 |
Matronics Email Lists
Web Forum Interface to the Matronics Email Lists
|
| View previous topic :: View next topic |
| Author |
Message |
Leland Collins
Joined: 10 Jan 2006
Posts: 21
|
 Posted: Wed Dec 06, 2006 10:14 am Post subject: Spurious Floscan pulses |
 |
|
The pulses from Van's Facet pump cause my EIS 4000 to read 2-3
gallons/hour high, when on. This is so even though the pump is in the
cockpit with about two feet of aluminum tubing and a gascolator between
the electric pump and the Floscan head. I tried installing a Matronics
spherical pulse-dampener in the line but did not like having all the
extra fittings. Has anybody on this list tried replacing the aluminum
tubing with flexible fuel line to dampen the pulses?
Leland
RV9A in the paint shop
| | - The Matronics RV-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?RV-List |
|
_________________
Leland
RV9A
N137LC |
|
| Back to top |
|
 |
charleskaluza(at)verizon.
Guest
|
| Posted: Thu Dec 07, 2006 7:54 am Post subject: Spurious Floscan pulses |
|
|
We have had the same issue on our 6 A. Made calibration of the sender more difficult but not a factor in cross-country flights. I was wondering if the carburetor float and bowl were part of the issue?
Kaluza
144KL
[quote][b]
| | - The Matronics RV-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?RV-List |
|
|
|
| Back to top |
|
|
Leland Collins
Joined: 10 Jan 2006
Posts: 21
|
| Posted: Thu Dec 07, 2006 9:18 am Post subject: Re: Spurious Floscan pulses |
|
|
Kaluza, my monitor shows an increased flow rate when the electric fuel pump is rattling away, and it shows fluctuations in reading of a gallon/hour. As you suggest, he fluctuations are likely due to variations in carburetor float level. I would like to minimize the flow rate increase from the Facet pump.
Leland
| | - The Matronics RV-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?RV-List |
|
|
|
| Back to top |
|
|
sbuc(at)hiwaay.net
Guest
|
| Posted: Thu Dec 07, 2006 10:05 am Post subject: Spurious Floscan pulses |
|
|
Leland Collins wrote:
| Quote: |
<federigo(at)pacbell.net>
Kaluza, my monitor shows an increased flow rate when the electric
fuel pump is rattling away, and it shows fluctuations in reading of a
gallon/hour. As you suggest, he fluctuations are likely due to
variations in carburetor float level. I would like to minimize the
flow rate increase from the Facet pump. Leland
|
The explanation I have heard for the flow rate "increase" while the pump
is running involves the design of the flow sensor. It uses an optical
sensor and rotating vanes in order to send pulses to the flowmeter which
then are counted so flow rate can be calculated. When the pump is
running, it causes the fuel flow to alternate in a forward and backward
motion which causes the sensor to generate extra pulses. I assume a
rotary pump would not cause these errors but those of us with the Facet
diaphragm pump see the error.
I don't see how the fuel level in the carb would vary provided the carb
is receiving adequate flow and the float and needle are functioning
properly.
Sam Buchanan
| | - The Matronics RV-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?RV-List |
|
|
|
| Back to top |
|
|
ronlee(at)pcisys.net
Guest
|
| Posted: Thu Dec 07, 2006 10:40 am Post subject: Spurious Floscan pulses |
|
|
| Quote: | Kaluza, my monitor shows an increased flow rate when the electric fuel
pump is rattling away, and it shows fluctuations in reading of a
gallon/hour. As you suggest, he fluctuations are likely due to variations
in carburetor float level. I would like to minimize the flow rate increase
from the Facet pump.
Leland
|
Don't worry about it. The electric boost pump is only on a short time (a
few minutes).
When I fill up and the amount is within a gallon or less of what the fuel
totalizer
indicates, it is a non-issue. Just calibrate the sensor count over
several fillups
and you will be fine.
Ron Lee
| | - The Matronics RV-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?RV-List |
|
|
|
| Back to top |
|
|
Dale Ensing
Joined: 11 Jan 2006
Posts: 571
Location: Aero Plantation Weddington NC
|
| Posted: Thu Dec 07, 2006 11:38 am Post subject: Spurious Floscan pulses |
|
|
Sam,
Wouldn't the fuel have to be compressible to get a flow alternating between
forward and backward thru the flow sensor when the pump is running? This, of
course, is assuming (as you pointed out) the carburetor float valve is doing
its job so that any head of air in the carb bowl is not being compressed.
