Ouch; I hadn't thought about that. But I suspect that even a low
pressure pump would damage the tank if the vent is blocked. Thanks
for the data point on the fact that a high pressure pump can be used
effectively as a transfer pump.
Were you using a separate port on the main tank for your transfer
point? My tentative plan is to T into either the regulator return,
or (assuming an effective back/anti-siphon setup), into the main
supply between tank & engine pump. Obviously, the anti-siphon
feature would need to be bullet proof to tap the supply line.
One option I've considered is to use the fuel selector 'normally',
but have all regulator bypass return to a single 'main' tank. This
arrangement is actually used in some certified planes with injected
Continentals, but I'm leery of having my primary engine pump run dry
for even a very short interval as I empty an aux tank. I suppose
that with that arrangement, it would only run dry for a couple of
seconds ( :-> ), so maybe it would work out fine. Any thoughts?
Charlie
On 2/24/2011 2:36 PM, Steven W. Boese wrote:
Charlie,
I
initially had my RV set up with a Facet transfer pump with
an external check valve. The check valve spring was
replaced with a slightly stronger one so that it served both
the anti back flow and anti siphon functions. The high
percentage of the time that the Facet transfer pump was
operating convinced me to change to the type (not the exact
part) of pump you are considering. The pump seemed
reliable but after a couple of instances of transferring
fuel out the receiving tank’s vent in spite of a timer on
the transfer pump, I eliminated the transfer function
altogether. The possibility of applying up to 90 psi to the
receiving tank if its vent malfunctioned did not suit me.
It would not take anywhere near this pressure to fail the
tank. The procedure for leak testing the fuel tanks
cautions not to apply even a couple of psi to them. The
limitation here really was me, though, not the equipment.
Steve
Boese
RV6A
1986 13B NA RD1A EC2
From: Rotary motors in aircraft
[mailto:flyrotary@lancaironline.net] On Behalf Of Charlie
England
Sent: Thursday, February 24, 2011 12:23 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Fwd: Fuel injector pump
cooling??
Anyone see any
issues with one of the automotive in-tank pumps being used
outside the tank? Looking at the overall
pump/pickup/regulator/level sensor/etc assemblies in most
auto fuel tanks, it would appear that the pump itself would
be above the level of the fuel anyway if the tank is less
than 1/4 full.
I've been looking for a Facet transfer pump that has both a
backflow valve & an anti-siphon valve (40257 is one) but
they are very hard to find & expensive when you find
them. During my search, I ran across this:
http://www.amazon.com/gp/product/B000BMBSS0/ref=pd_lpo_k2_dp_sr_3?pf_rd_p=486539851&pf_rd_s=lpo-top-stripe-1&pf_rd_t=201&pf_rd_i=B002YP4Q3Q&pf_rd_m=ATVPDKIKX0DER&pf_rd_r=1JFK34G48EBF5R93EB2Y
The application appears to be 87-98 GM products.
It appears to be very similar to the 'standard' in-line pump
that Tracy supplies, with the exception of plastic components
in the output end. Assuming that it's a positive displacement
gear pump, it should supply both the backflow &
anti-siphon features I desire & at roughly $30 shipped,
it's cheaper than even the cheapest Facet 'solid state'
transfer pumps. I'm hoping that cooling/lube won't be an issue
as long as it isn't run 'dry' for more than a few seconds at
the end of a transfer cycle.
Charlie