Received-SPF: none
 receiver=logan.com; client-ip=140.172.240.5; envelope-from=william.p.dube@noaa.gov
Message-ID: <44593DFE.8010400@noaa.gov>
Date: Wed, 03 May 2006 17:34:22 -0600
From: Bill Dube <william.p.dube@noaa.gov>
Reply-To:  william.p.dube@noaa.gov
Organization: NOAA Aeronomy Lab
User-Agent: Mozilla Thunderbird 1.0.2 (Windows/20050317)
MIME-Version: 1.0
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: Annulus instead of oriface (was: Fuel system pressure bleed off)
References: <list-1090796@logan.com>
In-Reply-To: <list-1090796@logan.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit

I have found that a better alternative to a simple orifice (in most 
applications) is a larger hole with a section of piano wire in the 
middle of it. The annulus formed is much less prone to clogging than a 
single hole. You put the piano wire through and then bend a sharp 90 in 
both ends to keep it in place. This is the way they construct the 
damping orifice on high-end laboratory pressure gages.

    Bill Dube'

Ben Schneider wrote:

> Group...
>    I am installing my fuel system on my Renesis right now. I seem to 
> remember (correct me if I am wrong)  that the consensus was to use a 
> .020 orfice bypass of the regulator to bleed off the pressure in the 
> event of pump prime loss.
> My question is, how exactly are some of you going about this? Are you 
> welding an AN fitting shut, then drilling it out to .020? Is there 
> something of this nature commercially available?  Suggestions?  I have 
> only to run the fuel lines, then wire the engine, a few other little 
> misc. items, and I should be ready for first engine start.
>
> Ben Schneider   N713R   RV7 Renesis