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Old 03-24-2021, 03:33 PM
bobnoffs bobnoffs is offline
Join Date: Jul 2012
Location: n. wi
Posts: 826
Default fuel filter micron sizing

from reading threads on this forum it seems that sizing the first filter downstream of the sump but before the pumps be 70 micron and the filter before the injectors be 30 micron.
my first filter is an aeromotive with a 100 micron screen and just before my injectors is a 20 micron. this 20 micron is a big can filter with a pleated lining. the can is probably 21/2 diameter, 31/2-4'' long.
this set up is for a 100 hp engine.
although my numbers aren't ideal, do i really need to change ?
Bob Noffs
n. wi.
dakota hawk/jab 3300 built and flying. sold 6/18.getting serious about the 12. in the hangar now as of 10/15/19
RV-12 kit as of 9/13
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Old 03-24-2021, 04:00 PM
BillL BillL is offline
Join Date: Sep 2007
Location: Central IL
Posts: 5,873
Default Check your pump specifications.

You will be ok if your pump can eat 99 micron particles. The 70 number is to protect the pump and specified by them. Your 20 would be good with plenty of capacity.

Lord Kelvin:
I often say that when you can measure what you are speaking about,
and express it in numbers, you know something about it; but when you
cannot measure it, when you cannot express it in numbers, your knowledge
is of a meager and unsatisfactory kind.
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Old 03-24-2021, 07:31 PM
12vaitor 12vaitor is offline
Join Date: Aug 2012
Location: Panama City, FL
Posts: 161

I recently changed my RV-12 design with dual fuel pumps from a single 10-micron Golan primary filter (tank outlet to fuel pump inlets) to an 85-micron filter on each pump inlet. The 10-micron was too fine and susceptible to clogging, as evidenced by a 12 psi fuel pressure drop 20 minutes after takeoff. Other options are 35-micron and 50-micron, the main point being to eliminate a single point failure if the filter clogs. The 10-micron final filter I am using is a large Professional Products 70160 in-line canister to keep stuff out of the injectors. TI Automotive recommends a 35-micron pre-filter for the GSL pumps, Performance recommends a 100-micron pre-filter before the pump.

Unlike other RVs, the -12 only has one fuel tank so you should consider downstream failure modes for filters and pumps. My final filter is still a single failure point that could be fixed with a pressure bypass filter setup or just adding a pressure sensor on the filter outlet/fuel rail side to monitor the pressure differential. I noted the -12iS with the dual pump setup has the same single pre-filter setup from the tank outlet that will take out both pumps if it clogs.

John Salak
RV-12 N896HS
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Old 03-25-2021, 06:38 AM
fdeppieri fdeppieri is offline
Join Date: Jun 2017
Location: Italy - Venice -
Posts: 38

Hi all,

I'm proceeding to the installation of the fuel system in my RV-10.
I adopt the SDS EFII system and I'm working inside the central tunnel.
I built a removable structure that keeps Andair duplex valve, the pump and the filter, that allows to mount all the items very easily out of the tunnel; on a second time the structure can be placed in the tunnel to complete the installation.
Optionally I'm evaluating to close the structure inside a steel box to isolate these critical items from the tunnel environment.

I adopted the Aerolab easy removable fuel filter at the bottom of the removable structure, but it is 50 micron filter instead 40 as provided by Ross of SDS EFII.
I asked him if it can be ok, and the answer was "...Shouldn't be a big deal going to 50. ".

I'm a little worries about. What do you think ?

Thanks a lot,
Francesco D.
RV10 - #41865
- Fuselage in progress -
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Old 03-25-2021, 07:53 AM
Nova RV Nova RV is offline
Join Date: Aug 2015
Location: Leesburg, VA
Posts: 531

FWIW Don at Airflow Performance recommends their 125 micron filter pre-pump.
Chris Moon
Leesburg, VA


RV-14A kit # 140243 (flying as of 11/18)
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Old 03-25-2021, 08:10 AM
Freemasm Freemasm is online now
Join Date: Nov 2017
Location: Orlando
Posts: 341

Don't guess or rely on anecdotal info. Determine the OEM of the pump, not the supplier, and review their official releases. It's more than micron rating. DeltaP versus flow, capacity/surface area, etc. should all be strongly adhered to. The same to true for the downstream filter. These requirements should be gleaned from your FI system OEM. I'd also avoid any potential temptation to significantly exceed any requirements; e.g. too fine a filtration can cause issues as already stated.

Last edited by Freemasm : 03-25-2021 at 08:48 AM.
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Old 03-25-2021, 09:31 AM
Steve Melton's Avatar
Steve Melton Steve Melton is offline
Join Date: Apr 2011
Location: Cincinnati, OH
Posts: 3,107

I use 74 micron before the pump and it's the large screen surface area size.
Steve Melton
Cincinnati, OH
RV-9A, Tip-up, Superior O-320, roller lifters, 160HP, WW 200RV, dual impulse slick mags, oil pressure = 65 psi, EGT = 1300F, flight hours = 900+ for all

Simplicity is the art in design.
I was born an airplane nut. I have no explanation for it.
My Artwork is freely given and published and cannot be patented.
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