X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Sun, 01 Jul 2012 09:02:31 -0400 Message-ID: X-Original-Return-Path: Received: from mail-pb0-f52.google.com ([209.85.160.52] verified) by logan.com (CommuniGate Pro SMTP 5.4.6) with ESMTPS id 5632120 for lml@lancaironline.net; Fri, 29 Jun 2012 16:13:50 -0400 Received-SPF: pass receiver=logan.com; client-ip=209.85.160.52; envelope-from=pjdmiller@gmail.com Received: by pbbro8 with SMTP id ro8so4978060pbb.25 for ; Fri, 29 Jun 2012 13:13:13 -0700 (PDT) Received: by 10.68.136.68 with SMTP id py4mr9045994pbb.151.1341000793699; Fri, 29 Jun 2012 13:13:13 -0700 (PDT) X-Original-Return-Path: Received: from [192.168.15.14] (S01060017ee00b6c0.cg.shawcable.net. [174.0.115.173]) by mx.google.com with ESMTPS id ku7sm6371418pbc.31.2012.06.29.13.13.12 (version=TLSv1/SSLv3 cipher=OTHER); Fri, 29 Jun 2012 13:13:13 -0700 (PDT) From: Paul Miller Mime-Version: 1.0 (Apple Message framework v1084) Content-Type: multipart/alternative; boundary=Apple-Mail-46--231158380 Subject: Re: [LML] Re: LN2 queries X-Original-Date: Fri, 29 Jun 2012 14:12:57 -0600 In-Reply-To: X-Original-To: "Lancair Mailing List" References: X-Original-Message-Id: <95B34738-FB5E-4642-9673-4E353CA2B516@gmail.com> X-Mailer: Apple Mail (2.1084) --Apple-Mail-46--231158380 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=windows-1252 If you want a really good practical view of fuelling practices, bonding, = nozzle etiquette and more, read this free manual--these guys probably = have had their share of incidents: http://forestry.alaska.gov/pdfs/2600fuel.pdf Paul Calgary On 2012-06-29, at 1:28 PM, Bill Wade wrote: > Second try with reduced image: > =20 > There are other possibilities- AVgas is nonconductive as far I = could tell by testing with a megohmeter. I have seen electrical fuel = senders with coils and wipers that are directly exposed to fuel. > =20 > Sloshing around in a fiberglass tank, I believe the fuel could build = a static charge on the surface. Fuel plumbing would normally be = submerged so wouldn=92t help by wicking off any buildup. An isolated = metal object such as the filler neck could collect the charge. > =20 > Normally this wouldn=92t be a problem as the fuel tank is filled = with such a high concentration of fuel vapor that it=92s too rich for = combustion. I used to be a firefighter, eventually fire chief and this = is what we were taught. > =20 > During the filling process concentrated fumes are displaced by fuel- = the danger zone is the interface between the concentrated fumes and the = outside air where the mixture becomes combustible. When the nozzle first = touches the filler neck it would most likely be inside the = noncombustible zone and would remain that way until fueling was = finished. Cars aren=92t grounded and yet they usually don=92t catch fire = when being fueled. Even so, touching the cap with the ground wire before = opening wouldn=92t hurt. Fuel nozzles are grounded so once a connection = was made static should no longer be a problem. > =20 > OTOH, I figure better safe than sorry. I thought about this quite a = bit while building the Velocity and the picture shows my solution for = the IV-P. Rather than try to ground the entire tank I made a cylinder of = expanded copper mesh, sewed with copper wire and soldered. The lead = formed is attached to the filler neck and also to the cap, using a = braided ground strap to the adjusting nut. That connection isn=92t = perfect but it also serves to keep the cap from falling off the wing. = The mesh not only collects any charge but prevents trash from going into = the tank- I=92ve heard of people sticking wrappers etc. into fuel tanks = during airshows. The mesh was attached to the tank with Jeffco and = slightly compressed when the tank was closed up. > =20 > In use, the procedure would be to touch the ground wire to the cap = before opening, and I=92ll placard the filler. A ground wire could also = be connected to the cap lead once it was open. In addition, I think Pete = Cavitt=92s method to remove surface static makes a lot of sense. -Bill = Wade --Apple-Mail-46--231158380 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=windows-1252 If = you want a really good practical view of fuelling practices, bonding, = nozzle etiquette and more, read this free manual--these guys probably = have had their share of incidents:


Paul
Calga= ry
On 2012-06-29, at 1:28 PM, Bill Wade wrote:

  Second try with reduced image:
 
   There are other = possibilities-=20 AVgas is nonconductive as far I could tell by testing with a megohmeter. = I have=20 seen electrical fuel senders with coils and wipers that are directly = exposed to=20 fuel.
 
  Sloshing around in a = fiberglass tank,=20 I believe the fuel could build a static charge on the surface. Fuel = plumbing=20 would normally be submerged so wouldn=92t help by wicking off any = buildup. An=20 isolated metal object such as the filler neck could collect the = charge.
 
  Normally this wouldn=92t be = a problem as=20 the fuel tank is filled with such a high concentration of fuel vapor = that it=92s=20 too rich for combustion. I used to be a firefighter, eventually fire = chief and=20 this is what we were taught.
 
  During the filling process=20= concentrated fumes are displaced by fuel- the danger zone is the = interface=20 between the concentrated fumes and the outside air where the mixture = becomes=20 combustible. When the nozzle first touches the filler neck it would most = likely=20 be inside the noncombustible zone and would remain that way until = fueling was=20 finished. Cars aren=92t grounded and yet they usually don=92t catch fire = when being=20 fueled. Even so, touching the cap with the ground wire before opening = wouldn=92t=20 hurt. Fuel nozzles are grounded so once a connection was made static = should no=20 longer be a problem.
 
  OTOH, I figure better safe = than sorry.=20 I thought about this quite a bit while building the Velocity and the = picture=20 shows my solution for the IV-P. Rather than try to ground the entire = tank I made=20 a cylinder of expanded copper mesh, sewed with copper wire and soldered. = The=20 lead formed is attached to the filler neck and also to the cap, using a = braided=20 ground strap to the adjusting nut. That connection isn=92t perfect but = it also=20 serves to keep the cap from falling off the wing. The mesh not only = collects any=20 charge but prevents trash from going into the tank- I=92ve heard of = people=20 sticking wrappers etc. into fuel tanks during airshows. The mesh was = attached to=20 the tank with Jeffco and slightly compressed when the tank was closed = up.
 
  In use, the procedure would = be to=20 touch the ground wire to the cap before opening, and I=92ll placard the = filler. A=20 ground wire could also be connected to the cap lead once it was open. In=20= addition, I think Pete Cavitt=92s method to remove surface static makes = a lot of=20 sense.  -Bill Wade

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