Jan, I wonder whether he was measuring what came out of
the pump, rather than what came back through the return
hose with the engine not going,
once the fuel had gone through the pressure release
valve., which will be quite a bit less I guess.
Regards, David Joyce, G- XSDJ
Jan de Jong <jan_de_jong@casema.nl> wrote:
><jan_de_jong@casema.nl>
>
> I saved a message by Jim Butcher on a
>blue-mountain-avionics forum where he reported measuring
>a flow of 41 gph into a bucket. The Rotax 914
>installation manual gives 30 gph as the rated flow for 1
>pump at 300 hPa (airbox at sea level pressure) to 25 gph
>at 1000 hPa (airbox at 16000' with full boost). The
>second pump would increase this by a small amount.
>Floscan 201A-6 seems marginal, 201B-6 seems better.
> I bought from Floscan 2 of type 231 ("marine use only"),
>similar to 201B-6 but heavier (steel). And less
>expensive. And no fretting with aluminium adapters...
> Alan, if you have a 914 I believe you might get the 914
>installation manual - it has a flow graph for the pump
>(Pierburg E1F no. 7.21440.78.0).
> And you might check out the Floscan website. There are 2
>aviation pages.
> Regards, Jan de Jong.
>
> On 9/11/2013 7:45 PM, Dean Seitz wrote:
>><daseitz@cfl.rr.com>
>>
>> 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:
>>><davidjoyce@doctors.org.uk>
>>>
>>> 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
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
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>>>> Admin.
>>>>
>>>>
>>>>
>>>
>>>
>>>
>>
>>
>>
>>
>>
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