Dale Ensing
do not archive
| Quote: | > Kaluza, my monitor shows an increased flow rate when the electric
> fuel pump is rattling away, and it shows fluctuations in reading of a
> gallon/hour. As you suggest, he fluctuations are likely due to
> variations in carburetor float level. I would like to minimize the
> flow rate increase from the Facet pump. Leland
The explanation I have heard for the flow rate "increase" while the pump
is running involves the design of the flow sensor. It uses an optical
sensor and rotating vanes in order to send pulses to the flowmeter which
then are counted so flow rate can be calculated. When the pump is running,
it causes the fuel flow to alternate in a forward and backward motion
which causes the sensor to generate extra pulses. I assume a rotary pump
would not cause these errors but those of us with the Facet diaphragm pump
see the error.
I don't see how the fuel level in the carb would vary provided the carb is
receiving adequate flow and the float and needle are functioning properly.
Sam Buchanan
|
| | - The Matronics RV-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?RV-List |
|
_________________
Dale Ensing
RV-6A
Aero Plantation
Weddington NC |
|
| Back to top |
|
|
Doug Gray
Joined: 10 Jan 2006
Posts: 112
Location: Sydney, Australia
|
| Posted: Thu Dec 07, 2006 12:10 pm Post subject: Spurious Floscan pulses |
|
|
Does the mechanical fuel pump have a spring loaded diaphragm to move the
fuel? If so perhaps the is allowing a small fluid flow with the Facet
pump pulses.
Does the flow sensor have a bi-phase electrical output (ie two outputs
with 90 degree phase shift)? If it does then some extra logic could be
employed to subtract rather than add the reverse flow.
Doug
On Thu, 2006-12-07 at 14:35 -0500, Dale Ensing wrote:
| Quote: |
Sam,
Wouldn't the fuel have to be compressible to get a flow alternating between
forward and backward thru the flow sensor when the pump is running? This, of
course, is assuming (as you pointed out) the carburetor float valve is doing
its job so that any head of air in the carb bowl is not being compressed.
Dale Ensing
do not archive
>> Kaluza, my monitor shows an increased flow rate when the electric
>> fuel pump is rattling away, and it shows fluctuations in reading of a
>> gallon/hour. As you suggest, he fluctuations are likely due to
>> variations in carburetor float level. I would like to minimize the
>> flow rate increase from the Facet pump. Leland
>
>
> The explanation I have heard for the flow rate "increase" while the pump
> is running involves the design of the flow sensor. It uses an optical
> sensor and rotating vanes in order to send pulses to the flowmeter which
> then are counted so flow rate can be calculated. When the pump is running,
> it causes the fuel flow to alternate in a forward and backward motion
> which causes the sensor to generate extra pulses. I assume a rotary pump
> would not cause these errors but those of us with the Facet diaphragm pump
> see the error.
>
> I don't see how the fuel level in the carb would vary provided the carb is
> receiving adequate flow and the float and needle are functioning properly.
>
> Sam Buchanan
|
| | - The Matronics RV-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?RV-List |
|
|
|
| Back to top |
|
|
sbuc(at)hiwaay.net
Guest
|
| Posted: Thu Dec 07, 2006 1:08 pm Post subject: Spurious Floscan pulses |
|
|
Dale, you make a good point about the lack of compressibility of the
fuel, but maybe Doug has hit on the reason for the less than consistent
flow rate indication.
Seems I heard the background info on this matter from RMI, the
manufacturer of the uMonitor in my plane. If I recall the setup
correctly, my monitor sees ~2900 pulses per gallon which is ~6.5 pulses
per second at cruise. If the pump is inducing a couple of pulses per
second, there is our error.
However, all of this is pretty academic since it has practically no
real-world impact on fuel management. Since the pump only runs during
takeoff, landing, and tank change, it has minimal impact on hourly fuel
calculations and reduces this whole exercise to the realm of "merely
curious". 
Sam Buchanan
========================
Doug Gray wrote:
| Quote: |
Does the mechanical fuel pump have a spring loaded diaphragm to move the
fuel? If so perhaps the is allowing a small fluid flow with the Facet
pump pulses.
Does the flow sensor have a bi-phase electrical output (ie two outputs
with 90 degree phase shift)? If it does then some extra logic could be
employed to subtract rather than add the reverse flow.
Doug
On Thu, 2006-12-07 at 14:35 -0500, Dale Ensing wrote:
>
>
> Sam,
> Wouldn't the fuel have to be compressible to get a flow alternating between
> forward and backward thru the flow sensor when the pump is running? This, of
> course, is assuming (as you pointed out) the carburetor float valve is doing
> its job so that any head of air in the carb bowl is not being compressed.
