Pressure as exerted by particle collisions inside a closed container
A healthcare worker measuring blood pressure using a sphygmomanometer.
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A digital sphygmomanometer used for measuring blood pressure
Mercury column
Overview of main complications of persistent high blood pressure
The effects of an external pressure of 700 bar on an aluminum cylinder with 5 mm wall thickness
Cardiac systole and diastole
Water escapes at high speed from a damaged hydrant that contains water at high pressure
Blood flow velocity waveforms in the central retinal artery (red) and vein (blue), measured by laser Doppler imaging in the eye fundus of a healthy volunteer.
Low-pressure chamber in Bundesleistungszentrum Kienbaum, Germany
Schematic of pressures in the circulation
A schematic representation of the arterial pressure waveform over one cardiac cycle. The notch in the curve is associated with closing of the aortic valve.
Taking blood pressure with a sphygmomanometer

Blood pressure (BP) is the pressure of circulating blood against the walls of blood vessels.

- Blood pressure

Blood pressure is measured in millimetres of mercury in most of the world, and lung pressures in centimetres of water are still common.

- Pressure
Pressure as exerted by particle collisions inside a closed container

3 related topics

Alpha

Mercury barometer

Millimetre of mercury

Mercury barometer

A millimetre of mercury is a manometric unit of pressure, formerly defined as the extra pressure generated by a column of mercury one millimetre high, and currently defined as exactly 133.322 pascals.

Blood pressure, measured with a sphygmomanometer

Example of the widely used Bourdon pressure gauge

Pressure measurement

Analysis of an applied force by a fluid on a surface.

Analysis of an applied force by a fluid on a surface.

Example of the widely used Bourdon pressure gauge
Checking tire pressure with a spring and piston tire-pressure gauge
Natural gas pressure gauge
A pressure gauge reading in psi (red scale) and kPa (black scale)
A pressure gauge in action
The difference in fluid height in a liquid-column manometer is proportional to the pressure difference:
Ring balance manometer
A McLeod gauge, drained of mercury
Membrane-type manometer
An original 19th century Eugene Bourdon compound gauge, reading pressure both below and above ambient with great sensitivity
Indicator side with card and dial
Mechanical side with Bourdon tube
Mechanical details
A pile of pressure capsules with corrugated diaphragms in an aneroid barograph
Application Schematic
Pirani vacuum gauge (open)
Bayard–Alpert hot-cathode ionization gauge
Penning vacuum gauge (open)
Dead-weight tester. This uses known calibrated weights on a piston to generate a known pressure.

Pressure is typically measured in units of force per unit of surface area.

Blood pressure is measured in millimetres of mercury (see torr) in most of the world, central venous pressure and lung pressures in centimeters of water are still common, as in settings for CPAP machines.

Table of Hydraulics and Hydrostatics, from the 1728 Cyclopædia

Hydrostatics

Branch of fluid mechanics that studies the condition of the equilibrium of a floating body and submerged body "fluids at hydrostatic equilibrium and the pressure in a fluid, or exerted by a fluid, on an immersed body".

Branch of fluid mechanics that studies the condition of the equilibrium of a floating body and submerged body "fluids at hydrostatic equilibrium and the pressure in a fluid, or exerted by a fluid, on an immersed body".

Table of Hydraulics and Hydrostatics, from the 1728 Cyclopædia

It is also relevant to geophysics and astrophysics (for example, in understanding plate tectonics and the anomalies of the Earth's gravitational field), to meteorology, to medicine (in the context of blood pressure), and many other fields.

However, fluids can exert pressure normal to any contacting surface.