Hi folks, still scratching my head about fuel systems <{{:-)>
Having read the factory description of their ACS gascolator blockage, I
have been asking around about gascolator design, if only to reinforce my
own experience and opinions.
There is a relatively cheap unit on the market, which has its bowl retained
by a bent wire spring. This is prone to allow leaks (embarassing to a
suction system) if not correctly tightened and prone to falling off if over
tightened. I had one on my Long EZ, we used to wire it so that the spring
couldn't let go, as recommended by our local certified engineers.
The strainer is brass wire gauze, quite fine and a bit flexible. I am told
that if it is subjected to debris this tends to form a ball of felt like
material just below the suction outlet of the unit which increases the
pressure drop across the gauze and causes distortion so that the gauze now
pushes up against the outlet hole causing even more blockage.
The size of the holes in the mesh allows bits of fibre, swarf or whatever
to get jammed in as described by Andy in the newsletter.
There are better things around. The Andair mini gascolator for the Rotax
912 series engines uses Teflon coated stainless steel mesh with pore size
of 70 microns. It will not allow water to pass if wet with fuel. The flow
through the filter slows at the face of the mesh which helps rubbish to
fall away. If there is any sign of water or dirt at the daily drain check
it is easy to drop the bowl and check. IMHO the daily preflight drain check
is the best way of avoiding the filter blockages that have caught out too
many Europa people already. Having a second filter and a second
(questionable ) chance also adds the chance of other trouble and since most
of the dirt that is put in with the fuel will go into the reserve side,
which we rarely use, if the main side blocks then the reserve will quite
likely block very soon after.
Tell me if I'm wrong, I like to learn something every day. Helps to replace
the many things I forget.
Graham
|