VAPOR LOCK IN AIRPLANE FUEL SYSTEM.
Fuel is necessary
for
running an airplane
engine. Fuel mixes
with air in
combustion chamber of
engine, then burns
and produces power.
This fuel in
combustion chamber, sprayed
in atomized form.
Fuel system of
engine consists of
fuel tank, fuel
lines, engine driven
pumps etc.
Unfortunately , fuel
have a tendency to
vaporize in the
line or associated
fuel system for
one or more
operational reason. This
premature vaporization causes
the restriction of
fuel flow in
whole fuel system
and vapor lock occurs. This
is a dangerous
phenomena, and engine
may stop running
completely.
Reason behind
vapor lock are
many, like fuel temperature
rise,
turbulence of fuel
or low fuel pressure. Airplane
fly at high
altitude, where atmospheric
pressure is low,
this tend to vaporize
the
fuel, and fuel
lines get vapor
locked. Also engine
heat may cause
fuel line heat up
and fuel get
vaporize. For fuel turbulence, it
mixes with air
in fuel tank ,
and this air
try to separate
from fuel in
sharp bend of fuel
lines or in the
steep rise area
of fuel line.
This, in turn create air
pocket in lines,
and flow of fuel
partially or completely
restricted.
To avoid
vapor lock several
measures are taken
by engine manufacturer
and fuel supplier.
Fuel volatility is reduced
by fuel manufacturer
at the time of
fuel production. Engine
manufacturer always try
to reduce sharp
bend and steep
line in fuel
system , thus reduces
vapor pocket formation. Fuel lines
always
design
to keep away from
engine
heat area. If
fuel in the
system kept in
pressure, it reduces
the tendency of
vapor lock, so
booster pump is
used in the
system. Booster pump
keeps the pressure
on fuel line,
and nullified the
vapor lock in
system, when fuel
passes through engine
driven pump, this system passes
vapor back to
fuel tank, and ultimately
releases the
vapor through
fuel tank vent,
to atmosphere.
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