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Molecular seive, Active Carbon, Coalescing filters Eh?? What do they all do?

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  • Molecular seive, Active Carbon, Coalescing filters Eh?? What do they all do?

    I've a Coltri and my supplier seems to think all I need for a filter is the inbuilt intake filter now fitted to my Coltri and some Molecular seive and all should be dandy. My gas is Brit utility company supplied , how I envy you Yanks with you own wells! Anyway, I'm confused, what is:

    1. A Coalescing filter ( I think) it removes oil - why is a bit of oil bad in a tank or an engine anyway? Oil hurts no one here?
    2. Why do i need Active Carbon? Why is it so vital if I already have...
    3. Molecular seive?

    I know the scuba boys have the lot, fair enough, we don't breathe our gas. The more the merreir I should have thought, but it all costs. Molecular seive I believe gets rid of wet stuff. Is Molecular seive the alll singing miracle worker, and if so will I walk on water?
    Last edited by BritCNGUser; 03-28-2013, 05:54 AM.

  • #2
    Re: Molecular seive, Active Carbon, Coalescing filters Eh?? What do they all do?

    @BritCNGUser
    1) Coalescing Filter - Collects physical liquids and mist/vapours. This can include Pump Oils, Natural Gas Liquids (drip gas), and water vapours near saturation.
    2) Active Carbon - would be needed if your source is SOUR GAS - typically Acidic due to presence of Sulphur compounds (H2S) or excessive CO2 (carbonic acids) - Activated Carbon binds these and makes the gas more pH neutral.
    3) Molecular Sieve - A superior gatherer of specific sized molecules depending on the type and size. ZeoLite (which is an alumino-silicate) with engineered pore sizes depending on the other mineralizing element chosen. Commercial sizes include 3A, 4A, 5A and 13X. The A stands for Angstroms, the atomic unit of measure of the pore size. 13X is @ 10A. 4A is the typical size for attracting water molecules. The unique property of molecular sieve media is that they attract a specific molucule size and reject all larger molecules, so you can 'tune' what you want to remove. My own utility supplied gas here in the US is not well processed and our local utility uses underground storage wells for surplus and surge capacity. It can be VERY WET.

    The real issue is avoiding the formation of Methane Hydrate under Pressure/Temperature conditions that are in our operating range. These Hydrates form in nature under the silt layers of the sea bed and contain vast amounts of the worlds known NG. Methane Hydrate in water is a greyish sludge which can plug up the pin-hole sized aperatures in the mechanisms of your main tank valves (like 'snot') and at colder temperatures the Methane Hydrates bundle themselves with ice crystals. These can become semi-permanent and un-yielding in winter meaning if you get the ice versions in your tank valve in winter, you may not be driving again until June/July.

    http://www.epa.gov/oar/caaac/mstrs/dec2012/sakai.pdf

    This report gives an excellent overview of the problems with un-processed NG. I could go on for much longer, but I think this outlines the answers to your questions. If you have additional questions, feel free to ask in PM or your next post.
    Attached Files
    '11 Fusion Bi Fuel & FMQ2-36 VRA
    (Former owner '09 Civic GX)

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    • #3
      Re: Molecular seive, Active Carbon, Coalescing filters Eh?? What do they all do?

      You might want to avoid the carbon filter if you are on a commercial gas system. It takes a lot of the ordorant (rotten egg smell) added to the methane to detect a gas leak.

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      • #4
        Re: Molecular seive, Active Carbon, Coalescing filters Eh?? What do they all do?

        Thanks for you answers. I'm not sure if i have Sour gas or how to find out, and Carbon if I understand htsi correctly (becasue we're removing odourant) is a no-no, so I'll forget carbon.
        I've a spare coalescing filter knocking about, so I'll stick it inline, can you say it best to put it before the MS or after it, or does it not really matter?
        Anotehr Q: What does the cartridge type filter (only about £3-4 pounds (say USDollar$7-8 each) do? By this I mean the filter after teh regulator at low pressure before entering the injectors.

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        • #5
          Re: Molecular seive, Active Carbon, Coalescing filters Eh?? What do they all do?

          put the coalescing filter first to catch the big drops.

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          • #6
            Re: Molecular seive, Active Carbon, Coalescing filters Eh?? What do they all do?

            Originally posted by BritCNGUser View Post
            Thanks for you answers. I'm not sure if i have Sour gas or how to find out, and Carbon if I understand htsi correctly (becasue we're removing odourant) is a no-no, so I'll forget carbon.
            I've a spare coalescing filter knocking about, so I'll stick it inline, can you say it best to put it before the MS or after it, or does it not really matter?
            Anotehr Q: What does the cartridge type filter (only about £3-4 pounds (say USDollar$7-8 each) do? By this I mean the filter after teh regulator at low pressure before entering the injectors.
            Cartridge type filters are typically only for particulate matter, and they are rated down to a specific micron size. If you are going to use a Molecular Sieve and have concerns for 'dust' migration downstream of it, that is where you would place the cartridge in my opinion. I don't use one personally. I agree with Cowboy on using the caolescing filter ahead of the MS to catch physical moistures.
            '11 Fusion Bi Fuel & FMQ2-36 VRA
            (Former owner '09 Civic GX)

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            • #7
              Re: Molecular seive, Active Carbon, Coalescing filters Eh?? What do they all do?

              I've not been in this parish for a bit, but I found out a little tidbit you might see as useful. I came to change the MS in my Coltri to find that actaully Coltri's filter cartridge contains both AC & MS within the same cartridge. Specifically designed with CNG in mind, it did not remove the 'smell' which does surprise me
              Last edited by BritCNGUser; 08-19-2013, 01:12 PM.

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              • #8
                Re: Molecular seive, Active Carbon, Coalescing filters Eh?? What do they all do?

                Coltri makes a filter that is just the molecular seive without the carbon that should fit your compressor. I use this in my MCH-5 and I know it fits other compressors. Coltri P/N SC000440-M. (at least in the U.S.)

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                • #9
                  Re: Molecular seive, Active Carbon, Coalescing filters Eh?? What do they all do?

                  A bit more info. yes you're correct Coltri make two filters, both use the same cartridge tooling and fit in the same body. Only as mine came there was disc sepeartor keeping the MS & AC apart, and was the CNG version. (Marked CNG) When I repacked I put both in as I found it.

                  I would post pics but the uploader won't play.

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                  • #10
                    Re: Molecular seive, Active Carbon, Coalescing filters Eh?? What do they all do?

                    To revive thsi thread. Having experienced problems with one stage it started to throw out more oil. This without the coalescing filter oil will coat the MS and AC negating these.. I heartily recommend a Coalescing filter in the first partof the cahin, if not for now, but for the day you have pump problems, and these will come as your compressor gets older. More applicable to oil type pumps, but any liquid getting to MS & AC is not good. Caatch the oil and water before it can get that far.
                    Last edited by BritCNGUser; 06-02-2014, 06:40 AM.

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                    • #11
                      Re: Molecular seive, Active Carbon, Coalescing filters Eh?? What do they all do?

                      Thanks to Dave I just picked up a 25 lb bag of this stuff for 80$ +20$ for shipping.
                      http://www.ppe.com/15cat/0118.pdf
                      Screenshot_2015-08-04-18-14-06.jpg
                      Attached Files
                      Last edited by trdscfjc; 08-04-2015, 08:23 PM.

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                      • #12
                        Re: Molecular seive, Active Carbon, Coalescing filters Eh?? What do they all do?

                        Got some issues with uploading
                        Attached Files
                        Last edited by trdscfjc; 08-04-2015, 08:58 PM.

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