X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: <marv@lancaironline.net> Sender: <marv@lancaironline.net> To: lml@lancaironline.net Date: Sun, 10 Mar 2013 10:11:51 -0400 Message-ID: <redirect-6114233@logan.com> X-Original-Return-Path: <pete@leapfrogventures.com> Received: from p3plex2out04.prod.phx3.secureserver.net ([184.168.131.18] verified) by logan.com (CommuniGate Pro SMTP 6.0.2) with ESMTP id 6113452 for lml@lancaironline.net; Sat, 09 Mar 2013 12:20:12 -0500 Received-SPF: none receiver=logan.com; client-ip=184.168.131.18; envelope-from=pete@leapfrogventures.com Received: from P3PW5EX1HT003.EX1.SECURESERVER.NET ([72.167.180.21]) by p3plex2out04.prod.phx3.secureserver.net with secureserver.net id 9VKc1l0010U5vnL01VKc8S; Sat, 09 Mar 2013 10:19:36 -0700 Received: from P3PW5EX1MB14.EX1.SECURESERVER.NET ([10.6.135.86]) by P3PW5EX1HT003.EX1.SECURESERVER.NET ([72.167.180.21]) with mapi; Sat, 9 Mar 2013 10:19:36 -0700 From: "pete@leapfrogventures.com" <pete@leapfrogventures.com> X-Original-To: John Barrett <jbarrett@carbinge.com>, "lml@lancaironline.net" <lml@lancaironline.net> X-Original-Date: Sat, 9 Mar 2013 10:18:48 -0700 Subject: RE: Pressurization Thread-Topic: Pressurization Thread-Index: Ac4ctUaKljOvlisGRTmosjKiZ5BsUgAM4BGQ X-Original-Message-ID: <2A14E6258A8534418F5498D73CCA51EF2243E99368@P3PW5EX1MB14.EX1.SECURESERVER.NET> References: <redirect-6111379@logan.com> In-Reply-To: <redirect-6111379@logan.com> 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_2A14E6258A8534418F5498D73CCA51EF2243E99368P3PW5EX1MB14E_" MIME-Version: 1.0 --_000_2A14E6258A8534418F5498D73CCA51EF2243E99368P3PW5EX1MB14E_ Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable John, 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. 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. 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). 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. Pete From: John Barrett [mailto:jbarrett@carbinge.com] Sent: Friday, March 08, 2013 5:11 AM To: lml@lancaironline.net Subject: Pressurization I didn't think I'd need help with measurement issues, but I'm hitting some = stone walls. I have a pocket altimeter I thought I'd use but wonder if it will have a st= op 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 conversion= formulae that don't seem correct. It lists a correlation 1" 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. 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's WAY higher than the 5.0 PSI we're supposed to be s= eeing in the LIVP at FL 290. I had hoped to test to about 6 PSI. 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't know if they would read correctly if plac= ed inside the cockpit. How have you IVP builders out there gone about getting measurements when se= aling up the pressure vessel? Thanks, John Barrett, CEO Leading Edge Composites PO Box 428 Port Hadlock, WA 98339 www.carbinge.com<http://www.carbinge.com> --_000_2A14E6258A8534418F5498D73CCA51EF2243E99368P3PW5EX1MB14E_ Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable <html xmlns:v=3D"urn:schemas-microsoft-com:vml" xmlns:o=3D"urn:schemas-micr= osoft-com:office:office" xmlns:w=3D"urn:schemas-microsoft-com:office:word" = xmlns:m=3D"http://schemas.microsoft.com/office/2004/12/omml" xmlns=3D"http:= //www.w3.org/TR/REC-html40"><head><meta http-equiv=3DContent-Type content= =3D"text/html; charset=3Dus-ascii"><meta name=3DGenerator content=3D"Micros= oft Word 14 (filtered medium)"><style><!-- /* Font Definitions */ @font-face {font-family:Calibri; panose-1:2 15 5 2 2 2 4 3 2 4;} @font-face {font-family:Tahoma; panose-1:2 11 6 4 3 5 4 4 2 4;} /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {margin:0in; margin-bottom:.0001pt; font-size:11.0pt; font-family:"Calibri","sans-serif";} a:link, span.MsoHyperlink {mso-style-priority:99; color:blue; text-decoration:underline;} a:visited, span.MsoHyperlinkFollowed {mso-style-priority:99; color:purple; text-decoration:underline;} span.EmailStyle17 {mso-style-type:personal; font-family:"Calibri","sans-serif"; color:windowtext;} span.EmailStyle18 {mso-style-type:personal-reply; font-family:"Calibri","sans-serif"; color:#1F497D; font-weight:normal; font-style:normal;} .MsoChpDefault {mso-style-type:export-only; font-size:10.0pt;} @page WordSection1 {size:8.5in 11.0in; margin:1.0in 1.0in 1.0in 1.0in;} div.WordSection1 {page:WordSection1;} --></style><!--[if gte mso 9]><xml> <o:shapedefaults v:ext=3D"edit" spidmax=3D"1026" /> </xml><![endif]--><!--[if gte mso 9]><xml> <o:shapelayout v:ext=3D"edit"> <o:idmap v:ext=3D"edit" data=3D"1" /> </o:shapelayout></xml><![endif]--></head><body lang=3DEN-US link=3Dblue vli= nk=3Dpurple><div class=3DWordSection1><p class=3DMsoNormal><span style=3D'c= olor:#1F497D'>John,<o:p></o:p></span></p><p class=3DMsoNormal><span style= =3D'color:#1F497D'><o:p> </o:p></span></p><p class=3DMsoNormal><span s= tyle=3D'color:#1F497D'>I assume you are adding a cabin altimeter to your in= strument panel? It reads out both the cabin differential in psi and t= he cabin altitude. It is a must have IMHO to monitor and prevent cabi= n over-pressurization. It is the only test instrument needed for cali= brating the Dukes and sealing the cabin.