X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Sat, 04 Jun 2011 09:52:02 -0400 Message-ID: X-Original-Return-Path: Received: from elasmtp-galgo.atl.sa.earthlink.net ([209.86.89.61] verified) by logan.com (CommuniGate Pro SMTP 5.4c3j) with ESMTP id 5002522 for lml@lancaironline.net; Fri, 03 Jun 2011 09:45:33 -0400 Received-SPF: none receiver=logan.com; client-ip=209.86.89.61; envelope-from=Colyncase@earthlink.net DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=dk20050327; d=earthlink.net; b=oAmX3S7Le3MOpTKZj+o0vqNAwIm5i4Gef1qu4Q8J1OrSzdYwDJ+kC3vCJta/fSHm; h=Received:From:Content-Type:Subject:Date:Message-Id:To:Mime-Version:X-Mailer:X-ELNK-Trace:X-Originating-IP; Received: from [216.57.118.194] (helo=[192.168.1.100]) by elasmtp-galgo.atl.sa.earthlink.net with esmtpa (Exim 4.67) (envelope-from ) id 1QSUgM-0001k9-8i for lml@lancaironline.net; Fri, 03 Jun 2011 09:44:58 -0400 From: Colyn Case Content-Type: multipart/alternative; boundary=Apple-Mail-310-236499756 Subject: fuel vent check valve design issue? X-Original-Date: Fri, 3 Jun 2011 09:44:57 -0400 X-Original-Message-Id: <2F2D47BC-8235-4328-9FC0-061D4196E7C6@earthlink.net> X-Original-To: "lml@lancaironline.net List" Mime-Version: 1.0 (Apple Message framework v1082) X-Mailer: Apple Mail (2.1082) X-ELNK-Trace: 63d5d3452847f8b1d6dd28457998182d7e972de0d01da9407bc3baa5307cc3ff750fc1df30db8f70350badd9bab72f9c350badd9bab72f9c350badd9bab72f9c X-Originating-IP: 216.57.118.194 --Apple-Mail-310-236499756 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=us-ascii So all the discussion about fuel vents and check valves got me thinking. I did a crude experiment with my Andair bleed-option (CK250E-B) check = valves and found that the wrong-way flow is about 1 gallon/minute at = (whatever I can manage with my lungs) about 1 psi. So the first question is how much gas will they flow in the wrong = direction if they flow 1 gallon/minute of air. ? The second question I posed was this: Suppose you have only 10 gallons = in one tank and you take off and climb to fl200 in x minutes. Up there = the pressure is half what it is on the ground so you will have to vent = 40 gallons. So if x is less than 40 you are going to have a positive = pressure in the tank when you arrive at fl200. In my plane, x could be = as low as 10, leaving multiple psi in the tank. This doesn't seem = healthy. So question for anyone who has these valves installed: 1) if you've = ever done something like my proposed scenario, did you observe the wings = bulging? 2) are you convinced there is any benefit to the valves so = far as reducing fuel going overboard on the ground? I did disassemble the valves and determined that I could modify the = outflow rate by drilling out the two little holes in the shuttle. = However, this would further diminish the benefit as far as retaining = fuel. Overall, my conclusion is that the valves as shipped have inadequate = outflow rate which will create excess pressure in the wing if you climb = with partially filled tanks. Colyn --Apple-Mail-310-236499756 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=us-ascii So = all the discussion about fuel vents and check valves got me = thinking.

I did a crude experiment with my Andair = bleed-option (CK250E-B) check valves and found that the wrong-way flow = is about 1 gallon/minute at (whatever I can manage with my lungs) about = 1 psi.

So the first question is how much = gas will they flow in the wrong direction if they flow 1 = gallon/minute of air. ?

The = second question I posed was this: Suppose you have only 10 = gallons in one tank and you take off and climb to fl200 in x minutes. = Up there the pressure is half what it is on the ground so you = will have to vent 40 gallons. So if x is less than 40 you are = going to have a positive pressure in the tank when you arrive at fl200. = In my plane, x could be as low as 10, leaving multiple psi in the = tank. This doesn't seem healthy.

So = question for anyone who has these valves installed: = 1) if you've ever done something like my proposed scenario, did you = observe the wings bulging? 2) are you convinced there is any = benefit to the valves so far as reducing fuel going overboard on the = ground?

I did disassemble the valves and = determined that I could modify the outflow rate by drilling out the two = little holes in the shuttle. However, this would further diminish = the benefit as far as retaining fuel.

Overall, = my conclusion is that the valves as shipped have inadequate outflow rate = which will create excess pressure in the wing if you climb with = partially filled = tanks.

Colyn

<= /body>= --Apple-Mail-310-236499756--