Filter/Water Issues

[IyaDiver]

Now I show you what happened to a user who does not know how to maintain his compressor.

01. PMV was set OPEN............yep OPEN or no back pressure at all.
02. Oil was over filled by approx 300cc ( 1 cocal cola small bottle ), so air production becomes OILY AIR production.

03. Filter used way way way beyond its limit. I think easy 3-4 times the table limit.


Air production smell like a dead rat........ yuccckkkk !!!!

However I seen worse case.
Its a long story but you wont believe what I had seen during my dive travel to some remote areas where there are dive compressors but users has no clue about filter life or maintenance.:shocked2:

 

[dchango]

Ray,
I agree, I am a little leery of adding marbles or other household items to it. I was just wondering if there was a kit made to improve the performance.

Thanks
Damon

 

[dchango]

Thanks KWS, you're right it is a good article.

read this, this should give a lot of insite and is a very well written article

Neptuno's World Articles - Understanding SCUBA Compressors and Filtration

 

[dchango]

Thanks IYA,

Wow, that’s a lot of info, appreciate the pictures also. I will recheck the level on the unit and see if there is any clogging of the orifice. I know that temperature plays a role on the duration of the filter, how did you calculate the useful life of the filter? The filter that I pulled out was that dark tan color, so it was used way too long. I guess I should be checking it more often, but how often should I check it, every couple of hours? I really do appreciate all the help, I’m trying to learn everything I can about these beasts.

Thanks
Damon

 

[rcontrera]

The disposable filter cartridge that is supplied for that machine is rated at 9000 cubic feet of air under optimum conditions ... about 15 hours for the MCH16.

I think I would start checking at about half that until I got a good feeling for a "normal" for your conditions. You may want to put a moisture eye on the outlet of the compressor for a little easier indication. With inlet and outlet fittings and an indicator card, it should cost you less than a hundred bucks but is a lot easier than dumping the pressure and pulling/inspecting cartridges every few days.

 

[dchango]

Okay, I will start checking every 6-7 hours. I do have a moisture/CO2 eye on my unit. I installed a new moisture strip and CO button back in July or August, and it was always blue (about the same blue as the machine) the whole time pumping. That was one reason I was surprised when I pulled the filter, and it looked the way it did. I‘m going to try to get that check valve installed this weekend, again thanks Ray for all your help.

Thanks
Damon

 

[IyaDiver]

Google this and you will get a XLS file. I dont know why I cant attached a short link.
scubaengineer filter life calculator

Bauer also has their own XLS version which you can adjust the molecular sieve quantity and use it for different compressor brands.

I played with Bauer P21, P41 and P81 filter system a great deal. But have abandoned P21 size, too small.
Using 39C as final temperature to compensate filter life, I never go wrong. I am at 30C almost all year round. I use extra forced cooling too.
In fact since I am not doing ice diving, I can extend a bit more life because air dryness only need to be at -48C dewpoint and not -55C.
-48C is only to make sure the activated carbon and hopcalite to works as it should.

Example , my Mariner 200 with P41 has used-up 12 of 675 grams MS filter cartridge ( with hopcalite P/N 67224 ) so far never off the mark and never any MS get tanned color with 39C as final temperature. I measure final water separator temperature skin temperature in real time with a thermocouple. Its between 36C to 40C depending on how long I run in one go. Its near 600 hours running already. I even measure the weight of my expired filter cartridge P41 down to 2 grams accuracy. Its not all water moisture adsorbed, some other "bad stuff" too, based on total weight between new and expired cartridge. Deduct the potential water weight & weight as new, the balance is whatever bad stuff an oil based compressor is producing.

By monitoring water condensate color and oil content, you can also tell your piston rings conditions or how much piston blow-by is leaking. More oil traces in water condensate is another sign of excessive piston blow-by. Oil can tan MS too you know.
By weighing my filter cartridge expired weight, I can confirm increase weight could be the extra oil being adsorb. I actually look for anomaly or out of pattern condition and this can be done, because since new I been taking all these notes for my compressor. Sooner or later piston rings will be worn out.

