Example 6-1 Conversion of Inches Vacuum to Absolute

A distillation column is operating at 27.5 inches mercury vacuum, referenced to a 30-inch barometer. This is the pressure at the inlet to the ejector. Due to pressure drop through a vapor condenser and trays of a distillation column, the column bottoms pressure is 23 inches vacu- 

Applied Process Design for Chemical and Petrochemical Plants 

Note This chart gives the usual operating range for each type of vacuum equipment that is, not necessarily the maximum vacuum or minimum pressure it can maintain in an airtight system. Special designs or modifications of these common types are available for even lower pressures than those indicated. 

The common types oi vacuum-producing equipment used terms of both millimeters and inches oi mercury. The right-in commercial processes are indicated on this chart, to- hand scale gives the temperatures at which water or ice 

The central logarithmic scale shows absolute pressures in equipment are necessary to obtain extremely low pressures. 

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