X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from web83904.mail.sp1.yahoo.com ([69.147.92.103] verified) by logan.com (CommuniGate Pro SMTP 5.3c3) with SMTP id 3991853 for flyrotary@lancaironline.net; Thu, 26 Nov 2009 09:26:55 -0500 Received-SPF: none receiver=logan.com; client-ip=69.147.92.103; envelope-from=delta11xd@att.net Received: (qmail 76124 invoked by uid 60001); 26 Nov 2009 14:26:20 -0000 Message-ID: <384888.75824.qm@web83904.mail.sp1.yahoo.com> X-YMail-OSG: u5AfU7gVM1nkb2F2uOBEX0v1KtgljYMhXiQu0H1SZsmctKSmRqOvdohxYoZzQ5TDY1KT0Gf594zixq7BEzcjvup2h1jVNlueA_uUZshDD0MK4QapKy4rNZOi.i9wHwCvUHqXGS0hiPw4ZdUwFD6Z7ZpTsVi8HvJ3xN1QOUzpTK5CMrp6Cc7.HLzNWh7INT9LlZ6B.GQ3EoM6NNUvaYlwW26PeNBIRZFTCQnmvMJNgly3GNRAX8KJGOlxSRuJRje.F_PmIHGGwFlTCRgR197YdTgiPTOkZalPsHK1ZY7DaNLPH2a0npAfSc84OFZa2aavbF8LpzfAGfXffz2_spo.XeM- Received: from [75.24.79.206] by web83904.mail.sp1.yahoo.com via HTTP; Thu, 26 Nov 2009 06:26:20 PST X-Mailer: YahooMailClassic/8.1.6 YahooMailWebService/0.8.100.260964 Date: Thu, 26 Nov 2009 06:26:20 -0800 (PST) From: James Maher Subject: Re: [FlyRotary] Re: Vacuum System Regulation Basics To: Rotary motors in aircraft In-Reply-To: MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="0-857114842-1259245580=:75824" --0-857114842-1259245580=:75824 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Jeff, If I recall correctly most gyro instruments have a port for connecting the = suction gauge so that you can read the vacuum right at the instrument. That= is where I connected mine. The restrictor goes between the vacuum source (pump or venturi)=C2=A0and th= e gyro instrument that you are trying to reduce the FLOW to. It is a flow r= estrictor not a vacuum restrictor. The gyro instrument spin speed is govern= ed by volume=C2=A0or flow of air not just the difference in pressure. =C2=A0 =C2=A0 Jim --- On Thu, 11/26/09, Jeff Whaley wrote: From: Jeff Whaley Subject: [FlyRotary] Re: Vacuum System Regulation Basics To: "Rotary motors in aircraft" Date: Thursday, November 26, 2009, 8:41 AM That=E2=80=99s what I thought too =E2=80=A6 but spoke with a flight enginee= r AME last night and he says a 9=E2=80=9D venture is minimum to run my 2 ga= uges AH and DG. He says the high reading is due to the location of the suction gauge in rel= ationship to the venturi and instruments =E2=80=A6 closest to venturi will = give highest reading. I need to take a good look at the plumbing to check/move location of the su= ction gauge.=20 Jeff=20 =C2=A0 From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Beh= alf Of Bill Monroe Sent: Wednesday, November 25, 2009 4:40 PM To: Rotary motors in aircraft Subject: [FlyRotary] Re: Vacuum System Regulation Basics =C2=A0 Sounds like you really just need a smaller venturi.=C2=A0 How many vacuum p= owered gauges are you running? =C2=A0 Regulators usually go between the vacuum source and the rest of the system = but I can=E2=80=99t recall ever seeing one used in a venturi system, usuall= y only on vacuum pump equipped installations. =C2=A0 From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Beh= alf Of Jeff Whaley Sent: Wednesday, November 25, 2009 1:11 PM To: Rotary motors in aircraft Subject: [FlyRotary] Vacuum System Regulation Basics =C2=A0 Can anyone explain the following: I have a 9=E2=80=9D venturi on side of fuselage =E2=80=93 connected with a = 3/8=E2=80=9D hose, the suction gauge reads 9=E2=80=9D.=C2=A0 This is too mu= ch for gyros, so I put a restrictor in the line expecting to get less vacuu= m =E2=80=93 instead it goes to >10=E2=80=9D.=C2=A0 This would imply that if= hose was larger, vacuum would be less. If I was to install a regulator should it go between venturi and gauges? or= after gauges between them and filter? I=E2=80=99m getting the feeling that a regulator is actually a =E2=80=9Ccon= trolled leak=E2=80=9D =E2=80=93 adjusted by a needle-valve? True or False? If True, it would make sense to put a controlled leak between venturi and g= auges, as any dust would get sucked out of cabin without passing through ga= uges. Jeff=20 =C2=A0 --0-857114842-1259245580=:75824 Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: quoted-printable
Jeff,
If I recall correctly most gyro instruments have a port for connecting= the suction gauge so that you can read the vacuum right at the instrument.= That is where I connected mine.
The restrictor goes between the vacuum source (pump or venturi) a= nd the gyro instrument that you are trying to reduce the FLOW to. It is a f= low restrictor not a vacuum restrictor. The gyro instrument spin speed is g= overned by volume or flow of air not just the difference in pressure.<= /DIV>
 
