X-Virus-Scanned: clean according to Sophos on Logan.com From: "Mark Steitle" Received: from mail-ig0-f177.google.com ([209.85.213.177] verified) by logan.com (CommuniGate Pro SMTP 6.0.10) with ESMTPS id 7242887 for flyrotary@lancaironline.net; Wed, 29 Oct 2014 13:30:55 -0400 Received-SPF: pass receiver=logan.com; client-ip=209.85.213.177; envelope-from=msteitle@gmail.com Received: by mail-ig0-f177.google.com with SMTP id hl2so2612605igb.4 for ; Wed, 29 Oct 2014 10:30:19 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; bh=ytKJ/kdMUH+bc0Uu6o008OBtA+3k2EXhq6AY2m5u3/U=; b=w1fbQnkI+NIkgiWOJXKlaQT7AVATT5gyN0S/W9yjfBHikq2ZjljxQITsz9ZCqC8yiN FWXTjUOe7147ZDJhlZbC3aCuK7e//9sa6PTBLio1AvIHgsUs3QDNChvVa8ArYoy4HH2+ DCyP9fNqoDUHCSYyJNPmvRkxq31NNsFesayalBsbKWw2I2ksKn1iGq4tipTaf74uF5GG agIS47RGNcjKOHD6KG/jk/DxKrhp4jXeuRSCTBcFm7Fl784GmpYwDIxRd6WNeBHqSfbA V6oZX5SfyjFEQOKJnA2X3LILFDzie9A8ul09qXfVrP1aYMyIrJkpJVwfF+ZgwVBXoxvX UdUw== MIME-Version: 1.0 X-Received: by 10.42.227.130 with SMTP id ja2mr11977441icb.16.1414603819416; Wed, 29 Oct 2014 10:30:19 -0700 (PDT) Received: by 10.107.152.195 with HTTP; Wed, 29 Oct 2014 10:30:19 -0700 (PDT) In-Reply-To: References: Date: Wed, 29 Oct 2014 12:30:19 -0500 Message-ID: Subject: Re: [FlyRotary] Re: electric fuel selector valves To: Rotary motors in aircraft Content-Type: multipart/alternative; boundary=001a1133d7502782300506931e26 --001a1133d7502782300506931e26 Content-Type: text/plain; charset=ISO-8859-1 Ernest, The latest plastic part failure that comes to mind is the plastic overflow tank on my 2007 Mazda 3. It is under something like 18-20 psi. It developed stress cracks near a seam. I also have seen failures in plastic radiator end tanks. Of course, this could be the fault of a ham-handed mechanic, or not. Then again, I have also seen brass radiator tanks with cracks. You made a good point about AN fittings. Hoses need to be supported in some fashion other than hanging by the fitting. Mark On Wed, Oct 29, 2014 at 8:32 AM, Ernest Christley < flyrotary@lancaironline.net> wrote: > > > > On Tuesday, October 28, 2014 9:26 PM, Mark Steitle < > flyrotary@lancaironline.net> wrote: > > > >Six PSI is one thing, 40 psi is much different. I've experienced too > many cracked plastic parts on cars, trucks and > >RV's to feel comfortable putting me and my family inside a cabin with a > plastic RV fuel valve. A small crack under > >40 psi can cause a very real fire hazard. To me, this is a no-brainer. > > I have to give you that. I'm not sure I would want to put a plastic valve > under pressure and expect it to operate reliably either. 40psi really > isn't all THAT much, but I'd still want to design the system so that > plastic parts came before the pumps. > > Did the cracks you experienced have a common theme (barbs breaking off? > body of the valve cracking open? mostly located in the engine compartment > where heat would prematurely age them?) I ask so that I can avoid a hidden > snake, if at all possible. > > >If its the cost of a quality aircraft quality valve, then get a part time > job and save up your lunch money. That's my reasoning. > > Cost is one thing. > Defining "quality" is another. That goes back to replacing the 1000lb > rope with a 100,000lb chain. The rope is sufficient, but the chain is > "better", because it is stronger, even though it causes a host of its own > problems. It is heavy. It doesn't roll smoothly through a pulley. It > will rust. In my case, the only fuel leak problems I've had were at the > AN's metal to metal fittings. > What really grates though is design mismatches. Everyone is using stiff, > steel braided hoses to connect a stationary firewall to a vibrating carb, > the vibrational stress being absorbed by an aluminum fitting. We go to > extreme lengths to avoid NPT fittings on the ends of tubes and hoses, > mainly by screwing NPT-AN adapters into all the NPT holes. We use steel > braided hose to protect against "abrasion", when everyone knows a properly > laid out system should not have hoses rubbing (and what is done to protect > what it was abrading against?). We use steel braided hose to protect the > hose from fire, as if a porous metal screen will somehow slow the heat > down. Now Steve relates that his father was convinced by a racing guy that > a steel braid will somehow protect the rubber inside from ethanol > incompatibility. At some point the lack of logic assaults the senses and > you just have to stop and say, "WTF, guys?! What were we building again?" > > >Oh, one more thing... my kit included a 6-way Andair valve. So, the > decision was easy. > > hehe. Yeah, that does make a difference 8*) > --001a1133d7502782300506931e26 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable
Ernest,
=A0
The latest plastic p= art failure that comes to mind is the plastic overflow tank on my 2007=A0Ma= zda 3.=A0 It is under something like 18-20 psi.=A0 It developed stress crac= ks near a seam.=A0
=A0
I also have seen failures in pl= astic radiator end tanks.=A0 Of course, this could be the fault of a ham-ha= nded mechanic, or not.=A0 Then again, I have also seen brass radiator tanks= with cracks.=A0 =A0
=A0
You made a good point about A= N fittings.=A0 Hoses need to be supported=A0in some fashion=A0other than ha= nging=A0by the fitting.
=A0
Mark=A0

