with danger in assuming you can get a specified time from the cartridge from the specs. As you have clearly found, with no PMV your filter is stuffed quickly, with no PMV but using the discharge valve, I would bet filter life is still not near optimal and should be checked after a few fill periods to see how you are going. Once you install a PMV it should then perform somewhere more near specs (but still needs checking to confirm), dependant on ambient temperature, number of tanks filled per period and total air volume per period. etc etc.

Basically with temperature, the hotter the day, the more water can be evaporated and held in a volume of air. In the Antarctic, air is very dry as it will not stay as a vapour but drops out as ice/snow/rain. Thus with high temperatures, the air can contain more water thus filter lasts less time. Also things like filter stack temperature play a part as well.

As a sample from my filter calculator (Thanks to Steve Burton ASSET Thailand)
100l/m flow
140 BAR PMV set point
Ambient temp 20C
Filter tower temp rise 15C
3.08 hrs run time MS
50 hrs run time AC
9 cylinders filled
18506 litres flow

Now change
Filter tower temp rise 25C gives;
1.8 hrs run time MS
50 hrs run time AC
5 cylinders filled
10857 litres flow

Change only ambient temp
100l/m flow
140 BAR PMV set point
Ambient temp 10C
Filter tower temp rise 15C
5.48 hrs run time MS
50 hrs run time AC
16 cylinders filled
32861 litres flow

Change back pressure;
100l/m flow
20 BAR PMV set point
Ambient temp 20C
Filter tower temp rise 15C
0.58 hrs run time MS
50 hrs run time AC
1.72 cylinders filled
3504 litres flow

It gives you an idea of how things affect filter element life (in theory).


rcontrera on eBay

---------- Post added April 30th, 2015 at 10:44 PM ----------

The priority valve we install on all our MCH6 compressors is a very simple little guy. We pull the fitting out of the filter housing and replace it with another that screws into the valve. Then we put an adapter on the outlet of the valve to hook to the hose.
View attachment 207628

Whats the actual factory setting for backpressure on the valve. This is the one I fitted to my secondary filter. Thus each filer has one so no filter can have flow at low back pressure.

---------- Post added April 30th, 2015 at 10:48 PM ----------

Rcontrera

The ColtriSub Portable Scuba/Paintball Compressor Filter you offer on ebay? What is the filter element in it, is it the MCH6 filter element?

 

[ti325v]

Peter that is the regular aqua-enviroment PMV, with a fixed set point..I do not recall ever seeing one that was not adjustable with the exception of that one.
I will not enter into the debate about the quality of that particular valve has it has been debated endlessly, Ray sells it, Ray sells the compressors.
It is inexpensive, it works..any thing will work a heap better then nothing.
Also, I linked all of that info to this gentleman, if he had so chosen he could have learned all of that himself and if he had P.M.ed me I would have sent him all of Steve Burtons stuff, even discussed where Steve may be off the rails a little bit...Not that the guy is not sharp, he is. Also I would have been happy to send on copies of a huge library of reference material I have acquired. He chose not to take that road, which would have required a bit of work. Maybe given him some real insight into what he is doing, not just wasting his filters..the whole process. He chose not to take me up on the offer, I think passing info like this on to people who are not prepared to learn, well we do not know what they are gonna do with it, and the simple fact that that a national manufacturers rep told him to do something, yet he knows better...I do not think it wise to enable somebody in a situation like this.
If you cannot tell when your PMV is releasing, it looks like you asked this question....you may have a defective pmv....a very simple check.... start compressor, open your fill whip, observe the pressure when the whip starts to release gas...problematic if your final pressure gauge is on a single whip, but that is easy enough to work around.
Set point is 1900 psi.
Item # 1310, 1310 Back Pressure Regulator On Aqua Environment Co., Inc.

 

[rcontrera]

I see why you are having a problem figuring this out! Pictures are wonderful help in that they show this as a customized assembly. The top caps for the separator and the filter housing are interchangeable and yours have been swapped. The gauge has been removed and that block installed. The standard hose connection has also been removed and a plug put in it's place.

It is still not a problem to install a priority valve, though. The hose hooks to the yoke by a JIC fitting so you just need to pop the hose off, use JIC to pipe adapters to install the PMV in between the hose and the yoke. I assume you have a shut off valve, gauge and bleeder on the other end of the hose. If you don't, you need that too.

 

[pisoiu]

I attached a picture with the hose. It is an older picture, sorry for bad quality.
There is no shut off valve.

 

[rcontrera]

As it sits right now, when you open the bleed off valve after filling, you are draining the pressure all the way down on the filter, separator, compressor and all the associated piping/hose. I assume that is correct?

When we install a priority valve, it work a little like a metering valve and just seep a little air after you drain the hose. Over time and dirt buildup, that seep may increase to a point to where you can't get the filler off your tank. Plus, it may also let all the air out of the system as it sits. You should also put a valve at the filler attachment so that when you bleed off to remove it from the tank, you leave the rest of the system charged.

