David, "I measured actual fuel flow (ran pump into a bucket) and
determined it is 41 gph."
The maximum operating flow through the forward flow sensor would be
slightly smaller than 41 gph - the difference between 300 hPa and 0 hPa
in the pump diagram is between 1 and 2 gph.
I agree that the return flow is 0 (engine off) to 10 gph (115%) smaller
than the forward flow.
Regards, Jan de Jong
On 9/11/2013 9:32 PM, David Joyce wrote:
> <davidjoyce@doctors.org.uk>
>
> 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:
>>
>> 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:
>>>
>>> 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
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> Un/Subscription,
>>>>> Forums!
>>>>> Admin.
>>>>>
>>>>>
>>>>>
>>>>
>>>>
>>>>
>>>
>>>
>>>
>>>
>>>
>>
>>
>> Un/Subscription,
>> Forums!
>> Admin.
>>
>>
>>
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