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Charlie, could you not provide redundancy with a on/off valve between the tanks? If one pump dies, turning the valve on to allow fuel to gravity flow to the tank with the good pump. Redundancy is provided by a pump in each tank. Both run during takeoff and landing. If one dies, switch to the other tank and run it low, then open the valve to get fuel from the tank with the bad pump if you haven't found an airport already.
On Monday, October 27, 2014 6:46 PM, Charlie England <flyrotary@lancaironline.net> wrote:
On 10/27/2014 4:55 PM, Ernest Christley
wrote:
This is the type that I'm referring to:
Is anyone familiar with
electric fuel selector valves as used in
automotive applications. I'm trying to figure
out how they operate. Do they select one line
when power is applied to a solenoid type
plunger, and then the other line is selected
when power isn't applied? Or does a pulse of
power switch them back and forth? If they
maintain the currently selected tank when power
is absent, it seems to me that this could remove
fuel lines and a leak prone selector valve from
a lot of cockpits. Furthermore, the 6 port
models look like they could be plumbed easily to
handle return lines.
The ones I've seen actually use a motor to move the valve (think
screw jack), so they will remain in last position. Reading your
linked item indicates that it works the same way.
'Traditional' engine guys have avoided them in the past because
they're plastic and they require power (and they are an automotive
product, so they can't be reliable ;-) ). They are probably worth
considering, but I'm seriously looking at switching to in-tank
turbine pumps with automotive style PWM control; no return line
needed. Then tank selection would be with a switch on the panel
instead of a valve. Downside is that for total redundancy, I'd need
2 pumps in each tank. They are dirt cheap (<$20 each), but
controllers are around $75 ea and switching gets pretty elaborate if
there are more than 2 tanks.
Charlie
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