Date:         Thu, 20 Apr 2000 13:16:41 -0400
Reply-To:     David Beierl <dbeierl@IBM.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         David Beierl <dbeierl@IBM.NET>
Subject:      Re: Physics of LP tank filling Was: Filling LP tank for the first
              time
Comments: To: Sean Garrett <seangar@HOTMAIL.COM>
In-Reply-To:  <20000420153815.25398.qmail@hotmail.com>
Content-Type: text/plain; charset="us-ascii"; format=flowed

At 11:38 4/20/2000, Sean Garrett wrote:
>I got to thinking about the physics of this last night and I may be wrong.
>LP is Liquified Petroleum, right? A liquid does not compress, right? It is a
>liquid because it is compressed. Therefore it might not matter about the
>size of the holes for bleeding and filling. A liquid will exit as slow/fast
>as it enters the tank no matter the size of the holes. The problem with this

This would be true if the tank were completely full of liquid -- since it
isn't, the incoming flow compresses the headspace until the pressure in the
tank equals the pump pressure.  After that the flows equalize, unless the
restriction causes the fill pump to increase its pressure.  I suspect (but
don't know) that they use a centrifugal, i.e. non-positive-displacement
pump at fairly low pressure; I've seen Acme fill valves rated at GPM with
10 psi differential pressure.

david
David Beierl - Providence, RI
  http://pws.prserv.net/synergy/Vanagon/
'84 Westy "Dutiful Passage"
'85 GL "Poor Relation"