X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from imr-da01.mx.aol.com ([205.188.105.143] verified) by logan.com (CommuniGate Pro SMTP 6.0.2) with ESMTP id 6114258 for lml@lancaironline.net; Sun, 10 Mar 2013 10:30:27 -0400 Received-SPF: pass receiver=logan.com; client-ip=205.188.105.143; envelope-from=vtailjeff@aol.com Received: from mtaomg-ma05.r1000.mx.aol.com (mtaomg-ma05.r1000.mx.aol.com [172.29.41.12]) by imr-da01.mx.aol.com (Outbound Mail Relay) with ESMTP id CA9FF1C000071 for ; Sun, 10 Mar 2013 10:29:52 -0400 (EDT) Received: from core-mnb003b.r1000.mail.aol.com (core-mnb003.r1000.mail.aol.com [172.29.106.137]) by mtaomg-ma05.r1000.mx.aol.com (OMAG/Core Interface) with ESMTP id A2890E000087 for ; Sun, 10 Mar 2013 10:29:52 -0400 (EDT) References: To: lml@lancaironline.net Subject: Re: [LML] Re: Pressurization In-Reply-To: X-MB-Message-Source: WebUI MIME-Version: 1.0 From: vtailjeff@aol.com X-MB-Message-Type: User Content-Type: multipart/alternative; boundary="--------MB_8CFEBB2DC697878_12D8_691BC_webmailstg-m01.sysops.aol.com" X-Mailer: AOL Webmail 37547-STANDARD Received: from 24.107.65.42 by webmailstg-m01.sysops.aol.com (64.12.225.53) with HTTP (WebMailUI); Sun, 10 Mar 2013 10:29:51 -0400 Message-Id: <8CFEBB2DC5D9193-12D8-20D99@webmailstg-m01.sysops.aol.com> X-Originating-IP: [24.107.65.42] Date: Sun, 10 Mar 2013 10:29:52 -0400 (EDT) x-aol-global-disposition: G DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mx.aol.com; s=20121107; t=1362925792; bh=uBpbL463lN5mqIOgTPsxGU0phf2Wz/pzn5LNZvI+aL4=; h=From:To:Subject:Message-Id:Date:MIME-Version:Content-Type; b=AnlvbikrlnyUH8Mk/6NqNJhf36TJZpaevZtjpK53+4FGRbXsch1OySAMUwnWJIOMR sWY5qcqFZ1b2kRwifUL+ckl4jHQvibUkQ8Q6TtcCBxk7ocM+RgeJOqIMDDDCfEHbg3 49kOXMz5V8YmmyNC7oI7boJ/bkcZsFUXumSVVAE4= X-AOL-SCOLL-SCORE: 0:2:501834144:93952408 X-AOL-SCOLL-URL_COUNT: 0 x-aol-sid: 3039ac1d290c513c98e01a11 This is a multi-part message in MIME format. ----------MB_8CFEBB2DC697878_12D8_691BC_webmailstg-m01.sysops.aol.com Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" John, You need a cabin pressure controller with an integrated cabin altimeter. Se= nd a picture of what you have. Jeff Edwards -----Original Message----- From: John Barrett <2thman1@gmail.com> To: lml Sent: Sun, Mar 10, 2013 9:12 am Subject: [LML] Re: Pressurization Pete, Thanks for the info. I do not have a cabin altimeter inst on my panel and = I'm pretty sure neither Cheltons nor the VP 200 can be configured for this = data. Yes, I would appreciate borrowing the tools you have. I would be happy to = pay shipping and a rental fee to help defray your acquisition costs for any= thing that helps. John Barrett 243 Old Oak Bay Rd Port Hadlock, WA 98339 3603011066 Sent from my iPad On Mar 9, 2013, at 9:18 AM, "pete@leapfrogventures.com" wrote: John, =20 I assume you are adding a cabin altimeter to your instrument panel? It rea= ds out both the cabin differential in psi and the cabin altitude. It is a = must have IMHO to monitor and prevent cabin over-pressurization. It is the= only test instrument needed for calibrating the Dukes and sealing the cabi= n. =20 I know that there is an overpressure valve that mounts next to the Dukes. = However, my Dukes head was not working properly during testing and was not = opening. The overpressure valve was no match for the amount of pressurized= air coming in the cabin, and the pressure quickly went over 6.5 psi before= I was able to do a manual dump. If you look at the teeny size of the over= pressure valve and compare that to the volume of pressurized air coming int= o the cabin on climb-out, you will quickly come to the conclusion that it p= rovides inadequate over pressurization protection. =20 I think you are using a G900 like me. It has an annunciator input called C= ABIN ALTITUDE. I connected that annunciator to a pressure switch set to 6 = psi that compares the pressure in the cabin to the pressure under the floor= in the baggage compartment (where the switch is mounted). In case the Duk= es valve fails and the cabin pressure rises too high, at least I will get s= ome notice (see note above about not depending on the manual vent valve). =20 I do have a digital differential manometer that measures PSI you are welcom= e to borrow. I used it to calibrate the overpressure valve that mounts nex= t to the Dukes (I set it to 6psi). I built a plenum from a large plastic f= ood container that you can pressurize with a compressor (carefully) that yo= u can borrow as well. =20 Pete =20 From: John Barrett [mailto:jbarrett@carbinge.com]=20 Sent: Friday, March 08, 2013 5:11 AM To: lml@lancaironline.net Subject: Pressurization =20 I didn=E2=80=99t think I=E2=80=99d need help with measurement issues, but I= =E2=80=99m hitting some stone walls. =20 I have a pocket altimeter I thought I=E2=80=99d use but wonder if it will h= ave a stop on negative altitude. Also I went online to see how to convert = altitude differential to PSID. Not much luck. The one site I found had co= nversion formulae that don=E2=80=99t seem correct. It lists a correlation = 1=E2=80=9D of mercury to 1,000 feet of altitude and that should be ok. It = then goes on to list a .49 conversion factor to get from inches of mercury = to psi. =20 =20 My calculations show that at a service ceiling of FL290 the altitude differ= ence to 10,000 foot cabin alt is 19,000 feet. .49 times this difference is= about 9.5 PSID. That=E2=80=99s WAY higher than the 5.0 PSI we=E2=80=99re = supposed to be seeing in the LIVP at FL 290. I had hoped to test to about = 6 PSI. =20 Short of an altimeter that allows negative readings all the way to somethin= g over 19K and a formula that works, the only other instrument I can think = of is a gauge that reads psi. I found some online that sell for from a cou= ple hundred bucks to $450 or so. They all appeared to be set up for plumbi= ng into a pipe system and I don=E2=80=99t know if they would read correctly= if placed inside the cockpit.=20 =20 How have you IVP builders out there gone about getting measurements when se= aling up the pressure vessel? =20 Thanks, =20 John Barrett, CEO Leading Edge Composites PO Box 428 Port Hadlock, WA 98339 =20 www.carbinge.com =20 ----------MB_8CFEBB2DC697878_12D8_691BC_webmailstg-m01.sysops.aol.com Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset="utf-8"
John,
 