Here is the last few cartridges I measured :

08. P/N 67224, CO remover. 17 Feb 2011. Weight 1402 grams. 9 April 2011, 1630 gram. 49 hours.

09. P/N 67224, CO remover. 9 April 2011. Weight 1431. 27 May 2011, 1659 gram, 49 hours.

10. P/N 67224, CO remover. 27 May 2011. Weight 1418. 18 July 2011, 1652 gram, 49 hours.

11. P/N 67224 CO remover. 18 july 2011. Weight 1392. 10 Sept 2011, 1635 gram, 49 hours.

12. P/N 67224 CO remover. Sep 10 2011. Weight 1387. 31 Oct 2011, 1630 gram, 49 hours.

If you see the extra weight after expiry, it is between 228 grams to 243 grams. Of course there is a bit deviation on final temperature depending how long the compressor run in one go, hence more water in the air and ambient temperature may vary 29 to 33C but I use 39C as reference for final temperature. The cartridge I use is 675 grams of MS. In theory I probably load it up to 21-22% of water or approx 141 to 148 grams. So there is approx 100 grams of unknown being adsorbed.... and some of those are oil for sure.
If one day I start getting expired weight increase to say 260 grams consistently under the same working condition, something is wrong with my compressor. Bauer 41 filter cartridge is aluminum and not easy to cut open. So far I have cut number 4 as per photo I showed you and will start cutting open again when I see 250+ grams consistently as extra weight and surely watch out for the water condensate color and oil level.



If you want manual calculation, this is how to calculate filter life , based on PMV set at 150 BAR and tank fillling to 207 BAR.
Volume of air which can be processed: ( this is available in Bauer user manual ).

Va [m3] = 0,2 x mMS [g] / (X [g/m3] / p [bar]) = 0,2 x p [bar] x mMS [g] / X [g/m3]

Va[m3] is cubic meters of air
0.2 is the 20% water adsorbing capability of the molecular sieve. Yes, not 23% because there must be a buffer for dry air.
mMs[g] is mass of Molecular Sieve in grams
p[bar] is the filling pressure of the tank in BAR
X[g/m3] is the water content of air per cubic meter at final temperature
/ means divided by
x means multiply by


Like this based on a Bauer P21 filter with 68 grams MS :

0.2 x 200 BAR x 68 grams divided by 51.21 ( assumed 40C final temperature ) is = 53 M3 liters of air use .
53 M3 is 53,000 liters is equal to 4.4 hours of a 200 liters per minute compressor run at 200 BAR.

Water content in air based on temperature at 100% humidity ( yes in a compressed air situation it is a 100% humidty ).
See photo attachment

Happy air making.....

 

[dchango]

IYA, Ray,

Thanks for all the information and help. Yesterday, I started the installation of the new check valve as suggested by Ray. I also checked in the bottom of the filter tower for that orifice that maybe plugged, there isn’t one. The only hole is the drain line connection that runs to the auto drain solenoid valves.

I decided to check the whole auto drain system to make sure it was flowing and not plugged. I took the line off the bottom of the filter tower, removed the plunger from the high pressure solenoid and tried to blow through the line. The air flowed, but not through the solenoid valve it was going into the water separator.

So, I took the whole auto drain a part system. The fitting that was in the drain block was very rusty and the fitting in the solenoid valve was packed with rust pieces. I tried to blow through it and very little if any came out through the valve. I removed the fitting from the valve side and had to run a punch through it, when I did a little sintered filter came out (the same type that is in the 1st stage of Scubapro regulators). The filter was extremely rusty and plugged (photo).

I’m sure that this is one of the issues of my system has also. With the auto drain only purging for 5 sec each time, it is not purging much of the water and over time it is building up in the filter tower.:shocked2:

I looked in the scheduled maintenance in the Coltri manual it doesn’t have it listed in the scheduled maintenance table, but if you do a PDF word search for “SINTERED” it is mentioned on page 53 and states that it needs to be replaced every 250 hours (it should be in maintenance table). The person that I bought it from said that all the service was completed up to the 500 hour service. Obviously this was NEVER replaced and had probably been an issue for quite some time, even before I purchased it.

Like I said, I’m still learning about having your own compressor. I do appreciate all the help, without it I would have never worked on the auto drains and found the bad filter.

