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Pressure gauges measure the increase and reduction of pressure in a contained field. The earliest patent for a tube pressure gauge was issued to France's Eugene Bourdon in 1849. Still in use in the twenty-first century, the popular Bourdon pressure gauge measures different kinds of liquids and gases including steam, water and air. The coiled tube connects to gears measuring pressures up to 100,000 psi (pounds per square inch) of the container. Whether used for industry, medicine, transportation or in the mechanics of everyday life and recreation, the variety of pressure gauges available add to the safety and quality of life of our modern global community.

Air Pressure Gauges

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Air pressure gauges measure the amount of air needed to maintain the optimum use of the object containing this gas. A common container of air is a tire. Using an air pressure gauge ensures the correct amount of air fills the tire for optimum performance. Too little air in a tire eventually makes it flatten while too much air makes it wear unevenly or even explode.

Oil Pressure Gauges

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Machine engines use oil to lubricate the moving parts while in motion to prevent the natural friction from damaging the motor components. Oil pressure gauges indicate safe or unsafe levels of oil.

Differential Pressure Gauges

Differential pressure gauges, such as a liquid-column manometer (measuring vacuum pressures), show the variation in pressure between two points by observing the fluid used in a U-tube. Such instruments contain two entrance ports with each connected to one of the monitored pressure capacities. Using this type of pressure gauge allows operators to monitor pressure at one point rather than having to check two pressure gauges and calculate the difference.

Digital Pressure Gauges

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Used in a variety of industries, digital pressure gauges convert applied pressure into signals that read out in numerical displays. These gauges have pharmaceutical, food processing and automotive applications as well as use for containment and monitoring of hazardous materials.

Diaphragm Pressure Gauges

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Instead of using a liquid level to measure the difference between an unknown and a reference pressure as with the differential pressure gauge, the diaphragm pressure gauge uses the expandable deformation of a diaphragm or membrane. This pressure gauge contains a capsule divided by a diaphragm open to the external targeted (unknown) pressure while the other side of the diaphragm connects to the known pressure. Mechanically, the undesirable pressure difference exhibits with the deflection of the diaphragm from a leveled position.