X-Virus-Scanned: clean according to Sophos on Logan.com From: "Charlie England" Received: from mail-it0-f43.google.com ([209.85.214.43] verified) by logan.com (CommuniGate Pro SMTP 6.2c1) with ESMTPS id 9579810 for flyrotary@lancaironline.net; Fri, 17 Mar 2017 11:38:51 -0400 Received-SPF: pass receiver=logan.com; client-ip=209.85.214.43; envelope-from=ceengland7@gmail.com Received: by mail-it0-f43.google.com with SMTP id m27so26575760iti.0 for ; Fri, 17 Mar 2017 08:38:50 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:references:from:message-id:date:user-agent:mime-version :in-reply-to; bh=3oLL7mfyqzllVaImDnDIyhdxC9FsUxgJMK1s3kIVA5w=; b=eCqNqInH53xhbPW97tF32WVv41noq518Rd/MN/FmYUS3Jxnru82e/htVrUsmcXPkrR /nCUDVn3XVtahOZSjw60toKWkgju8KU8iZvIXVlH1hGa43U1tlXYyryAXhqF56jY92ys ErlgQswZFXQuAnsZ6OhKv8RAYh6NbM+sAbs7H1d5tFVDpvLPhzed9VL9ip0DgubjIoEl phXOvMgUX0Syxwyw1RzarvCuB4kBGJ2J2wTxlYGZTmz3TrF3K13mzJDCJJc0CX2weorR SBkCF6rX4j9quhxBDvIUbaqeUY65sPIjpK/RugyCf222s2SkyX+cLStoAN5L185syEG9 yJRQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:references:from:message-id:date :user-agent:mime-version:in-reply-to; bh=3oLL7mfyqzllVaImDnDIyhdxC9FsUxgJMK1s3kIVA5w=; b=R2zOP3trVM+t85YetiaqibMVGYQlq82U7QBREqUQmhikF3yQeaHy9hv09DFCaYuWQg PmNqF5vGkfxljmIFLjDpslMCaxjMfsrXrKYIXtE6E/niX9duYa7dZiiaocsoxhCy4yvp 77YC7gB7IzqiB9CXFZpckFMXleMYeP2kK1OJNMd3E9sFOt6rdSuqQpujxx6YolWi0DVl NyYUhtQd+Xf9GfmY/J59GSHw0xr5wy2P/d0irXVO8VqopNCrHDnK/yK1z0r1poSEjXdh 5nN9OK+5xNbTdVI4j17LDMRv4hau5Nj9L0t7dCETNlf8MSVBnODVjJg+6sEVjVtrQLfC QCeg== X-Gm-Message-State: AFeK/H0wlbmQVFg+3QgP77v1tGVnizM7CtepJR1WrS1kvuFvl5Q8OIcbAaNl6lUvJhxgaw== X-Received: by 10.107.132.155 with SMTP id o27mr14983346ioi.138.1489765030983; Fri, 17 Mar 2017 08:37:10 -0700 (PDT) Return-Path: Received: from ?IPv6:2602:306:25fb:1599:354d:d8c4:7dac:5904? ([2602:306:25fb:1599:354d:d8c4:7dac:5904]) by smtp.googlemail.com with ESMTPSA id n10sm1192187itg.8.2017.03.17.08.37.09 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 17 Mar 2017 08:37:10 -0700 (PDT) Subject: Re: [FlyRotary] Re: Fuel Pump and Regulator To: Rotary motors in aircraft References: Message-ID: <6fb49c00-1e68-b0a4-6a87-95c7e36eebb3@gmail.com> Date: Fri, 17 Mar 2017 10:39:00 -0500 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.8.0 MIME-Version: 1.0 In-Reply-To: Content-Type: multipart/alternative; boundary="------------00E54DB2C8C43F2B32F388B9" This is a multi-part message in MIME format. --------------00E54DB2C8C43F2B32F388B9 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 8bit I don't think you need to change your breakers. If you re-read my post, I think you'll see that you're fine with what you have. CB's are (typically) designed so that you size them at around 10-20% above normal continuous load, and their designed-in protection delay curve allows for surges. Fast blow fuses, on the other hand, must be sized so that the maximum surge load is well below the rating on the fuse. That's almost certainly why your 10A CB's work fine, but his 10A fuses are blowing. The Walbro seems to run at between 6 & 10 amps, but can surge to (I'm guessing now) probably around 15 amps in some circumstances. Hence, the 20A (fast-blow) fuse requirement. BTW, contrary to popular belief, the fuse or breaker is there to protect the wire, not the device. If you upsize to a 20A CB, can your wire handle 40 amps for up to 20 seconds without melting the insulation? Charlie On 3/17/2017 9:29 AM, Jeff Whaley wrote: > > Thanks Charlie, yes checked the Spruce website myself and can see the > 20 Amp marking on their pump image. Will visually check my pumps - > if they are stamped “20 Amps”, I’ll order two of the Tyco parts in 20 > Amp. I have been fine so far but double-fine is better. > > Jeff > > Image of the Walbro attached. Around the curve is the word 'required'. > > If you download the data sheet (available on the Spruce product page), > it'll show that a 200% load (20 amps, in this case) takes anywhere > from 6 to 22 seconds to trip the breaker. So you're fine. In contrast, > Littlefuse brand ATC blade fuses are rated to blow in 0.75 to 1.8 > seconds at a 135% (13.5 amps) load. > > --------------00E54DB2C8C43F2B32F388B9 Content-Type: text/html; charset=windows-1252 Content-Transfer-Encoding: 8bit
I don't think you need to change your breakers. If you re-read my post, I think you'll see that you're fine with what you have. CB's are (typically) designed so that you size them at around 10-20% above normal continuous load, and their designed-in protection delay curve allows for surges. Fast blow fuses, on the other hand, must be sized so that the maximum surge load is well below the rating on the fuse. That's almost certainly why your 10A CB's work fine, but his 10A fuses are blowing. The Walbro seems to run at between 6 & 10 amps, but can surge to (I'm guessing now) probably around 15 amps in some circumstances. Hence, the 20A (fast-blow) fuse requirement.

BTW, contrary to popular belief, the fuse or breaker is there to protect the wire, not the device. If you upsize to a 20A CB, can your wire handle 40 amps for up to 20 seconds without melting the insulation?

Charlie

On 3/17/2017 9:29 AM, Jeff Whaley wrote:

Thanks Charlie, yes checked the Spruce website myself and can see the 20 Amp marking on their pump image.  Will visually check my pumps  -   if they are stamped “20 Amps”,  I’ll order two of the Tyco parts in 20 Amp.  I have been fine so far but double-fine is better.

Jeff

 

Image of the Walbro attached. Around the curve is the word 'required'. 

 

If you download the data sheet (available on the Spruce product page), it'll show that a 200% load (20 amps, in this case) takes anywhere from 6 to 22 seconds to trip the breaker. So you're fine. In contrast, Littlefuse brand ATC blade fuses are rated to blow in 0.75 to 1.8 seconds at a 135% (13.5 amps) load.

 


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