Filter/Water Issues

[dchango]

A couple of questions. I have a Coltri MCH-16 Compact and my first filter that I had installed I got a little over 12 hrs on. I know that temperature plays a big role in the longevity of the filter. Our summer temps in the early mornings in my garage are high 90’s low 100’s, leaving the doors open drop it somewhat outside air usually 10+ degrees cooler. So I try to fill then. Being this was my first filter (the filter is a LF disposable), I’m not sure what they should look like when they are spent(never seeing one). The one that I pulled out was completely saturated the MS went form a light tan to a dark tan and the bottom of the tower had water sitting in it, about a ¼ inch. The weird thing is, I always purge the system to zero when I am done pumping. So, where did the water come from? Did it come from the filter or am in not purging enough? I finally got my purge timers fixed and set to 7 min off and 5 sec purge (thanks to Dan at Nuvair), but I recently reset them to 5 min off and 7 sec purge (don’t know if this will help, but it can’t hurt). I have the PMV set to about 1900 psi.

I decided to do some exploration on the water separator and see if there is an issue with the separator. I took it apart from top to bottom and found nothing, literally nothing. Shouldn’t there be something in separator like pieces parts to collect the water? The only thing was in the bottom it looked like a tube with several holes drilled into the top of it. The top half had nothing in it, just an empty tube. I looked on LF’s site and they have a Coalescor Hop-up Kit, but after some research the kit installs into the filter tower, so I would need to find a new or somewhat used Coltri filter tower. Where could I locate one of these for a reasonable price, and do I really need to go this way? Any info would be appreciated.

Thanks
Damon Chango

 

[CraigAClark]

First stop purging the filtration when finished pumping! Second, How fast are you depressurizing the filtration when you go to change filters? In your ambient temps only expect to get 70-75% life expectency from the cartridges. Increase the PMV setting to 2500 psi. Sorry I don't have time for long explanations.

Craig

 

[dchango]

Thanks Craig for responding,

First stop purging the filtration when finished pumping! Okay, I can stop purging, but would still like to know why. Second, How fast are you depressurizing the filtration when you go to change filters? Just purged by the "test purge button". When the gauges read 0psi I opened the purge valves in the back of the unit, let the unit sit for several hours, then changed the filter. In your ambient temps only expect to get 70-75% life expectancy from the cartridges. I do understand that higher temp mean shorter life, but would adding a Coalescor Hop Up Kit give me a little advantage over moisture, and am I missing any internal parts in the water separator? Increase the PMV setting to 2500 psi.The PMV can be set higher, but Dan from Nuvair said to set it here. Don’t get me wrong I am not questioning your setting or information just asking why? Sorry I don't have time for long explanations. Maybe when you have some extra time you can explain in a little more depth. I am still trying to learn as much as I can about these things, and do appreciate any and all help.

Thanks
Damon Chango

 

[rcontrera]

If you have the auto drain hooked up to the filter tower as well as the two separators, you may have water being blown into the filter tower during the blow down. The standard block on the back of the machine has two HP taps and they are connected internally. I always hook up a check valve on the tower blow down line so that water cannot be blown back into the cartridge.

It sounds like you have the old moisture separator. The bottom separator looks like a tube sticking up from the bottom with a couple of holes in it ... pretty basic. And the top part is even more basic ... just a chamber. They work OK but the one they came out with in 2006 is a lot better. ber

Now ... all that said, I think putting the check valve on the final tower blow down line will fix your problem ... along with adjusting the PMV to 2500. The higher the pressure, the denser the air and the better the moisture separation.

 

[dchango]

Thanks Ray,

I always hook up a check valve on the tower blow down line so that water cannot be blown back into the cartridge. Where should the check valve be located, on the bottom of the filter tower or right before purge valve? It sounds like you have the old moisture separator. Well what options do I have, are there any upgrades to make it function any better? …along with adjusting the PMV to 2500. I will increase the PMV. Thanks for the information.

Thanks
Damon Chango

 

[rcontrera]

Placement of the check valve depends on what type of drain line you have off the bottom of the filter tower. If you have a simple hose, then it is an easy fix to get one of the cheap check valves and install JIC inlet and outlet fittings on it and just disconnect the hose and put the check valve in line on either end ... whatever is easiest. If you have a hard drain line, then a little cutting of tubing is in your future and it is just easier to work up on the block rather than down on the bottom of the tower.

Yes, you can purchase the new drain system. But that is expensive and may take a little tubing bending/reconfiguration to install.

 

[dchango]

Ray,
Is there any mod or upgrade the I can do on the water separator to make it more effective? I did order a check valve and will install it when it arrives. Thanks for your help.


Thanks
Damon Chango

 

[rcontrera]

Of course, you could purchase a whole new moisture separator. But I think that would be way too much to spend just to get a little more water out. I HAVE seen guys fill the top portion with marbles or stainless steel pot scrubbers to give the air more surface area to loosen the moisture. I am a little leery of putting anything inside that could block the outlet but the theory is sound.

