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912ULS gas filter at 40 microns

in 912 / 914 Technical Questions 11 years ago
Is it OK to use a 40um gas filter on my 912ULS? Rotax says 100um. The filter element is stainless steel.
Comments?

Dave

  • Re: 912ULS gas filter at 40 microns

    by » 11 years ago

    That means the 40 micron filter will catch even finer particals than a 100 micron filter.
    It theory that means it's even better.
    But it also COULD mean it it's overkill (that there's no harm at all in having 99 micron particles getting through to the carbs) and that it will get clogged up sooner and need replacing (or if it's a cleanable filter, cleaning sooner). Since it's stainless steel I trust that it's a filter you just periodically clean rather than replacing it.

    Advantage of a stainless steel filter is it can't get damaged or have its ability to let fuel through by a bit of water or some unexpected chemical managing to make its way to the filter and getting absorbed by the filter material surface, as can happen with some types of filter material

    IMO no harm at all in trying it.
    If it starts getting prematurely clogged up that's likely to happen slowly not suddenly, I imagine, and you'd get whatever symptoms one gets as a filter that hasn't been changed out but needs to be will give you... such as inability to reach maximum power.


    These are just my "comments"/guesses.

    If I were you I'd call the filter manufacturer tech support and see what their take is.
    They should know a lot more about how filter fineness effects life and flow, and should want to give you a straight scoop.

    Is it a K&N filter?
    http://www.knfilters.com/inline-filters.htm
      
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  • Re: 912ULS gas filter at 40 microns

    by » 11 years ago

    Don't use too fine a filter as it can produce back pressure in system. It takes pressure to drive fuel thru filter and the finer the filter element, the more pressure required for a given flow rate or the less fuel flow at a given pump pressure.
      
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  • Re: 912ULS gas filter at 40 microns

    by » 11 years ago

    A finer filter may or may not result in more flow resistance. Depends on the total area of the filter material and other characteristics of the filter material.
    Other than checking with the techies at the filter manufacturer trying it out and seeing what happens may be the only way to know.

    Al
      
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  • Re: 912ULS gas filter at 40 microns

    by » 11 years ago

    I would think most fuel filters today will flow plenty of fuel for our needs. Just from the nature of the beast who would build a standard fuel filter that could possible restrict fuel flow. Most filters should be able to flow a lot more volume than we need. Remember fuel filters are usually upstream so fuel isn't pressured through, but usually has a suction verses a pressure. They should be before a pump not after.

    Roger Lee
    LSRM-A & Rotax Instructor & Rotax IRC
    Tucson, AZ Ryan Airfield (KRYN)
    520-349-7056 Cell

      
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  • Re: 912ULS gas filter at 40 microns

    by » 11 years ago

    Thanks for all the great replies! I've settled on an Earl's 230206ERL filter that has an 85 micron screen. Here is a link to it. "Flow" rate is at 4 to 5 Gallons per MINUTE. I'll install in my RANS Coyote which has a gravity feed system. I'll check for 8.2 Gal per HOUR before the maiden flight.
    Thanks!

    http://www.summitracing.com/oh/parts/ear-230206erl/overview/
      
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