X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from EXHUB003-3.exch003intermedia.net ([207.5.74.110] verified) by logan.com (CommuniGate Pro SMTP 5.3c3) with ESMTPS id 3991798 for flyrotary@lancaironline.net; Thu, 26 Nov 2009 08:40:00 -0500 Received-SPF: none receiver=logan.com; client-ip=207.5.74.110; envelope-from=jwhaley@datacast.com Received: from EXVMBX003-5.exch003intermedia.net ([207.5.74.45]) by EXHUB003-3.exch003intermedia.net ([207.5.74.110]) with mapi; Thu, 26 Nov 2009 05:39:24 -0800 From: Jeff Whaley To: Rotary motors in aircraft Date: Thu, 26 Nov 2009 05:41:44 -0800 Subject: RE: [FlyRotary] Re: Vacuum System Regulation Basics Thread-Topic: [FlyRotary] Re: Vacuum System Regulation Basics Thread-Index: AcpuF+77VlG+KxcKT7+PojvSpptfmQAgPxRA Message-ID: References: In-Reply-To: Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: acceptlanguage: en-US Content-Type: multipart/alternative; boundary="_000_C03ABB0A7362B84BB53D544B3C305E0E0153A41BD66DEXVMBX0035e_" MIME-Version: 1.0 --_000_C03ABB0A7362B84BB53D544B3C305E0E0153A41BD66DEXVMBX0035e_ Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable That's what I thought too ... but spoke with a flight engineer AME last nig= ht and he says a 9" venture is minimum to run my 2 gauges 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 ... closest to venturi will give h= ighest reading. I need to take a good look at the plumbing to check/move location of the su= ction gauge. Jeff 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 Sounds like you really just need a smaller venturi. How many vacuum powere= d gauges are you running? Regulators usually go between the vacuum source and the rest of the system = but I can't recall ever seeing one used in a venturi system, usually only o= n vacuum pump equipped installations. 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 Can anyone explain the following: I have a 9" venturi on side of fuselage - connected with a 3/8" hose, the s= uction gauge reads 9". This is too much for gyros, so I put a restrictor i= n the line expecting to get less vacuum - instead it goes to >10". This wo= uld 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'm getting the feeling that a regulator is actually a "controlled leak" - = 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 --_000_C03ABB0A7362B84BB53D544B3C305E0E0153A41BD66DEXVMBX0035e_ Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

That’s what I thou= ght too … but spoke with a flight engineer AME last night and he says a 9” vent= ure is minimum to run my 2 gauges AH and DG.

He says the high reading= is due to the location of the suction gauge in relationship to the venturi and instruments … closest to venturi will give highest reading.

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

Jeff <= /p>

=

From: Rotary motors= in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Bill Monr= oe
Sent: Wednesday, November 25, 2009 4:40 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Vacuum System Regulation Basics<= /span>

Sounds like you really j= ust need a smaller venturi. How many vacuum powered gauges are you running?

=

Regulators usually go be= tween the vacuum source and the rest of the system but I can’t recall ever seeing one used in a venturi system, usually only on vacuum pump equipped installations.

=

From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Jeff Whaley
Sent: Wednesday, November 25, 2009 1:11 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Vacuum System Regulation Basics

Can anyone explain the foll= owing:

I have a 9” venturi o= n side of fuselage – connected with a 3/8” hose, the suction gauge rea= ds 9”. This is too much for gyros, so I put a restrictor in the li= ne expecting to get less vacuum – instead it goes to >10”. = ; This would imply that if hose was larger, vacuum would be less.<= /p>

If I was to install a regul= ator should it go between venturi and gauges? or after gauges between them and filter?

I’m getting the feeli= ng that a regulator is actually a “controlled leak” – adjusted by= a needle-valve? True or False?

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

Jeff

--_000_C03ABB0A7362B84BB53D544B3C305E0E0153A41BD66DEXVMBX0035e_--