Return-Path: Received: from ms-smtp-04.texas.rr.com ([24.93.47.43] verified) by logan.com (CommuniGate Pro SMTP 4.2b3) with ESMTP id 93600 for flyrotary@lancaironline.net; Thu, 27 May 2004 20:06:58 -0400 Received: from dell (cs6669241-190.austin.rr.com [66.69.241.190]) by ms-smtp-04.texas.rr.com (8.12.10/8.12.7) with SMTP id i4S06pt3012357 for ; Thu, 27 May 2004 19:06:55 -0500 (CDT) Message-ID: <00a601c44447$a3b79220$6401a8c0@austin.rr.com> From: "Bob Darrah" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: Fuel Pump Design Date: Thu, 27 May 2004 19:06:34 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_00A3_01C4441D.BA7CD4E0" 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 X-Virus-Scanned: Symantec AntiVirus Scan Engine This is a multi-part message in MIME format. ------=_NextPart_000_00A3_01C4441D.BA7CD4E0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable ----- Original Message -----=20 From: Haywire=20 To: Rotary motors in aircraft=20 Sent: Thursday, May 27, 2004 6:39 PM Subject: [FlyRotary] Re: Fuel Pump Design Haywire wrote: Hi Bob;=20 Most (all?) hi-press fuel pumps have a built in check valve so this = can be eliminated. Your transfer pump from the aux. tanks, I'm assuming = a Facet pump? In this case, while they don't guarantee no backflow, it = has been my experience that they hold pretty well, so a check valve = could be eliminated here as well.(snip) I would suggest you keep these checkvalves. Not to prevent backflow, = the pump will do that, but to prevent forward flow unless the pump is = turned on. The Facet pumps I have will flow forward whether they are on = or off. A checkvalve that requires just a little cracking pressure will = prevent forward flow. High pressure positive displacement pumps don't = have this problem. Bob Darrah ------=_NextPart_000_00A3_01C4441D.BA7CD4E0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
 
----- Original Message -----
From:=20 Haywire
Sent: Thursday, May 27, 2004 = 6:39=20 PM
Subject: [FlyRotary] Re: Fuel = Pump=20 Design
 
Haywire wrote:

Hi Bob;
Most = (all?)=20 hi-press fuel pumps have a built in check valve so this can be = eliminated.=20 Your transfer pump from the aux. tanks, I'm assuming a Facet pump? In = this=20 case, while they don't guarantee no backflow, it has been my = experience that=20 they hold pretty well, so a check valve could be eliminated here as=20 well.(snip)

I would suggest you keep these checkvalves.  = Not to=20 prevent backflow, the pump will do that, but to prevent forward flow = unless=20 the pump is turned on.  The Facet pumps I have will flow forward = whether=20 they are on or off.  A checkvalve that requires just a = little=20 cracking pressure will prevent forward flow. High pressure = positive=20 displacement pumps don't have this problem.

 

Bob Darrah

 

 

 

 

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