You need a cabin pressure controller with an integrated cabin altimete= r. Send a picture of what you have.
 
Jeff Edwards


= -----Original Message-----
From: John Barrett <2thman1@gmail.com>
To: lml <lml@lancaironline.net>
Sent: Sun, Mar 10, 2013 9:12 am
Subject: [LML] Re: Pressurization

Pete,

Thanks for the info.  I do not have a cabin altimeter inst on my = panel and I'm pretty sure neither Cheltons nor the VP 200 can be configured= for this data.

Yes, I would appreciate borrowing the tools you have.  I would be= happy to pay shipping and a rental fee to help defray your acquisition cos= ts for anything that helps.

John Barrett
243 Old Oak Bay Rd
Port Hadlock, WA 98339
3603011066

Sent from my iPad


On Mar 9, 2013, at 9:18 AM, "p= ete@leapfrogventures.com" <pete@leapfrogventures.com> wrote:

John,
 
I assume you are addi= ng a cabin altimeter to your instrument panel?  It reads out both the = cabin differential in psi and the cabin altitude.  It is a must have I= MHO to monitor and prevent cabin over-pressurization.  It is the only = test instrument needed for calibrating the Dukes and sealing the cabin.
 
I know that there is = an overpressure valve that mounts next to the Dukes.  However, my Duke= s head was not working properly during testing and was not opening.  T= he overpressure valve was no match for the amount of pressurized air coming= in the cabin, and the pressure quickly went over 6.5 psi before I was able= to do a manual dump.  If you look at the teeny size of the overpressu= re valve and compare that to the volume of pressurized air coming into the = cabin on climb-out, you will quickly come to the conclusion that it provide= s inadequate over pressurization protection.
 
I think you are using= a G900 like me.  It has an annunciator input called CABIN ALTITUDE.&n= bsp; I connected that annunciator to a pressure switch set to 6 psi that co= mpares the pressure in the cabin to the pressure under the floor in the bag= gage compartment (where the switch is mounted).  In case the Dukes val= ve fails and the cabin pressure rises too high, at least I will get some no= tice (see note above about not depending on the manual vent valve).<= /div>
 
I do have a digital d= ifferential manometer that measures PSI you are welcome to borrow.  I = used it to calibrate the overpressure valve that mounts next to the Dukes (= I set it to 6psi).  I built a plenum from a large plastic food contain= er that you can pressurize with a compressor (carefully) that you can borro= w as well.
 
Pete
 
Fr= om: John Barrett = [mailto:jbarrett@carbinge.com]=
Sent: Friday, March 08, 2013 5:11 AM
To: lml@lancaironline.net
Subject: Pressurization
 
I didn=E2=80=99t think I=E2=80=99d need help with me= asurement issues, but I=E2=80=99m hitting some stone walls.
 
I have a pocket altimeter I thought I=E2=80=99d use = but wonder if it will have a stop on negative altitude.  Also I went o= nline to see how to convert altitude differential to PSID.  Not much l= uck.  The one site I found had conversion formulae that don=E2=80=99t = seem correct.  It lists a correlation 1=E2=80=9D of mercury to 1,000 f= eet of altitude and that should be ok.  It then goes on to list a .49 = conversion factor to get from inches of mercury to psi. 
 
My calculations show that at a service ceiling of FL= 290 the altitude difference to 10,000 foot cabin alt is 19,000 feet.  = .49 times this difference is about 9.5 PSID.  That=E2=80=99s WAY highe= r than the 5.0 PSI we=E2=80=99re supposed to be seeing in the LIVP at FL 29= 0.  I had hoped to test to about 6 PSI.
 
Short of an altimeter that allows negative readings = all the way to something over 19K and a formula that works, the only other = instrument I can think of is a gauge that reads psi.  I found some onl= ine that sell for from a couple hundred bucks to $450 or so.  They all= appeared to be set up for plumbing into a pipe system and I don=E2=80=99t = know if they would read correctly if placed inside the cockpit.
 
How have you IVP builders out there gone about getti= ng measurements when sealing up the pressure vessel?
 
Thanks,
 
John Barrett, CEO
Leading Edge Composites
PO Box 428
Port Hadlock, WA 98339
 
www.carbinge.com
 
 ----------MB_8CFEBB2DC697878_12D8_691BC_webmailstg-m01.sysops.aol.com--