X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from mail04.syd.optusnet.com.au ([211.29.132.185] verified) by logan.com (CommuniGate Pro SMTP 4.3.4) with ESMTPS id 1002234 for flyrotary@lancaironline.net; Tue, 14 Jun 2005 18:22:55 -0400 Received-SPF: none receiver=logan.com; client-ip=211.29.132.185; envelope-from=lendich@optusnet.com.au Received: from george (d220-236-249-4.dsl.nsw.optusnet.com.au [220.236.249.4]) by mail04.syd.optusnet.com.au (8.12.11/8.12.11) with SMTP id j5EMM5MX019484 for ; Wed, 15 Jun 2005 08:22:06 +1000 Message-ID: <002a01c57130$3d6e12c0$04f9ecdc@george> From: "George Lendich" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: fuel pump mounting Date: Wed, 15 Jun 2005 08:27:24 +1000 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0027_01C57184.0ECF3710" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1106 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 This is a multi-part message in MIME format. ------=_NextPart_000_0027_01C57184.0ECF3710 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable The group keeps getting the same questions from people - which I know is = normal and it's good to re-establish the points mentioned. However a list of best practices AND THE REASONS FOR THEM could make the = process of learning and responding much simpler. MO - FWIW George ( down under) Can the inlet be fed from a tube=20 that goes into a tank close to the bottom 1.5" but is bent down in a = 90=20 degree bend? The sump is lower than the tanks and the pumps would be = at the=20 level of the bottom of the sump. My concern is how much of a "hump" in = the=20 plumbing will the pump tolerate? Thanks for any help. Joe Berki Joe; A "hump" in the plumbing is not necessarily and issue, but your = situation as I understand it is questionable. The head at the pump = inlet (neglecting line losses) is the difference between the level of = the surface of the fuel and the pump inlet. Any "hump" should not go = higher than the surface of the fuel when the fuel is at its lowest = point. If I understand your case correctly, you would have to rely on = "siphoning" to get gravity feed from your tank below the level of where = the tube exits the tank; or if you are pumping out of the tank, the pump = could "normally" draw that last 1.5" of fuel out, but in either case I'd = say this is not a desirable condition, as it will take a negative = pressure, however slight, to get it out. With 100LL it would probably = not be a problem as it is formulated with a higher vapor pressure than = mogas. The other issue with a high spot in the plumbing is the potential for = trapped air. When you fill from an empty condition there will be air = trapped at the high point. That's not necessarily an issue; if it has = some place to go, like the sump tank with a vent, and enough head to = push it through. If you partially filled your tank with air trapped in = the line you may get no flow. The supply line from the tank needs to go steadily down hill, either = to a pump or gravity feed to a sump tank. Any air in the line should be = able to migrate back to the tank. FWIW - I don't know the details of your system, so can only speak in = generalities. Al ------=_NextPart_000_0027_01C57184.0ECF3710 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

The group keeps getting the same = questions from=20 people - which I know is normal and it's good to re-establish the points = mentioned.

However a list of best practices = AND THE=20 REASONS FOR THEM could make the process of learning and = responding much=20 simpler.

MO - FWIW

George ( down under)

Can the inlet be fed from a tube =

that goes into a tank close to the bottom = 1.5" but is=20 bent down in a 90

degree bend? The sump is lower than the = tanks and the=20 pumps would be at the

level of the bottom of the sump. My concern = is how=20 much of a "hump" in the

plumbing will the pump tolerate? = Thanks for any=20 help.

Joe Berki

Joe;

A = =93hump=94 in the=20 plumbing is not necessarily and issue, but your situation as I = understand it=20 is questionable. The head at the pump inlet (neglecting line = losses) is=20 the difference between the level of the surface of the fuel and the = pump=20 inlet. Any =93hump=94 should not go higher than the surface of = the fuel when=20 the fuel is at its lowest point.

If I = understand=20 your case correctly, you would have to rely on =93siphoning=94 to get = gravity feed=20 from your tank below the level of where the tube exits the tank; or if = you are=20 pumping out of the tank, the pump could =93normally=94 draw that last = 1.5=94 of fuel=20 out, but in either case I=92d say this is not a desirable condition, = as it will=20 take a negative pressure, however slight, to get it out. With = 100LL it=20 would probably not be a problem as it is formulated with a higher = vapor=20 pressure than mogas.

The = other issue=20 with a high spot in the plumbing is the potential for trapped air. = When=20 you fill from an empty condition there will be air trapped at the=20 high = point.=20 That=92s not necessarily an issue; if it has some place to go, = like the=20 sump tank with a vent, and enough head to push it through. If = you=20 partially filled your tank with air trapped in the line you may get no = flow.

The = supply line=20 from the tank needs to go steadily down hill, either to a pump or = gravity feed=20 to a sump tank. Any air in the line should be able to migrate back to = the=20 tank.

FWIW - I = don=92t=20 know the details of your system, so can only speak in=20 generalities.

Al

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