 
Jim

--- On Thu, 11/26/09, Jeff Whaley <jwhaley@datacas= t.com> wrote:

From: Jeff Whaley <jwhaley@datacast.com>Subject: [FlyRotary] Re: Vacuum System Regulation Basics
To: "Rotary mo= tors in aircraft" <flyrotary@lancaironline.net>
Date: Thursday, No= vember 26, 2009, 8:41 AM

That=E2=80=99s what I t= hought too =E2=80=A6 but spoke with a flight engineer AME last night and he= says a 9=E2=80=9D venture is minimum to run my 2 gauges AH and DG.<= /DIV>

He says the high readin= g is due to the location of the suction gauge in relationship to the ventur= i and instruments =E2=80=A6 closest to venturi will give highest reading.

I need to take a good l= ook at the plumbing to check/move location of the suction gauge.

Jeff

 

From: Rotary motors in aircraft [mailto:flyrotary@la= ncaironline.net] On Behalf Of Bill Monroe
Sent: Wednesday,= November 25, 2009 4:40 PM
To: Rotary motors in aircraft
Su= bject: [FlyRotary] Re: Vacuum System Regulation Basics

 

Sounds like you really = just need a smaller venturi.  How many vacuum powered gauges are you r= unning?

 

Regulators usually go b= etween the vacuum source and the rest of the system but I can=E2=80=99t rec= all ever seeing one used in a venturi system, usually only on vacuum pump e= quipped installations.

 

From: Rotary motors in= aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Jeff Wha= ley
Sent: Wednesday, November 25, 2009 1:11 PM
To: Rota= ry motors in aircraft
Subject: [FlyRotary] Vacuum System Regulati= on Basics

 

Can anyone explain the fo= llowing:

I have a 9=E2=80=9D ventu= ri on side of fuselage =E2=80=93 connected with a 3/8=E2=80=9D hose, the su= ction gauge reads 9=E2=80=9D.  This is too much for gyros, so I put a = restrictor in the line expecting to get less vacuum =E2=80=93 instead it go= es to >10=E2=80=9D.  This would imply that if hose was larger, vacu= um would be less.

If I was to install a reg= ulator should it go between venturi and gauges? or after gauges between the= m and filter?

I=E2=80=99m getting the f= eeling that a regulator is actually a =E2=80=9Ccontrolled leak=E2=80=9D =E2= =80=93 adjusted by a needle-valve? True or False?

If True, it would make se= nse to put a controlled leak between venturi and gauges, as any dust would = get sucked out of cabin without passing through gauges.

Jeff

 <= /BLOCKQUOTE>

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