Millimeter of Mercury

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millimeter of mercury

[′mil·ə‚mēd·ər əv ′mər·kyə·rē]
A unit of pressure, equal to the pressure exerted by a column of mercury 1 millimeter high with a density of 13.5951 grams per cubic centimeter under the standard acceleration of gravity; equal to 133.322387415 pascals; it differs from the torr by less than 1 part in 7,000,000. Abbreviated mmHg. Also known as millihg.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Millimeter of Mercury


(also torr), a subsidiary unit of pressure used in measurements of atmospheric pressure, partial pressure of water vapor, and high vacuums. The notations are as follows: Russian, mm rt. St.; international, mm Hg. A millimeter of mercury is equal to the hydrostatic pressure of a column of mercury 1 mm high at a density of 13.5951 × 103 kg/m3 and a gravitational accelerationg = 9.80665 m/sec2. The relationships between the millimeter of mercury and other units of pressure are as follows: 1 mm Hg = 133.322 newtons per sq m = 1.35951 × 10−3 kilogram-force per sq cm = 13.5951 mm H2O.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.