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eductor

An eductor, also known as an ejector or ejector pump, is a device that uses a high-velocity jet of motive fluid to entrain and transport a second fluid, creating flow without movable mechanical parts. Eductors are widely used to generate vacuum, transfer liquids, or mix chemicals in a simple, compact form.

Principle: The motive fluid passes through a converging-diverging nozzle, increasing velocity and reducing static pressure in

Construction: A typical eductor has a motive-fluid inlet, a nozzle, a mixing chamber, an entrainment inlet, and

Performance and considerations: The entrainment ratio ER is the mass flow of entrained fluid divided by the

Applications: used for vacuum generation in tanks and process lines, liquid transfer and drainage, chemical mixing,

Advantages and limitations: advantages include simplicity, ruggedness, and lack of moving parts; availability of motive fluid;

Related concepts include ejectors and Venturi nozzles.

the
mixing
chamber.
The
low
pressure
draws
in
the
surrounding
fluid
(the
entrained
liquid
or
gas).
The
two
streams
join
and
slow
down
in
a
diffuser,
raising
the
mixture
to
discharge
pressure.
a
discharge
diffuser.
There
are
steam-jet
eductors,
air-jet
eductors,
and
water
eductors,
among
others.
Most
have
no
moving
parts;
performance
is
dominated
by
the
nozzle
design
and
the
backpressure
of
the
receiving
system.
motive-fluid
flow.
Eductors
require
adequate
motive
pressure;
their
suction
lift
is
limited
by
the
pressure
differential
and
backpressure.
Viscosity,
density,
and
surface
tension
affect
efficiency.
Cavitation
and
backflow
are
potential
issues.
spill
cleanup,
ventilation
and
fume
control,
and
other
industrial
processes
where
a
simple,
low-maintenance
pump
with
no
moving
parts
is
advantageous.
ability
to
operate
in
hazardous
environments.
Limitations
include
limited
suction
lift,
sensitivity
to
backpressure,
dependency
on
motive
fluid
supply,
and
lower
efficiency
compared
to
mechanical
pumps
for
some
tasks.