Return-Path: Received: from fed1rmmtao05.cox.net ([68.230.241.34] verified) by logan.com (CommuniGate Pro SMTP 4.2) with ESMTP id 360147 for flyrotary@lancaironline.net; Tue, 10 Aug 2004 16:25:31 -0400 Received-SPF: none receiver=logan.com; client-ip=68.230.241.34; envelope-from=ALVentures@cox.net Received: from BigAl ([68.107.116.221]) by fed1rmmtao05.cox.net (InterMail vM.6.01.03.02.01 201-2131-111-104-103-20040709) with ESMTP id <20040810202453.YJXU14278.fed1rmmtao05.cox.net@BigAl> for ; Tue, 10 Aug 2004 16:24:53 -0400 From: "Al Gietzen" To: "'Rotary motors in aircraft'" Subject: RE: [FlyRotary] Re: returnless fuel system Date: Tue, 10 Aug 2004 13:24:56 -0700 Message-ID: <000001c47f18$1a339fb0$6400a8c0@BigAl> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0001_01C47EDD.6DD4C7B0" X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook, Build 10.0.6626 Importance: Normal In-Reply-To: X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1165 This is a multi-part message in MIME format. ------=_NextPart_000_0001_01C47EDD.6DD4C7B0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Subject: [FlyRotary] Re: returnless fuel system =20 Al, I don't believe that what I am seeing is mostly vapor (although = there is possibly some). If your theory is correct then lowering the pressure at = the regulator would decrease the pressure drop and less vapor would be made = and the return flow would decrease. This is opposite what I have found. Dave; =20 I didn't mean to infer "mostly" vapor just "some" bubbles. I recall a conversation with someone (maybe Greg at GRT) and was told bubbles, or pulsations from the pump if located just downstream, will cause high readings. You're right about the effects of regulator pressure; so I = don't know. It could also be your pumps pump more and that the readings are correct. I know Tracy has sold different pumps at different times. =20 Also, even if it is mostly bubbles (foam), there is still 40-80 gal/hr = of something going through that return line so it should be big enough to handle it. =20 From what I've heard, there are likely "some" bubbles. I am aware of a = case where the bubbles were observed in a clear walled tube used for the = return line. One guy with a Subie on a Velocity had trouble with foam coming = out of the vent line from the sump tank. I think he added a section of = large diameter tube where it could condense. I'm hoping not to see that, and = will keep pump #2 in backup status. My circuit diagram still shows pump 2 switched on by a pressure switch which closes on low fuel pressure, but = I'm have trouble finding the pressure switch for gasoline. They are = specified for oil, or for coolant. =20 =20 Al =20 ------=_NextPart_000_0001_01C47EDD.6DD4C7B0 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Message

Subject: [FlyRotary] Re: returnless fuel system

 

Al, I don't = believe that what I am seeing is mostly vapor (although there is possibly = some).  If your theory is correct then lowering the pressure at the regulator would decrease the pressure drop and less vapor would be made and the return = flow would decrease.  This is opposite what I have found.

Dave;

 <= /font>

I = didn’t mean to infer “mostly” vapor just “some” bubbles.  = I recall a conversation with someone (maybe Greg at GRT) and was told = bubbles, or pulsations from the pump if located just downstream, will cause high = readings.  You’re right about the effects of regulator pressure; so I don’t = know.  It could also be your pumps pump more and that the readings are = correct.  I know Tracy has sold different pumps at different = times.

 

Also, even if it = is mostly bubbles (foam), there is still 40-80 gal/hr of something going = through that return line so it should be big enough to handle = it.

 

From what = I’ve heard, there are likely “some” bubbles.  I am aware of = a case where the bubbles were observed in a clear walled tube used for the = return line.  One guy with a Subie on a Velocity had trouble with foam coming out of = the vent line from the sump tank.  I think he added a section of large = diameter tube where it could condense.  I’m hoping not to see that, = and will keep pump #2 in backup status.  My circuit diagram still shows pump = 2 switched on by a pressure switch which closes on low fuel pressure, but I’m = have trouble finding the pressure switch for gasoline.  They are = specified for oil, or for coolant. 

 <= /font>

Al

=

 

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