X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Mon, 02 Jul 2012 21:35:43 -0400 Message-ID: X-Original-Return-Path: Received: from cdptpa-omtalb.mail.rr.com ([75.180.132.120] verified) by logan.com (CommuniGate Pro SMTP 5.4.6) with ESMTP id 5635456 for lml@lancaironline.net; Mon, 02 Jul 2012 17:09:39 -0400 Received-SPF: pass receiver=logan.com; client-ip=75.180.132.120; envelope-from=super_chipmunk@roadrunner.com X-Original-Return-Path: X-Authority-Analysis: v=2.0 cv=IuCcgcDg c=1 sm=0 a=+kuJ7Sa7hUpxs7xJxzDFzQ==:17 a=AeF9CLZUGkAA:10 a=zTVDa7HKqxcA:10 a=doupyKFmAAAA:8 a=Ia-xEzejAAAA:8 a=TxpdXIjkAAAA:8 a=8iMLa68cQLiVnYrHcMAA:9 a=pILNOxqGKmIA:10 a=EzXvWhQp4_cA:10 a=pGLkceISAAAA:8 a=Oq9Pw4I1Ncc-rNseNzAA:9 a=_W_S_7VecoQA:10 a=MSl-tDqOz04A:10 a=+kuJ7Sa7hUpxs7xJxzDFzQ==:117 X-Cloudmark-Score: 0 X-Originating-IP: 76.179.81.18 Received: from [76.179.81.18] ([76.179.81.18:49763] helo=WilliamHP) by cdptpa-oedge03.mail.rr.com (envelope-from ) (ecelerity 2.2.3.46 r()) with ESMTP id A1/53-17657-FED02FF4; Mon, 02 Jul 2012 21:09:03 +0000 X-Original-Message-ID: <375732A0B0A54F2EA424088571EEEFB3@WilliamHP> From: "Bill Wade" X-Original-To: "Lancair Mailing List" References: In-Reply-To: Subject: Re: [LML] Re: LN2 queries X-Original-Date: Mon, 2 Jul 2012 17:09:01 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_000F_01CD5875.60270400" X-Priority: 3 X-MSMail-Priority: Normal Importance: Normal X-Mailer: Microsoft Windows Live Mail 15.4.3555.308 X-MimeOLE: Produced By Microsoft MimeOLE V15.4.3555.308 This is a multi-part message in MIME format. ------=_NextPart_000_000F_01CD5875.60270400 Content-Type: text/plain; charset="Windows-1252" Content-Transfer-Encoding: quoted-printable One thing- if you had just filled one tank so that the nozzle that was = wet with fuel you might not want to ground the other tank cap with it. = Although it=92s not as convenient I think touching the cap with the = retractable ground wire is a good idea. The cap itself might not make a = good electrical connection to the filler neck though- I found the Newton = (Lancair) caps didn=92t make a good connection between the upper surface = and the lever. They=92re brand new- maybe they have a clear coat that = would wear off. Because my bonding harness is connected to the center = post I=92ll touch the lever before opening. I=92d suggest checking each cap with an ohmeter to see what the best = bonding path would be. -Bill Wade From: Paul Miller=20 Sent: Sunday, July 01, 2012 9:02 AM To: lml@lancaironline.net=20 Subject: [LML] Re: LN2 queries 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:=20 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: 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. 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. 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. 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. 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. 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 ------=_NextPart_000_000F_01CD5875.60270400 Content-Type: text/html; charset="Windows-1252" Content-Transfer-Encoding: quoted-printable
  One thing- if you had just filled one tank so that the = nozzle that=20 was wet with fuel you might not want to ground the other tank cap with = it.=20 Although it=92s not as convenient I think touching the cap with the = retractable=20 ground wire is a good idea. The cap itself might not make a good = electrical=20 connection to the filler neck though- I found the Newton (Lancair) caps = didn=92t=20 make a good connection between the upper surface and the lever. = They=92re brand=20 new- maybe they have a clear coat that would wear off. Because my = bonding=20 harness is connected to the center post I=92ll touch the lever before=20 opening.
 
I=92d suggest checking each cap with an ohmeter to see what the = best bonding=20 path would be.  -Bill Wade
 
Sent: Sunday, July 01, 2012 9:02 AM
Subject: [LML] Re: LN2 queries
 
If=20 you want a really good practical view of fuelling practices, bonding, = nozzle=20 etiquette and more, read this free manual--these guys probably have had = their=20 share of incidents:=20
 
http://forestry.ala= ska.gov/pdfs/2600fuel.pdf
 
Paul
Calgary
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=20 have seen electrical fuel senders with coils and wipers that are = directly=20 exposed to fuel.
 
  Sloshing around in a = fiberglass=20 tank, I believe the fuel could build a static charge on the surface. = Fuel=20 plumbing would normally be submerged so wouldn=92t help by wicking off = any=20 buildup. An isolated metal object such as the filler neck could = collect the=20 charge.
 
  Normally this wouldn=92t = be a problem=20 as the fuel tank is filled with such a high concentration of fuel = vapor that=20 it=92s too rich for combustion. I used to be a firefighter, eventually = fire=20 chief and this is what we were taught.
 
  During the filling process = 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=20 likely be inside the noncombustible zone and would remain that way = until=20 fueling was finished. Cars aren=92t grounded and yet they usually = don=92t catch=20 fire when being fueled. Even so, touching the cap with the ground wire = before=20 opening wouldn=92t hurt. Fuel nozzles are grounded so once a = connection was made=20 static should no longer be a problem.
 
  OTOH, I figure better safe = than=20 sorry. I thought about this quite a bit while building the Velocity = and the=20 picture shows my solution for the IV-P. Rather than try to ground the = entire=20 tank I made a cylinder of expanded copper mesh, sewed with copper wire = and=20 soldered. The lead formed is attached to the filler neck and also to = the cap,=20 using a braided ground strap to the adjusting nut. That connection = isn=92t=20 perfect but it also serves to keep the cap from falling off the wing. = The mesh=20 not only collects any charge but prevents trash from going into the = tank- I=92ve=20 heard of people sticking wrappers etc. into fuel tanks during = airshows. The=20 mesh was attached to the tank with Jeffco and slightly compressed when = the=20 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.=20 A 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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