"MikeR" wrote in message ...

"Blueskies" wrote in message
. com...

"MikeR" wrote in message
...


No wheel in this one (electrical impulses).



Impulses from what?


Ref: http://203.167.230.122/qiss/scripts/FAQFrame.htm


Title: How does the flow transducer work?
Question/Symptom:
How does the flow transducer work?

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Answer/Solution:
NAVMAN flow transducers are of an optical type. Within the transducer
are a transmitter and receiver that output an infrared beam through the body
of the transducer. Inside the transducer is a very precisely dimensioned
turbine running on jewelled bearings. As the fuel flows it spins the turbine
and the blades cut the infrared beam, which transmits a pulsed signal to the
fuel computer.



OK, normal stuff. Thanks for the link. The concern from the other folks is what happens to pressure drop if the (turbine
in this case) wheel seizes up. Usually it will add some pressure drop with a corresponding restriction to the flow, but
the turbine types pass fluid pretty well even if seized...