<o:p></o:p></span></p><p class=3DMs= oNormal><span style=3D'color:#1F497D'><o:p> </o:p></span></p><p class= =3DMsoNormal><span style=3D'color:#1F497D'>I know that there is an overpres= sure valve that mounts next to the Dukes. However, my Dukes head was = not working properly during testing and was not opening. The overpres= sure valve was no match for the amount of pressurized air coming in the cab= in, and the pressure quickly went over 6.5 psi before I was able to do a ma= nual dump. If you look at the teeny size of the overpressure valve an= d compare that to the volume of pressurized air coming into the cabin on cl= imb-out, you will quickly come to the conclusion that it provides inadequat= e over pressurization protection.<o:p></o:p></span></p><p class=3DMsoNormal= ><span style=3D'color:#1F497D'><o:p> </o:p></span></p><p class=3DMsoNo= rmal><span style=3D'color:#1F497D'>I think you are using a G900 like me.&nb= sp; It has an annunciator input called CABIN ALTITUDE. I connected th= at 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 (w= here the switch is mounted). In case the Dukes valve fails and the ca= bin pressure rises too high, at least I will get some notice (see note abov= e about not depending on the manual vent valve).<o:p></o:p></span></p><p cl= ass=3DMsoNormal><span style=3D'color:#1F497D'><o:p> </o:p></span></p><= p class=3DMsoNormal><span style=3D'color:#1F497D'>I do have a digital diffe= rential manometer that measures PSI you are welcome to borrow. I used= it to calibrate the overpressure valve that mounts next to the Dukes (I se= t it to 6psi). I built a plenum from a large plastic food container t= hat you can pressurize with a compressor (carefully) that you can borrow as= well.<o:p></o:p></span></p><p class=3DMsoNormal><span style=3D'color:#1F49= 7D'><o:p> </o:p></span></p><div><p class=3DMsoNormal><span style=3D'co= lor:#1F497D'>Pete<o:p></o:p></span></p></div><p class=3DMsoNormal><span sty= le=3D'color:#1F497D'><o:p> </o:p></span></p><div><div style=3D'border:= none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'><p class=3DM= soNormal><b><span style=3D'font-size:10.0pt;font-family:"Tahoma","sans-seri= f"'>From:</span></b><span style=3D'font-size:10.0pt;font-family:"Tahoma","s= ans-serif"'> John Barrett [mailto:jbarrett@carbinge.com] <br><b>Sent:</b> F= riday, March 08, 2013 5:11 AM<br><b>To:</b> lml@lancaironline.net<br><b>Sub= ject:</b> Pressurization<o:p></o:p></span></p></div></div><p class=3DMsoNor= mal><o:p> </o:p></p><p class=3DMsoNormal>I didn’t think I’= d need help with measurement issues, but I’m hitting some stone walls= .<o:p></o:p></p><p class=3DMsoNormal><o:p> </o:p></p><p class=3DMsoNor= mal>I have a pocket altimeter I thought I’d use but wonder if it will= have a stop on negative altitude. Also I went online to see how to c= onvert altitude differential to PSID. Not much luck. The one si= te I found had conversion formulae that don’t seem correct. It = lists a correlation 1” 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. <o:p></o:p></p><p class=3DMsoNormal><o= :p> </o:p></p><p class=3DMsoNormal>My calculations show that at a serv= ice ceiling of FL290 the altitude difference to 10,000 foot cabin alt is 19= ,000 feet. .49 times this difference is about 9.5 PSID. That= 217;s WAY higher than the 5.0 PSI we’re supposed to be seeing in the = LIVP at FL 290. I had hoped to test to about 6 PSI.<o:p></o:p></p><p = class=3DMsoNormal><o:p> </o:p></p><p class=3DMsoNormal>Short of an alt= imeter 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 t= hat reads psi. I found some online that sell for from a couple hundre= d bucks to $450 or so. They all appeared to be set up for plumbing in= to a pipe system and I don’t know if they would read correctly if pla= ced inside the cockpit. <o:p></o:p></p><p class=3DMsoNormal><o:p> </o:= p></p><p class=3DMsoNormal>How have you IVP builders out there gone about g= etting measurements when sealing up the pressure vessel?<o:p></o:p></p><p c= lass=3DMsoNormal><o:p> </o:p></p><p class=3DMsoNormal>Thanks,<o:p></o:= p></p><p class=3DMsoNormal><o:p> </o:p></p><p class=3DMsoNormal>John B= arrett, CEO<o:p></o:p></p><p class=3DMsoNormal>Leading Edge Composites<o:p>= </o:p></p><p class=3DMsoNormal>PO Box 428<o:p></o:p></p><p class=3DMsoNorma= l>Port Hadlock, WA 98339<o:p></o:p></p><p class=3DMsoNormal><o:p> </o:= p></p><p class=3DMsoNormal><a href=3D"http://www.carbinge.com">www.carbinge= .com</a><o:p></o:p></p><p class=3DMsoNormal><o:p> </o:p></p></div></bo= dy></html>= --_000_2A14E6258A8534418F5498D73CCA51EF2243E99368P3PW5EX1MB14E_--