 

[NAM001]

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

Thanks Craig for responding,

First stop purging the filtration when finished pumping! Okay, I can stop purging, but would still like to know why. Second, How fast are you depressurizing the filtration when you go to change filters? Just purged by the "test purge button". When the gauges read 0psi I opened the purge valves in the back of the unit, let the unit sit for several hours, then changed the filter. In your ambient temps only expect to get 70-75% life expectancy from the cartridges. I do understand that higher temp mean shorter life, but would adding a Coalescor Hop Up Kit give me a little advantage over moisture, and am I missing any internal parts in the water separator? Increase the PMV setting to 2500 psi.The PMV can be set higher, but Dan from Nuvair said to set it here. Don’t get me wrong I am not questioning your setting or information just asking why? Sorry I don't have time for long explanations. Maybe when you have some extra time you can explain in a little more depth. I am still trying to learn as much as I can about these things, and do appreciate any and all help.

Thanks
Damon Chango

 

[IyaDiver]

I decided to do some exploration on the water separator and see if there is an issue with the separator. I took it apart from top to bottom and found nothing, literally nothing. Shouldn’t there be something in separator like pieces parts to collect the water? The only thing was in the bottom it looked like a tube with several holes drilled into the top of it. The top half had nothing in it, just an empty tube.Damon Chango

The Bauer PZero ( P21 as called by European or Asian user ) uses that same pipe you mentioned. P Zero is a filter housing and water separator combo. They are playing with gas-law Damon.
The small pipe is like an orifice in a dive regulator 1st stage. The air gets cooler exiting the tube because pressure reduced ( air expand into filter housing ). That act of cooling the air.... juice out water vapor out of the air, aka dewpoint reached. Also since the pipe jets air out, at the same time oil traces within the air will hit the filter housing internal wall.......... kind of sticking there. I never opened up a Coltri water separator or its filter housing but more or less all these compressor manufacturers will have the same engineering set up.

Purging a filter tower which if it is also a water separator combo, there is no way you can purge a 100% its water content. Those water droplets sticking on the wall will stay as droplets. Later when compressor shut down and no more swirling of air inside, it will settle to the bottom of the housing and that is that 1/4" of water you saw. 1/4" is too much actually, should be half that as the bleed hole/valve will discharge the water. The only way you will see 1/4" of water on the filter housing bottom is if the compressor is not on flat ground and the water wont travel to the bleed hole. Other possibility is a mild clogging on the bleed hole.

See attachments. That is a P ZERO ( P21 )
The dark shadow on the larger wall diameter you see are water droplets.
The green circle I marked ( smaller diameter ) is the filter housing section, so outside that green circle is the water separator section, hence I call this a combo of water separator and filter housing.

If the entire Molecular Sieve bed is tanned ( water soaked ), you have used it beyond its limit.
See attachment of a Bauer P41 filter cartridge photo, which is already expired but temperature calculated/compensated to still be within -48C or -55C dry, that is how it should look like. Dry , but cant adsorb water vapor effectively anymore. Tanned is the same as flooded with water.


Now, see the two big filters set from Mako, attached. That is a 27" type. If that is a Bauer, that is a P2/P5 filter housing/tower size for USA market and P61/P81 for European market, same thing just different name.

The 100% molecular sieve cartridge is placed in Tower 1.
The tripple media ( PD-1803 ) cartridge is placed in Tower 2.
The two filter towers are connected in series. The two filter cartridges are changed based on special dewpoint sensor reading.
The remaining dryness value of this filter is at -48 Celcius or -55 Farenheit. It still can collect water vapor no problem but the activated carbon dan the Hopcalite bed will not be effective above -48C dryness.

Notice the used ( left one ) tripple media filter cartridge ( tower 2 ) has fogging on the activated carbon region.
That is the hopcalite and activated carbon media actually working.

In a compressor with twin tower this huge and being a series connection, it is normal to see the cartridge in the 1st tower , its molecular sieve tanned a little wheeny bit at the point of air entry......as per photo. By the time the air exit the top part of 1st cartridge and then to 2nd cartridge, the final output will be very dry.

In a small filter size and single tower like ur MCH16 or Bauer P Zero ( MS = 68 grams, no hopcalite ) , P31 ( MS = 312 grams, no hopcalite ) and P41 ( MS = 685 grams with hopcalite as per photo ), tanning of the molecular sieve means you over used your filter cartridge. A MCH16 filter size at say 95 farenheit SHOULD NOT be used to 12 hours. That is like only 168 grams of molecular sieve in there. Ray should be able to tell you exactly how much is the molecular sieve content of newer MCH16, if there is any difference. My data shows 168 grams and at 95F, you only have 8 hours maximum. To be exact 7.4 hours is what I get.

Have fun and dive safe.

IYA