REFLECTOR: FUEL FEED & Vents--blinking warning

[KeithHallsten]

If we assume that the float is truly sealed and reasonably rigid, then its
mass will not vary with air pressure.  The density of fuel, being nearly
incompressible, also does change with air pressure.  Therefore, the float
switch should NOT behave any differently at altitude than at sea level.
Keith Hallsten


----- Original Message ----- 
From: "Jim Sower" <canarder at frontiernet.net>
To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
Sent: Friday, February 18, 2005 12:09 PM
Subject: Re: REFLECTOR: FUEL FEED & Vents--blinking warning


> <... at altitude when the relative flotation is lessened ...>
>
> You've lost me here ... how and by how much does buoyancy vary with
> altitude?
>
> Rene Dugas wrote:
>
> >I would add away from the turbulence of flow from fuel draining from the
> >wing inlet that may make the switch bob up and down especially at
> >altitude when the relative flotation is lessened.
> >Rene'
> >
> >-----Original Message-----
> >From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
> >Behalf Of Jim Sower
> >Sent: Thursday, February 17, 2005 8:42 PM
> >To: Velocity Aircraft Owners and Builders list
> >Subject: Re: REFLECTOR: FUEL FEED & Vents--blinking warning
> >
> >I would say a half gallon or a gallon down from normal fuel level
> >(depending on whether or not your sump is vented).
> >
> >Tom Martino wrote:
> >
> >
> >
> >>Where exactly should the sensor n the header tank be placed?
> >>
> >>
> >>
> >>-----Original Message-----
> >>*From:* John Dibble [mailto:aminetech at bluefrog.com]
> >>*Sent:* Thursday, February 17, 2005 10:00 AM
> >>*To:* Velocity Aircraft Owners and Builders list
> >>*Subject:* Re: REFLECTOR: FUEL FEED & Vents--blinking warning
> >>
> >>
> >>
> >>Sometimes my light comes on at high altitude.  Sometimes it stays on
> >>for up to an hour.  Sometimes during that hour it will occasionally
> >>blink "off".  Sometimes it just blinks on occasionally.  Sometimes it
> >>doesn't come on for several months.  It never comes on when I am at
> >>low altitude.  I'm thinking of re-labeling it as a warning that O2 is
> >>needed.
> >>
> >>John
> >>
> >>SlvEgl99 at aol.com wrote:
> >>
> >>
> >>
> >>> I have a question that may be related to venting.  At high altitude
> >>>(10,000 or so) the sump low fuel warning light occasionally blinks on
> >>>
> >>>
> >
> >
> >
> >>>and off. There is no other indication of low fuel, plenty in the
> >>>mains and no fuel starvation indications of any sort. This has
> >>>happened only twice in the hours I have flown, and as soon as I
> >>>return to a lower altitude there is no problem. The sump low fuel
> >>>sensor is located in the front, top center of the tank, about 1 1/4"
> >>>below the top in the position called for in the builders manual. I
> >>>suppose that the higher nose attitude resulting from flight at this
> >>>altitude may result in this condition, but I would like to hear other
> >>>
> >>>
> >
> >
> >
> >>>thoughts. Bob Wood
> >>>
> >>>
> >>>
> >>>
> >>>
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