X-Virus-Scanned: clean according to Sophos on Logan.com
Return-Path: <marv@lancaironline.net>
Sender: <marv@lancaironline.net>
To:  lml@lancaironline.net
Date: Mon, 14 Oct 2013 08:14:11 -0400
Message-ID: <redirect-6530326@logan.com>
X-Original-Return-Path: <pjdmiller@gmail.com>
Received: from mail-vb0-f53.google.com ([209.85.212.53] verified)
  by logan.com (CommuniGate Pro SMTP 6.0.7)
  with ESMTPS id 6513186 for lml@lancaironline.net; Sat, 12 Oct 2013 19:54:20 -0400
Received-SPF: pass
 receiver=logan.com; client-ip=209.85.212.53; envelope-from=pjdmiller@gmail.com
Received: by mail-vb0-f53.google.com with SMTP id i3so3752313vbh.40
        for <lml@lancaironline.net>; Sat, 12 Oct 2013 16:53:47 -0700 (PDT)
MIME-Version: 1.0
X-Received: by 10.220.58.1 with SMTP id e1mr6951015vch.0.1381622027755; Sat,
 12 Oct 2013 16:53:47 -0700 (PDT)
Received: by 10.220.98.71 with HTTP; Sat, 12 Oct 2013 16:53:47 -0700 (PDT)
In-Reply-To: <list-6513153@logan.com>
References: <list-6513153@logan.com>
X-Original-Date: Sat, 12 Oct 2013 17:53:47 -0600
X-Original-Message-ID: <CAH20rPC_pDCuyF++Ot1pqHePaoBbYPHObbO1JG4sSHqUov_aTg@mail.gmail.com>
Subject: Re: [LML] Re: Removing vacuum pump? (LIVP)
From: Paul Miller <pjdmiller@gmail.com>
X-Original-To: Lancair Mailing List <lml@lancaironline.net>
Content-Type: multipart/alternative; boundary=001a11c2c7da2da5bf04e893f29e

--001a11c2c7da2da5bf04e893f29e
Content-Type: text/plain; charset=ISO-8859-1

If the pressure controller on the panel has rate of climb and cabin
altitude settings (like a Garrett), it likely uses the vacuum line to
modulate the outflow valves (pull them open).  That modulation is what
provides the signal to allow the cabin to climb or descend.   I don't know
what controller is in place but the vacuum is for cabin differential
control.  The squat switch is for ground use or emergency and simple opens
the outflow to a maximum.  In a typical situation, the outflow closes with
wheels up then the vacuum signal starts to open the valves to provide the
differential required to either climb or hold the cabin as set by the
controller.

If the vacuum is disconnected, I suspect you simply are running with a
fully closed outflow valve and the cabin pressure is an open loop with
whatever pressure is supplied from the firewall.  Does that sound about
right?

What I am missing is if there is no vacuum line then why install the
controller?  How does it control anything?  Those controllers can't be
cheap.


On 12 October 2013 17:00, jeffrey liegner <liegner@ptd.net> wrote:

>   The device might function better (although I can't prove that), but it
> is not necessary.  I recall that it is to help the valve move initially
> (and has no value after that first movement) and effect a seal early

--001a11c2c7da2da5bf04e893f29e
Content-Type: text/html; charset=ISO-8859-1
Content-Transfer-Encoding: quoted-printable

<div dir=3D"ltr">If the pressure controller on the panel has rate of climb =
and cabin altitude settings (like a Garrett), it likely uses the vacuum lin=
e to modulate the outflow valves (pull them open). =A0That modulation is wh=
at provides the signal to allow the cabin to climb or descend. =A0 I don&#3=
9;t know what controller is in place but the vacuum is for cabin differenti=
al control. =A0The squat switch is for ground use or emergency and simple o=
pens the outflow to a maximum. =A0In a typical situation, the outflow close=
s with wheels up then the vacuum signal starts to open the valves to provid=
e the differential required to either climb or hold the cabin as set by the=
 controller.<div>
<br></div><div>If the vacuum is disconnected, I suspect you simply are runn=
ing with a fully closed outflow valve and the cabin pressure is an open loo=
p with whatever pressure is supplied from the firewall. =A0Does that sound =
about right?</div>
<div><br></div><div>What I am missing is if there is no vacuum line then wh=
y install the controller? =A0How does it control anything? =A0Those control=
lers can&#39;t be cheap.<br><div class=3D"gmail_extra"><br><br><div class=
=3D"gmail_quote">
On 12 October 2013 17:00, jeffrey liegner <span dir=3D"ltr">&lt;<a href=3D"=
mailto:liegner@ptd.net" target=3D"_blank">liegner@ptd.net</a>&gt;</span> wr=
ote:<br><blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border=
-left:1px #ccc solid;padding-left:1ex">
=A0 The device might function better (although I can&#39;t prove that), but=
 it is not necessary. =A0I recall that it is to help the valve move initial=
ly (and has no value after that first movement) and effect a seal early=A0<=
/blockquote>
</div></div></div></div>

--001a11c2c7da2da5bf04e893f29e--