# pressure gauge

pressure gauge
1. an instrument for measuring the pressure of a gas or liquid.
2. an instrument used to determine the pressure in the bore or chamber of a gun when the charge explodes.
[1860-65]

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Instrument for measuring the condition of a fluid (liquid or gas) that is specified by the force the fluid would apply, when at rest, to a unit area, such as pounds per square inch (psi) or pascals (Pa).

The reading on the gauge, called the gauge pressure, is always the difference between two pressures. When the lower of the pressures is that of the atmosphere, the total (or absolute) pressure is the sum of the gauge and atmospheric pressures.

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instrument for measuring the condition of a fluid (liquid or gas) that is specified by the force that the fluid would exert, when at rest, on a unit area, such as pounds per square inch or newtons per square centimetre.

The reading on a gauge, which is the difference between two pressures, is known as the gauge pressure. If the lower of the pressures is the pressure of the atmosphere, the total, or absolute, pressure is the sum of the gauge and atmospheric pressures.

The simplest device for measuring static pressures up to about 90 pounds per square inch (62 newtons per square cm) is a U-tube manometer (shown in the figure—>), in which one column of a liquid in the tube is open to a region of high pressure and the other column to a region of low pressure. The differential pressure is indicated by the difference in level between the two columns of liquid, and it is calculated as the difference in level multiplied by the density of the liquid. The manometer liquids most commonly used are mercury, oil, alcohol, and water.

The Bourdon-tube gauge, invented about 1850, is still one of the most widely used instruments for measuring the pressure of liquids and gases of all kinds, including steam, water, and air up to pressures of 100,000 pounds per square inch (70,000 newtons per square cm). The device (also shown in the figure—>) consists of a flattened circular tube coiled into a circular arc. One end is soldered to a central block and is open to the fluid whose pressure is to be measured; the other end is sealed and coupled to the pointer spindle. When the pressure inside the tube is greater than the outside pressure, the tube tends to straighten, thus turning the pointer. The pressure is read on a circular scale.

Metal bellows and diaphragms are also used as pressure-sensing elements. Because of the large deflections for small pressure changes, bellows instruments are particularly suitable for pressures below atmospheric. Two corrugated diaphragms sealed at their edges to form a capsule, which is evacuated, are used in aneroid barometers to measure atmospheric pressure (see altimeter).

These instruments employ mechanical linkages and so are primarily useful for measuring static pressures or pressures that change slowly. For rapidly changing pressures, electrical pressure transducers that convert pressure to an electrical signal are more suitable. These include strain gauges; moving contact resistance elements; and inductance, reluctance, capacitative, and piezoelectric devices. Electromechanical transducers (electromechanical transducer), which are used in hydraulic controllers, where speed and power are needed, convert changes in pressure of fluid to electrical signals.

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Universalium. 2010.

### Look at other dictionaries:

• Pressure gauge — Pressure Pres sure (?; 138), n. [OF., fr. L. pressura, fr. premere. See 4th {Press}.] 1. The act of pressing, or the condition of being pressed; compression; a squeezing; a crushing; as, a pressure of the hand. [1913 Webster] 2. A contrasting… …   The Collaborative International Dictionary of English

• pressure gauge — n. a gauge for measuring the pressure of steam, water, gas, etc …   English World dictionary

• pressure gauge — Instrument for measuring the pressure exerted by the contents on its container. Reading in pounds per square inch (psi) above atmospheric pressure. See oil pressure gauge tire pressure gauge …   Dictionary of automotive terms

• pressure gauge — slėgmatis statusas T sritis fizika atitikmenys: angl. manometer; pressure gage; pressure gauge; pressure measuring device vok. Druckmesser, m; Manometer, n rus. измеритель давления, m; манометр, m pranc. manomètre, m; mesureur de pression, m …   Fizikos terminų žodynas

• pressure gauge — manometras statusas T sritis automatika atitikmenys: angl. manometer; pressure gage; pressure gauge vok. Druckmesser, m; Manometer, n rus. манометр, m pranc. manomètre, m …   Automatikos terminų žodynas

• pressure gauge — slėgmatis statusas T sritis Standartizacija ir metrologija apibrėžtis Dujų ir skysčių slėgio matuoklis. atitikmenys: angl. manometer; pressure gage; pressure gauge vok. Druckmesser, m; Druckmessgerät, n; Manometer, n rus. манометр, m pranc.… …   Penkiakalbis aiškinamasis metrologijos terminų žodynas

• pressure gauge — manometras statusas T sritis chemija apibrėžtis Dujų ir skysčių slėgio, didesnio už atmosferinį, matuoklis. atitikmenys: angl. manometer; pressure gage; pressure gauge rus. манометр …   Chemijos terminų aiškinamasis žodynas

• pressure gauge hysteresis — slėgmačio histerezė statusas T sritis Standartizacija ir metrologija apibrėžtis Slėgmačio atsako į poveikį priklausomybė nuo ankstesnių poveikių sekos. atitikmenys: angl. pressure gage hysteresis; pressure gauge hysteresis pranc. hystérésis de… …   Penkiakalbis aiškinamasis metrologijos terminų žodynas

• pressure gauge — noun gauge for measuring and indicating fluid pressure • Syn: ↑pressure gage • Hypernyms: ↑gauge, ↑gage • Hyponyms: ↑manometer, ↑sphygmomanometer …   Useful english dictionary

• pressure gauge — noun Date: 1862 a gauge for indicating fluid pressure …   New Collegiate Dictionary