The 914 does not have a low flow rate. It pumps around 20 gal per hour from the
tank and returns all of that minus what the engine used back to the tank. Feed
is around 20 gal/hr and return is about 15 gal/hr at cruise. At idle it's almost
20 gal/hr return.
---- David Joyce <davidjoyce@doctors.org.uk> wrote:
>
> Alan, I go along with that. My 914/twin Floscan set up has
> worked nicely without any sort of jet. The only relevant
> stipulation I can remember is that there should be a
> reasonable length of fairly straight hose leading into
> each Floscan as sharp corners will produce turbulence and
> false readings. One of the key points with the Floscan I
> believe is that even if its spinner jams it will not
> significantly impede flow. It seems a bad idea to put
> anything in the flow if you don't have to.
> Regards, David Joyce, G-XSDJ
>
>
> "rampil" <ira.rampil@gmail.com> wrote:
> ><ira.rampil@gmail.com>
> >
> > Alan,
> >
> >Floscan makes 3 models of the 201 sender for varying
> >expected mean
> > flow rates of gasoline. The appropriate unit for the
> >914 is the 201A
> > model which handles 0.3 - 30 gal per hour.
> >
> > If a jet is added, at least in my imagination of what a
> >"jet" or orifice might
> > be, it will add turbulence and reduce accuracy of the
> >flow turbine. I could
> > not find a reference to such an addition in the FloScan
> >site. Further, in a
> > 914 application, the meaningful flow regime is roughly 3
> >- 7 gal/hour, well
> > within the linear range of system. Does it really matter
> >if the measured
> > flow rate at idle power (less than 2 gal/hr) is slightly
> >off?
> >
> > The only place where the flow rates are less than that
> >is in the return line
> > to the tank. In my 912s application, the return flow is
> >unmeasured, but
> > very small, since my measured forward flow rate are
> >right at what Rotax
> > predicts in the manual. It is much less than the LAA
> >posited rate of 0.8
> > gal/hr through the 0.35mm orifice.This was after I
> >independently
> > calibrated my Floscan at three different flow rates.
> >Perhaps the LAA
> > used a higher than Rotax max pressure head of 5 psi
> >through the orifice?
> > The slight apparent increase in fuel flow rate (by not
> >measuring the return
> > flow and subtracting it in the totalizer) seems to me a
> >a safety feature.
> >
> > BTW, any additional "jet" in the return line, if that is
> >what you were
> > contemplating is a direct violation of the engine
> >install instructions for the
> > 914 which requires a low resistance path bach to the
> >tank after the
> > pressure regulator.
> >
> > The return flow rate situation with the 914 may be a bit
> >different than
> > with the 912s, though the pressures and the return
> >orifice are the same.
> >
> > I recognize that if the LAA tells you that you must have
> >return flow measured, if measuring flow at all, you must
> >comply.
> >
> > It is just my opinion that trying to measure flow rates
> >under 0.5 gal/hr will
> > be inherently inaccurate with the Floscan 201A in an
> >aircraft environment
> > and isnot worth the trouble and expense. On the other
> >hand, many
> > builders have this feature installed.
> >
> > Best of luck!
> >
> > --------
> > Ira N224XS
> >
> >
> >
> >
> > Read this topic online here:
> >
> > http://forums.matronics.com/viewtopic.php?p=408424#408424
> >
> >
> >
> >
> >
> >
> >
> >Un/Subscription,
> >Forums!
> >Admin.
> >
> >
> >
>
>
>
>
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