Jerry et al.,
Assuming it was possible to find a fuel flow system with a flow transducer
which was accurate at the flow rates you find with a 912, would it be OK
(i.e. work accurately) to locate the transducer in the fuel supply line to
the carburetors, after the fuel return bleed back to the fuel tank, the
objective being that the fuel flow transducer measures the flow to the
carburetors only, and not the return flow. This would remove the need (and
expense) of a differential flow system. What do you think?
Donald Kesterton
#216
G-PATS
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From: Jerry Davis [SMTP:lts@avnet.co.uk]
Subject: Re: Fuel Flow guage
I spoke to one of the fuel computer manufacturers about this
problem. They are looking at a solution but nothing is coming yet. The real
problem is the fuel return flow. I think all of the less expensive flow
meters use impeller or vane type senders which generate frequency/flow
signals. The problem is these devices only operate over reletivley small
ranges. I have several senders here which work well on Rotax engines.
Typically they measure a 10 l/hr or 25 l/hr with very acceptable errors. The
trouble is to have a sensor which measures a high volume you must have a
large jet over the vane or impeller. The same sensor will not generate
enough fluid velocity when the flow rates are low to spin the impeller.
but it may stall at a little less than this flow rate say 4 l/hr. maximum
flow is 23 l/hr giving a range of less than 6:1.
nothing.
Volumetric or displacment meters may be the only solution but they
are expensive and I have no experiance with these devices.
Jerry
lts@avnet.co.uk
http://www.avnet.co.uk/touchdown
----- Original Message -----
From: Michael Dawson
Subject: Fuel Flow guage
Could anyone out there advise me of a reasonably priced fuel
flow guage ? the cheaper one sold by RD has a 1/8th Inch orifice in the
transducer which I understand gives flow problem from time to time - their
expensive one is very expensive as with a 914 you need and extra transducer
and the lot comes to well over 1000.
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