 

[Peter69_56]

Peter that is the regular aqua-enviroment PMV, with a fixed set point..I do not recall ever seeing one that was not adjustable with the exception of that one.
I will not enter into the debate about the quality of that particular valve has it has been debated endlessly, Ray sells it, Ray sells the compressors.
It is inexpensive, it works..any thing will work a heap better then nothing.
Also, I linked all of that info to this gentleman, if he had so chosen he could have learned all of that himself and if he had P.M.ed me I would have sent him all of Steve Burtons stuff, even discussed where Steve may be off the rails a little bit...Not that the guy is not sharp, he is. Also I would have been happy to send on copies of a huge library of reference material I have acquired. He chose not to take that road, which would have required a bit of work. Maybe given him some real insight into what he is doing, not just wasting his filters..the whole process. He chose not to take me up on the offer, I think passing info like this on to people who are not prepared to learn, well we do not know what they are gonna do with it, and the simple fact that that a national manufacturers rep told him to do something, yet he knows better...I do not think it wise to enable somebody in a situation like this.
If you cannot tell when your PMV is releasing, it looks like you asked this question....you may have a defective pmv....a very simple check.... start compressor, open your fill whip, observe the pressure when the whip starts to release gas...problematic if your final pressure gauge is on a single whip, but that is easy enough to work around.
Set point is 1900 psi.
Item # 1310, 1310 Back Pressure Regulator On Aqua Environment Co., Inc.

Thanks for the set point. I asked to confirm what I thought. I had already experimented and figured about 140 Bar (2050 PSI) by doing exactly what you stated, so I was close.

I bought that PMV as it was the only one I could find on the internet at the time. I knew I needed one for my secondary filter but struggled to find something I could fit up. Any recommendations as to what I should fit should it fail I would appreciate.

One of the big issues I have is to adapt American threads to British. Its such a pain. American is usually NPT and British is BSP or BSPP. Buying adapters in Australia costs an arm and a leg (I am not talking about buying unrated Chinese crap). I think I paid something like $45 for 2 small (rated) SS fittings from swagelock. I don't want my system blowing apart unexpectedly by using cheap brass unrated fittings, however sometimes its near impossible to get what one wants.

Do you have any info regarding the standard contents by weight (MS & AC) of the Coultri standard filter MCH6 I would appreciate the info as that's the way I determine end of life for the filter.

Also the Coultri filter stack sold with the MCH6 compressor, I assume it uses a MCH6 replaceable cartridge and is not a refillable type? (The ColtriSub Portable Scuba/Paintball Compressor Filter on ebay? What is the filter element in it, is it the MCH6 filter element?)

Any info you have on compressor operation I would appreciate. I did my Dive Tech course with Steve Burton and he is much sharper than I am with compressors and scuba detail and certainly increased my understanding. I wish I had gone to the course before I ventured into buying one as it would have saved me a lot of aggravation and money. I started off knowing zip about compressors and got badly burnt along the way. SO I am willing to expand my understanding of the how and why of it. I do now have some knowledge but its still not close to those who work in the industry, so any info, links, documentation is appreciated.

 

[rcontrera]

Correct ... the MCH6 filter cartridge is not refillable. In the US, we have three different types of replaceable cartridges ... one that is all 13X that we sell to paintball or industrial HP customers, one that is mostly 13X and also has a layer activated carbon for breathing air and one that also has a layer of a CO catalyst for those that may have CO. The personal filter uses the MCH6 cartridges.

 

[Peter69_56]

Correct ... the MCH6 filter cartridge is not refillable. In the US, we have three different types of replaceable cartridges ... one that is all 13X that we sell to paintball or industrial HP customers, one that is mostly 13X and also has a layer activated carbon for breathing air and one that also has a layer of a CO catalyst for those that may have CO. The personal filter uses the MCH6 cartridges.

Ok good thanks for that. The reason I asked was that the Chinese ripoff of the Coultri had a filter tower that looked exactly like the one you sell. The difference being that they did not have the intelligence to build it the same as yours internally. Instead of using a replaceable cartridge, they put in a small tube fixed to the cap. It was tiny and a joke. The O ring was so badly designed, that it was destroyed when screwing the cap on. From the outside it looked exactly like the one you sell. The screen washer designed to hold the filter material and felt washer rusted so probably made from steel, the retaining sirclip made of steel and rusted. Such a crap effort from them. From the outside though it looked like a Coultri.

Its a pity these crap compressors are out there, but there we are, "Let the Buyer Beware"

---------- Post added May 1st, 2015 at 09:34 PM ----------

Out of interest my compressor filter specs vs actual running

P21 Cartridge calculated specs for the conditions of use

23 tanks
7.79 hrs max run time
46740 litres throughput

P21 filter
New filter weight 191 gm, fully used 206.1 gm

MCH6 cartridge specifications
New filter weight 105 gm , fully used 111.5

Actual usage to date;
P21 actual weight to date 204.8 gm

MCH6 actual weight to date 105.5 gm

23 tanks filled (partial fills and varying sizes)
6.9 hrs actual compressor runtime
26,368 litres supplied.