Thanks
Damon

 

[IyaDiver]

Hi Damon,

Good you solved the 1/4" water level issue. I never rip open and auto drain system, so I don't know how its internal are and If I do open one it will be Bauer one and much different than what you have. I would not want to install auto-drain on my compresor even if its for free. The reason is simple, I don't trust them. Two failure points, electrical command by the timer and the actuator failing to open, either the electric coil are burned or mechanically it is stuck. In a pneumatic-electrical combo system like what the Bauer uses, there are air-ways in the pneumatic needing to be cleaned, another point of failure. Water Separator no 1 air output as pneumatic power source is not the cleanest air source.

If I ever ever install auto-drain, I will choose those using 5000psi all electric actuator, stand alone and no pneumatic pick-up whatsoever to complicate repair or maintenance and 1 less extra point of failure or leaks from the pneumatic. I wil also use two separate water condensate collector bottle.

If the water separator no 1 drain failed to open, my 3rd stage piston will be damaged. Since there are at least two drains on a 3 stage compressor, hard to tell by a discharge sound, which one failed to open. This is my biggest worry. Filter melt down from a failed auto-drain on water separator no 2 flooding a brand new super dry molecular sieve is another worry, rare but it does happen and have happened to a friend neglected compressor, plain lazy staff he had. Total loss his P21. I can't imagine the heat potential of the 13X, 68 grams only of MS 13X on a P21 and it can burn the plastic cartridge, oil traces.... and hence extra fuel to burn the whole P21 assy........my my. If My 685 grams P41 filter tower get the same problem, I think my whole compressor will be on fire.

At heat energy of approx 1,800 btu per pound of water adsorbed for 13X do sound scarry. I checked a BTU is equal to raising 1 farenheit for 1 pound of water at 1 ATM. Luxfer request us to condemn a cylinder that has been exposed to 350F temperature. The filter housing alu alloy if there is such a pre-caution ( it should ) would probably be identical. Even with no filter melt down, I could risk weakening my filter housing if the auto-drain failed but detected in time.

I also make it a habit to inspect the color of the water condensate. I never fully open up the condensate bleed valve. I also want to catch the water condensate on a small clear plastic cup once in a while. By not opening up the valve a 100% , I also limit the reduction of pressure cycle life of the water separator. I know water separator no 1 technically has no pressure cycle life limit due to 50BAR operation but a 2nd water separator combo unit like a Bauer P21 ( P Zero ) is 35,000 cycles 0-230-0 BAR and only 4,000 cyles if 0-330-0 BAR. Not that I will use the compressor that long ( I am a 207 BAR player ), but....you know, less fatique the better it shall be. As far as I know, only Bauer and LF provide pressure life cycle for their presure vessel, but Bauer is more comprehensive in the data, well Germans are like that, very detailed.

Have fun with your compressor and dive safe yah.
.
IYA

 

[iain/hsm]

but Bauer is more comprehensive in the data, well Germans are like that, very detailed. IYA

Hi Iya.

IMHO Bauer is NOT more comprehensive with the data, they just didn't disclose the fact that there TUV approved separators were not up to the job in hand.
That and because of the number of explosions they had with there original TUV approved separators they changed the material improved the tensile strength.
Originally their separators (M76 thread on a 95mm OD and 270 length) were rated by TUV for 350 barg but also only designed under TUV for ridiculously
minimal 2.5 to 1 safety margin.

It frankly was an accident waiting to happen IMHO the german TUV lot acted clueless as to the material, wall thickness tensile strength and internal thread
architectures, but in typical germanic approach expected everyone else to comply.

In the UK we didn't, and years later as they started to explode under load. (The material was HE30TF or 6082 the Germans designate this as ALMG SI1 F31
it will be stamped on the shell, but another critical flaw was that the working pressure to burst was only 2.5 to 1) Therefore only a 12,000 pig burst design

The redesign issued is now with a 4:1 safety boundary, so now a 20,000 psig burst design.

Most filters and separators now are designed under the ASME 4:1 safety code if the external and or internal dimensions need to be the same as the older
weaker material then the tensile strength of the alloy needs increasing. The old HE30 TF or 6082 or ALMH SI1 F31 has a tensile strength of around 270 Mpa

By comparison most new designed filters are in 7075 T6 alloy with a tensile of over 500 Mpa, also to factor in thinner wall thickness but with greater
strength in a non corroding atmosphere. Zuführung durch die Technik des Esels eines Esels,
Or as we say over here "the backside of a donkey is an ass". LOL Iain Middlebrook