On Wed, Oct 29, 2014 at = 8:32 AM, Ernest Christley <flyrotary@lancaironline.net> wrote:



On Tuesday, October 28, 2014 9:26 PM, Mar= k Steitle <flyrotary@lancaironline.net> wrote:


=
>Six PSI is one thing, 40 psi is much d= ifferent.=A0 I've experienced too many cracked plastic parts on cars, t= rucks and
>RV's to feel comfortable putting me and my family insi= de a cabin with a plastic RV fuel valve.=A0 A small crack under
>40 psi can cause a ve= ry real fire hazard.=A0 To me, this is a no-brainer.=A0

I have to g= ive you that.=A0 I'm not sure I would want to put a plastic valve under= pressure and expect it to operate reliably either.=A0 40psi really isn'= ;t all THAT much, but I'd still want to design the system so that plast= ic parts came before the pumps.

Did the cracks you experienced have = a common theme (barbs breaking off?=A0 body of the valve cracking open? mos= tly located in the engine compartment where heat would prematurely age them= ?)=A0 I ask so that I can avoid a hidden snake, if at all possible.=A0
=
>If its the cost of a quality aircraft quality valve, then get a par= t time job and save up your lunch money.=A0 That's my reasoning.=A0
Cost is one thing.
Defining "quality" is another.=A0 Tha= t goes back to replacing the 1000lb rope with a 100,000lb chain.=A0 The rope is sufficient, but the chain is "better", bec= ause it is stronger, even though it causes a host of its own problems.=A0 I= t is heavy.=A0 It doesn't roll smoothly through a pulley.=A0 It will ru= st.=A0 In my case, the only fuel leak problems I've had were at the AN&= #39;s metal to metal fittings.=A0
What really grates though is design m= ismatches.=A0 Everyone is using stiff, steel braided hoses to connect a sta= tionary firewall to a vibrating carb, the vibrational stress being absorbed= by an aluminum fitting.=A0 We go to extreme lengths to avoid NPT fittings = on the ends of tubes and hoses, mainly by screwing NPT-AN adapters into all= the NPT holes.=A0 We use steel braided hose to protect against "abras= ion", when everyone knows a properly laid out system should not have h= oses rubbing (and what is done to protect what it was abrading against?).= =A0 We use steel braided hose to protect the hose from fire, as if a porous metal screen will somehow slow the heat down.=A0 Now Steve relates = that his father was convinced by a racing guy that a steel braid will someh= ow protect the rubber inside from ethanol incompatibility.=A0 At some point= the lack of logic assaults the senses and you just have to stop and say, &= quot;WTF, guys?!=A0 What were we building again?"

>Oh,= one more thing... my kit included a 6-way Andair valve.=A0 So, the decisio= n was easy.

hehe.=A0 Yeah, that does make a difference= =A0 8*)
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