X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from smtpauth17.prod.mesa1.secureserver.net ([64.202.165.29] verified) by logan.com (CommuniGate Pro SMTP 5.3c3) with SMTP id 3991256 for flyrotary@lancaironline.net; Wed, 25 Nov 2009 16:40:25 -0500 Received-SPF: none receiver=logan.com; client-ip=64.202.165.29; envelope-from=aviator@stinsonvoyager.com Received: (qmail 7779 invoked from network); 25 Nov 2009 21:39:48 -0000 Received: from unknown (76.88.64.229) by smtpauth17.prod.mesa1.secureserver.net (64.202.165.29) with ESMTP; 25 Nov 2009 21:39:48 -0000 From: "Bill Monroe" To: "'Rotary motors in aircraft'" References: In-Reply-To: Subject: RE: [FlyRotary] Vacuum System Regulation Basics Date: Wed, 25 Nov 2009 13:39:37 -0800 Message-ID: <003601ca6e17$c969ae90$5c3d0bb0$@com> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0037_01CA6DD4.BB466E90" X-Mailer: Microsoft Office Outlook 12.0 Thread-Index: AcpuE3+8sHo9M8+ESpKBdQoMwAIWBwAA9vgA Content-Language: en-us This is a multi-part message in MIME format. ------=_NextPart_000_0037_01CA6DD4.BB466E90 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sounds like you really just need a smaller venturi. How many vacuum powered 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 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 following: I have a 9" venturi on side of fuselage - connected with a 3/8" hose, the suction gauge reads 9". This is too much for gyros, so I put a restrictor in the line expecting to get less vacuum - instead it goes to >10". 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'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 gauges, as any dust would get sucked out of cabin without passing through gauges. Jeff ------=_NextPart_000_0037_01CA6DD4.BB466E90 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

Sounds like you = really just need a smaller venturi. How many vacuum powered 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 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 = following:

I have a 9” = venturi on side of fuselage – connected with a 3/8” hose, the suction gauge = reads 9”. This is too much for gyros, so I put a restrictor in the line expecting to = get less vacuum – instead it goes to >10”. 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’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 gauges, as any dust would get = sucked out of cabin without passing through gauges.

Jeff

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