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(Redirected from Venturi pump)
An 'aspirator', also called an 'ejector' or 'filter pump', is a device that produces vacuum
by means of the Venturi effect. In an aspirator,
fluid (liquid or gaseous) flows through a tube which then narrows. When the tube
narrows, the fluid's speed increases, and because of the Venturi effect, its
pressure decreases. Vacuum is taken from this point.
The cheap and simple
'water aspirator' is the most common type of aspirator. It is used in
chemistry and biology laboratories and consists
of a tee fitting which is attached to a faucet and has a hose barb at one
side. The flow of water passes through the straight portion of the tee, which has a restriction at the intersection, where the hose barb is attached. The vacuum hose
should be connected to this barb.
If a liquid is used as the working fluid, the
strength of the vacuum produced is limited by the vapor pressure of the
liquid (for water, 24 mmHg at 25 degrees Celsius.) If a gas is used,
however, this restriction does not exist. The industrial 'steam ejector' (also called
the 'steam jet ejector', 'steam aspirator', or 'steam jet aspirator')
uses steam as a working fluid.
In order to avoid using too much steam, a single steam ejector stage is generally
not used to generate vacuum below approximately 75 mmHg.[1] To generate higher vacuum, multiple stages are used; in a two-stage
steam ejector, for example, the second stage provides vacuum for the waste steam output
by the first stage. Condensers may be used between stages to reduce the load on the
later stages. Steam ejectors with two, three, four, five and six stages may be
used to produce vacuums down to 20 mmHg, 2.5 mmHg, 0.3 mmHg, 0.03 mmHg,
and 0.003 mmHg, respectively.1
The 'air ejector' or 'venturi pump' is similar to the steam ejector but uses
high-pressure air as the working fluid. Multistage air ejectors can be used, but since air cannot easily be condensed at room temperature, an air ejector is usually limited to two or three stages.[2]
Medical aspirators are small suction machines used to remove mucus and other bodily fluids from a patient. They are often designed to be portable for use in ambulances and nursing homes, and can run on AC/DC or battery power. Major manufacturers include Allied Healthcare (under the Gomco brand) and Impact.
1. High Vacuum Pumping Equipment, B. D. Power, New York: Reinhold Publishing Corporation, 1966, chapter 4.
2. Air Ejectors Cheaper Than Steam
★ Ejector
★ Steam injector
★ Diffusion pump
★ Vacuum pump
★ Steam ejector
An 'aspirator', also called an 'ejector' or 'filter pump', is a device that produces vacuum
by means of the Venturi effect. In an aspirator,
fluid (liquid or gaseous) flows through a tube which then narrows. When the tube
narrows, the fluid's speed increases, and because of the Venturi effect, its
pressure decreases. Vacuum is taken from this point.
| Contents |
| Operation |
| Medical aspirators |
| References |
| See also |
Operation
The cheap and simple
'water aspirator' is the most common type of aspirator. It is used in
chemistry and biology laboratories and consists
of a tee fitting which is attached to a faucet and has a hose barb at one
side. The flow of water passes through the straight portion of the tee, which has a restriction at the intersection, where the hose barb is attached. The vacuum hose
should be connected to this barb.
If a liquid is used as the working fluid, the
strength of the vacuum produced is limited by the vapor pressure of the
liquid (for water, 24 mmHg at 25 degrees Celsius.) If a gas is used,
however, this restriction does not exist. The industrial 'steam ejector' (also called
the 'steam jet ejector', 'steam aspirator', or 'steam jet aspirator')
uses steam as a working fluid.
In order to avoid using too much steam, a single steam ejector stage is generally
not used to generate vacuum below approximately 75 mmHg.[1] To generate higher vacuum, multiple stages are used; in a two-stage
steam ejector, for example, the second stage provides vacuum for the waste steam output
by the first stage. Condensers may be used between stages to reduce the load on the
later stages. Steam ejectors with two, three, four, five and six stages may be
used to produce vacuums down to 20 mmHg, 2.5 mmHg, 0.3 mmHg, 0.03 mmHg,
and 0.003 mmHg, respectively.1
The 'air ejector' or 'venturi pump' is similar to the steam ejector but uses
high-pressure air as the working fluid. Multistage air ejectors can be used, but since air cannot easily be condensed at room temperature, an air ejector is usually limited to two or three stages.[2]
Medical aspirators
Medical aspirators are small suction machines used to remove mucus and other bodily fluids from a patient. They are often designed to be portable for use in ambulances and nursing homes, and can run on AC/DC or battery power. Major manufacturers include Allied Healthcare (under the Gomco brand) and Impact.
References
1. High Vacuum Pumping Equipment, B. D. Power, New York: Reinhold Publishing Corporation, 1966, chapter 4.
2. Air Ejectors Cheaper Than Steam
See also
★ Ejector
★ Steam injector
★ Diffusion pump
★ Vacuum pump
★ Steam ejector
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