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| Operating Specifications |
| Model |
Model ML /
MLE |
Model SG |
Model HG |
| Motive
Media |
Liquid, Liquid |
Steam,
Air |
Steam,
Air |
| Motive
Pressure (PSIG) |
20-250
20-250 |
60-120 |
20-80 |
| Max.
Vacuum (in Hg) |
29
29 |
24 |
24 |
| Outlet
Pressure (PSIG) |
20
20 |
12 |
20 |
| Applications |
Exhaust,
Evacuate, Prime |
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| There are two major types of applications using eductors to pump gases. These are evacuation and exhausting. |
| Download
Eductors Liquids-Gases Pulling Gas Brochure - PDF |
| |
| Exhausting |
| This application involves removing gases at a continuous
rate from an area while maintaining the pressure at a stable level.
These applications often involve removing gases or fumes that are
continuously recurring. An example would be removing smoke from
a welding or machining area. This process also could be used for
injecting oxygen into a liquid stream. If the gases being
removed have undesirable characteristics, it is possible in some
cases to neutralize them by using a reactive motive fluid. |
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| Evacuation |
 This
application involves pulling gases from a defined volume by pumping
the tank down from a starting pressure to a final lower pressure.
It is generally sized by determining the amount of time it takes
to reduce the pressure in the vessel to the desired final pressure.
Examples of this application would be reducing the pressure in
a reaction vessel to purge it of detrimental gases, or removing
steam from a vessel before opening it to increase operator safety.
A variation of this type of application is the use of eductors to prime piping or a system with liquid. Priming evacuations
may be used to bring the level of liquid up to pump level to
avoid the pump being started dry or to establish a siphon.
 Jacoby Tarbox
eductor models for liquids pumping gases are: ML, MLE; for
gases pumping gases: SG, HG. These models can be used for both
exhausting and evacuation. See the following specifications
tables for operating parameters.
Other models of eductors are available for specific applications.
In some cases, these specialty eductors can pump a suction
volume up to 50 times the motive volume. Most Jacoby Tarbox eductors
are available in sizes from 1/2" through 3" in a
wide variety of materials. Expedited deliveries are possible
if needed. Units are available in sizes up to 12".
Eductors operate on the basic principles of flow dynamics.
This involves taking a high pressure motive stream and
accelerating it through a tapered nozzle to increase the velocity
of the fluid. Gas motives are compressible fluids and are
put through a converging-diverging nozzle. The gas can exceed
the speed of sound. This fluid is then carried on through a
secondary chamber where the friction between the molecules
of it and a secondary gas (generally referred to as the suction
fluid) causes this secondary gas to be pumped. These fluids
are intimately mixed together and discharged from the eductor. |
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| There are three connections common to all eductors: |
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| Eductor MOTIVE Connection |
| This connection is where the power for the eductor
is generated, by increasing the velocity of the motive fluid. The
Jacoby Tarbox nozzle in this section is manufactured to take advantage
of the physical properties of the motive fluid. Eductors with liquid
motives use a converging nozzle, as liquids are not generally compressible.
Eductors with gas motives utilize converging-diverging nozzles
to achieve maximum benefit from the compressibility of the gas.
All Jacoby Tarbox nozzles for eductors have smooth flow paths. Flow paths
with rough surfaces cause eductors to operate less efficiently. |
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| Eductor SUCTION Connection |
| This connection of the eductor is where the pumping
action of the eductor takes place. The motive fluid passes through
the suction chamber, entraining the suction gas as it passes. The
friction between the fluids at the interface of the motive fluid
causes the chamber to be evacuated as the gas in the chamber is
removed. This allows the pressure in the suction vessel to
push additional flow into the suction connection of the eductor.
The high velocity of the motive stream in this section of the eductor
directs the combined fluid toward the discharge section of the
eductor. |
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| Eductor OUTLET Connection |
| As the motive fluid entrains the suction gas, part
of the kinetic energy of the motive fluid is imparted to the suction
gas. This allows the resulting mixture to discharge at an intermediate
pressure. The percentage of the motive pressure that will be recovered
is dependent upon the percentage of motive flow to suction flow
and the amount of vacuum at the suction connection. |
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| Related Links: |
| How to Size Liquid
Motive Eductors for Exhausting Gases Models ML and MLE |
| How to Size Liquid
Motive Eductors for Exhausting Gases Models SG and HG |
| How to Size
Steam or Gas Motive Eductors for Exhausting Gases |
| How to Size
Liquid Motive Eductors for Evacuating Gases |
| How to Size Gas or Steam Motive Eductors for Evacuating |
| How to Correct for Different Gases - Dry Air Equivalent |
| Eductor Reference Tables |
| Dimensional Drawing for Eductors - (PDF) |
| Dimensional Drawing for Flanged Eductors - (PDF) |
| Download
Eductors Liquids-Gases Pulling Gas Brochure - PDF |
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