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Put a pressure gage between tank and pump. This will measure how much
safety margin you have. It's that pressure drop at pump inlet that's your risk
item. Compare that pressure to results from Hodges fuel tester and wham, you
know exactly how close you are. This is a key safety concept...don't let
yourself describe fuel system as good or bad....measure it!
I know guys who used clear fuel lines so they could see the fuel turn to
vapor, but you only see things when it's too late. Pressure gage tells you how
far your design is from vapor lock. That way you know you will be safe when
other factors affect vapor point. Like pump temp, fuel type, flight
attitude.
All filter screens that get plugged are from one cause....using vacuum
cleaner to remove debris. Ordinary vacuum cleaner displaces too much air. It
causes 80% of the debris near nozzle to shoot off to corners of tank. If you
just put duct tape over most of the nozzle, then you have zero risk of
debris.
Glad you are concerned about pressure drop at inlet. You definitely don't
want to add fine filter there.
I just added wet fuel pumps to my plane. One of the safest approaches you
can use. Details on my web site.
Ed,
You stated that you use Facet pumps, I suppose these are
before the in-line filter. My concern about using the filters before the efi
fuel pump is that there would be more flow restriction. Since I will be using
gravity fed sump tank (5-6 inch elevation difference and I don't want to
pressurize the sump tank), that vaporization could occur; hence I am still
thinking of a large surface screen in the sump tank (already have screen wire
over the strake tank outlets) to catch small stuff that could shorten pump
life, not necessarily plug up the pump. MSD claims to be able to handle small
particles better than the competition. Thinking also of putting in a sight
glass (Plexiglas) to observe tank behavior and screen condition. Can Plexiglas
hold up to auto gas? Oh yes, the sump tank will have a water
catch sub-sump.
Wendell (hope I'm making sense)
I have opened up my coarse filter 6 times in 10
years. First time had some small fragments of sealant used to close
the tank. The next 5 times nothing. Of course, a lot will depend
on type of tank and quality of fuel going into the tanks.
I replace the EFI filters at each conditional
inspection, cut the old ones open and have never found anything in them
either. But, I do use 100LL aircraft quality gasoline - almost
exclusively..
ED
----- Original Message -----
Sent: Sunday, September 09, 2007 4:00
PM
Subject: [FlyRotary] Re: need
help
Thanks Ed,
How often do you have to clean the
filter?
Wendell
I have a fine wire mesh filter in an aluminum
housing with An-6 fittings on each end just before the fuel enters my
header tank.. You can unscrew one end to clean the mesh.
However, been too long ago and I find I never logged the part number on
my fuel data sheet.
But, here are the specific part numbers I use for
the EFI filters
Fuel Filters: OEM Auto Fuel Injector Fuel Filters (Two in
Parallel)
Type: AC GF - 481 Pkg: 25056052 OEM:25055129 (or
equivalent)
Fittings: 3/8 Saginaw to AN6 Adapter, "O" ring required
Ed
----- Original Message -----
Sent: Saturday, September 08,
2007 10:18 PM
Subject: [FlyRotary] Re: need
help
Thanks Rob and Ed for the replys on the MSD
fuel pumps.
Now; what kind of filter do you have
ahead of the pump? I'm thinking of using some fine mesh screen
to make a filter inside the sump tank. It will be hard to
service but believe that one will prolong pump life and possibly.
stop a particle that could interupt fuel flow. What size mesh
is recommended?
Wendell
I have been using the MSD 2225 for
about 20 hour with no problem so far. Plenty of fuel pressure. Only
problem is that it is not threaded so I had to use the barbed
nipples that come with the pump. How bad can that be?
Robert Bollinger
FM1099
MUM
Fairfield IA 52557
(641)472-7000 ex2068
(641)919-3213
cell
rob@mum.edu
-al wick
Cozy IV powered by Turbo Subaru
3.0R with variable valve lift and cam timing.
Artificial intelligence in
cockpit, N9032U 240+ hours from Portland, Oregon
Glass panel design, Subaru
install, Prop construct, Risk assessment
info:
http://www.maddyhome.com/canardpages/pages/alwick/index.html
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