FLUID POWER HANDBOOK
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VACUUM
COMPONENTS Vacuum is pressure that is lower than atmospheric — 14.7 psia at sea level. In a vacuum system, the difference between atmospheric and vacuum pressure creates the ability to lift, hold, move and generally perform work. There are two types of vacuum applications: closed, or nonporous; and open, or porous. In a closed system, removing air progressively decreases the air density within the sealed, confined space and creates a vacuum. In an open system, a vacuum unit must remove more gas molecules than are able to leak back into the system. Vacuum is typically divided into three areas of application, depending on the level of vacuum required. Lowlevel vacuum applications are typically those requiring high
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Vacuum Components 7-19_FPW Vs3.indd 92
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flows and low force. These systems are primarily serviced by blowers. Screen printing on cloth is one application that falls into this range. The majority of industrial vacuum falls within the range of 6 to 29.5 in.-Hg. Application examples include pick-and-place and thermoforming. Scientific or process applications encompass the deepest levels — approaching a near-perfect 29.92 in.-Hg. Flow in this range is minimal. Examples of applications are ion implantation and space simulation. The vacuum generators that evacuate air and create the required low pressure come in an extensive array of types, sizes, designs and efficiencies to suit widely ranging applications. Two basic types are electric-motor-driven vacuum pumps and vacuum ejectors.
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7/15/19 10:17 AM
