Return-Path: Sender: (Marvin Kaye) To: lml@lancaironline.net Date: Wed, 26 May 2004 23:58:03 -0400 Message-ID: X-Original-Return-Path: Received: from wind.imbris.com ([216.18.130.7] verified) by logan.com (CommuniGate Pro SMTP 4.2b3) with ESMTP id 92083 for lml@lancaironline.net; Wed, 26 May 2004 23:17:25 -0400 Received: from regandesigns.com (cda131-147.imbris.com [216.18.131.147]) by wind.imbris.com (8.11.7/8.11.6) with ESMTP id i4R3HCp39475; Wed, 26 May 2004 20:17:12 -0700 (PDT) X-Original-Message-ID: <40B55DC0.9060804@regandesigns.com> Disposition-Notification-To: Brent Regan X-Original-Date: Wed, 26 May 2004 20:17:20 -0700 From: Brent Regan User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.4) Gecko/20030624 Netscape/7.1 (ax) X-Accept-Language: en-us, en MIME-Version: 1.0 X-Original-To: Carl Cadwell , Lancair Mailing List Subject: Re: Door pump stays on at altitude References: <63D0A1D8F168684F8502C4B8A229D7911691F3@DEWEY2.Cadwell.cadwell.com> In-Reply-To: <63D0A1D8F168684F8502C4B8A229D7911691F3@DEWEY2.Cadwell.cadwell.com> Content-Type: multipart/alternative; boundary="------------010304030206030806020804" This is a multi-part message in MIME format. --------------010304030206030806020804 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 8bit Carl: You are absolutely right. The pump inlet will see cabin pressure NOT outside pressure. My brain must not have been up to operating temperature... What I should have said was that at a CABIN altitude of 12,000 the pump will only be able to make 2/3 the pressure it makes at sea level so the switch pressure should be set to the lesser of manufacturers maximum pressure for the seal OR 1/2 of the pumps maximum pressure at sea level. 15 to 20 PSI seems like the right range. Regards Brent Regan Carl Cadwell wrote: > Brent, > > I understand from the factory that the pump is to be set for 20#. > As I recall it will pump a maximum of about 30#. Setting this for ¼ > of the sea level pressure is 7-8#. > > > > I am also not clear what this has to do with the FL280 being 1/3 of > sea level pressure as the pump is on the inside of the pressure vessel. > > > > Am I missing something? > > > > --------------010304030206030806020804 Content-Type: text/html; charset=us-ascii Content-Transfer-Encoding: 7bit Carl:

You are absolutely right. The pump inlet will see cabin pressure NOT outside pressure. My brain must not have been up to operating temperature...

What I should have said was that at a CABIN altitude of 12,000 the pump will only  be able to make 2/3 the pressure it makes at sea level so the switch pressure should be set to the lesser of manufacturers maximum pressure for the seal OR 1/2 of the pumps maximum pressure at sea level. 15 to 20 PSI seems like the right range.

Regards
Brent Regan

Carl Cadwell wrote:

Brent,

I understand from the factory that the pump is to be set for 20#. 
As I recall it will pump a maximum of about 30#.  Setting this for ¼ of the sea level pressure is 7-8#.

 

I am also not clear what this has to do with the FL280 being 1/3 of sea level pressure as the pump is on the inside of the pressure vessel.

 

Am I missing something?

 


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