> Dale Ensing
|
| Quote: | >> The explanation I have heard for the flow rate "increase" while the pump
>> is running involves the design of the flow sensor. It uses an optical
>> sensor and rotating vanes in order to send pulses to the flowmeter which
>> then are counted so flow rate can be calculated. When the pump is running,
>> it causes the fuel flow to alternate in a forward and backward motion
>> which causes the sensor to generate extra pulses. I assume a rotary pump
>> would not cause these errors but those of us with the Facet diaphragm pump
>> see the error.
>>
>> I don't see how the fuel level in the carb would vary provided the carb is
>> receiving adequate flow and the float and needle are functioning properly.
>>
>> Sam Buchanan
|
| | - The Matronics RV-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?RV-List |
|
|
|
| Back to top |
|
|
pitts_pilot(at)bellsouth.
Guest
|
| Posted: Thu Dec 07, 2006 8:01 pm Post subject: Spurious Floscan pulses |
|
|
Not being knowledgeable about the specific flow sensor, let me comment
generally. The auto units I'm familiar with use a ball in racetrack to
measure fuel flow. The ball will come between a lamp and photocell,
creating a pulse each revolution round the racetrack. This is an
electrical pulse. The fuel pump, on the other hand, will create a
pressure pulse ......causing variations in the fuel flow ..... but not
directly measureable by the photocell since the pulse is of short
duration. However, if the pulse was high enough and the ball in the
right position under the photocell, it could move forward from under the
photocell on the pressure side (creating the pulse), and flow back under
the photocell (pressure decrease) to create an extra pulse. The timing
would have to be just right in this scenario. I may be totally off base
here, but it's the only way to account for extra pulses caused by the pump.
Linn
do not archive
Sam Buchanan wrote:
| Quote: |
Dale, you make a good point about the lack of compressibility of the
fuel, but maybe Doug has hit on the reason for the less than
consistent flow rate indication.
Seems I heard the background info on this matter from RMI, the
manufacturer of the uMonitor in my plane. If I recall the setup
correctly, my monitor sees ~2900 pulses per gallon which is ~6.5
pulses per second at cruise. If the pump is inducing a couple of
pulses per second, there is our error.
However, all of this is pretty academic since it has practically no
real-world impact on fuel management. Since the pump only runs during
takeoff, landing, and tank change, it has minimal impact on hourly
fuel calculations and reduces this whole exercise to the realm of
"merely curious".
Sam Buchanan
========================
Doug Gray wrote:
>
>
> Does the mechanical fuel pump have a spring loaded diaphragm to move the
> fuel? If so perhaps the is allowing a small fluid flow with the Facet
> pump pulses.
>
> Does the flow sensor have a bi-phase electrical output (ie two outputs
> with 90 degree phase shift)? If it does then some extra logic could be
> employed to subtract rather than add the reverse flow.
>
> Doug
>
> On Thu, 2006-12-07 at 14:35 -0500, Dale Ensing wrote:
>
>>
>>
>> Sam,
>> Wouldn't the fuel have to be compressible to get a flow alternating
>> between forward and backward thru the flow sensor when the pump is
>> running? This, of course, is assuming (as you pointed out) the
>> carburetor float valve is doing its job so that any head of air in
>> the carb bowl is not being compressed.
>> Dale Ensing
>
>>> The explanation I have heard for the flow rate "increase" while the
>>> pump is running involves the design of the flow sensor. It uses an
>>> optical sensor and rotating vanes in order to send pulses to the
>>> flowmeter which then are counted so flow rate can be calculated.
>>> When the pump is running, it causes the fuel flow to alternate in a
>>> forward and backward motion which causes the sensor to generate
>>> extra pulses. I assume a rotary pump would not cause these errors
>>> but those of us with the Facet diaphragm pump see the error.
>>>
>>> I don't see how the fuel level in the carb would vary provided the
>>> carb is receiving adequate flow and the float and needle are
>>> functioning properly.
>>>
>>> Sam Buchanan
>>
|
| | - The Matronics RV-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?RV-List |
|
|
|
| Back to top |
|
|
|
|
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum
|
Powered by phpBB © 2001, 2005 phpBB Group
|
Get Email Distribution Too!
FAQ
Search
Memberlist
Usergroups
Register
Profile
Log in to check your private messages
Log in
