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Date: Fri, 25 Feb 2011 16:36:36 -0500
From: Ernest Christley <echristley@att.net>
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To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: Fuel return line
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Rogers, Bob J. wrote:
> Raymond,
>=20
> =20
>=20
> For a high-pressure fuel pump that generates a large volume of fuel=20
> flow, a 1/4=93 return line seems a bit small to me.  If you attach a fu=
el=20
> pressure gauge to a =93T=94 midway in the =BC=94 return line and run fu=
el=20
> through your pump and out the return line (past the pressure gauge),=20
> when the return line is big enough to handle the flow, then you will se=
e=20
> almost no build up in pressure.  If the line is too small, then the=20
> inability of the fuel to easily escape through the return line will=20
> cause a build-up of pressure in the gauge.  The amount may be negligibl=
e=20
> or it may be a lot, depending on the force of the fuel.  Ideally, the=20
> pressure on the return line would be zero, or close to it.  Use a retur=
n=20
> line that generates little or no pressure on the fuel pump.
>=20
> =20
>=20

Better yet, just make the return line the same size as the feed line.  Sa=
ve money by not having to have more sizes on=20
hand, completely eliminate the return pressure problem AND simplify your =
life.

Better yet, put the regulator at the tank, and don't bring hot fuel back =
from the engine.  Once it goes pass the=20
firewall, the only way out is through the fiery furnace.

>=20
> -----------------------------------------------------------------------=
-
>=20
> *From:* Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] =

> *On Behalf Of *Raymond Lambert
> *Sent:* Friday, February 25, 2011 2:20 PM
> *To:* Rotary motors in aircraft
> *Subject:* [FlyRotary] Fuel return line
>=20
> =20
>=20
> /I am about to put /the fuel tank in my first wing. I have to weld a=20
> flange on it for the fuel return line. Anyone can tell me if a 1/4" fue=
l=20
> return line is large enough ????
>=20
> Raymond
>=20