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Pressure , in the physical sciences , the perpendicular force per unit area, or the stress at a point within a confined fluid . The pressure exerted on a floor by a 42-pound box the bottom of which has an area of 84 square inches is equal to the force divided by the area over which it is exerted; i.e., it is one-half pound per square inch. The weight of the atmosphere pushing down on each unit area of Earth ’s surface constitutes atmospheric pressure , which at sea level is about 15 pounds per square inch. In SI units, pressure is measured in pascals ; one pascal equals one newton per square metre . Atmospheric pressure is close to 100,000 pascals.

The pressure exerted by a confined gas results from the average effect of the forces produced on the container walls by the rapid and continual bombardment of the huge number of gas molecules . Absolute pressure of a gas or liquid is the total pressure it exerts, including the effect of atmospheric pressure. An absolute pressure of zero corresponds to empty space or a complete vacuum .

Measurement of pressures by ordinary gauges on Earth, such as a tire -pressure gauge, expresses pressure in excess of atmospheric. Thus, a tire gauge may indicate a pressure of 30 pounds (per square inch), the gauge pressure. The absolute pressure exerted by the air within the tire, including atmospheric pressure, is 45 pounds per square inch. Pressures less than atmospheric are negative gauge pressures that correspond to partial vacuums.

Pressure , in the physical sciences , the perpendicular force per unit area, or the stress at a point within a confined fluid . The pressure exerted on a floor by a 42-pound box the bottom of which has an area of 84 square inches is equal to the force divided by the area over which it is exerted; i.e., it is one-half pound per square inch. The weight of the atmosphere pushing down on each unit area of Earth ’s surface constitutes atmospheric pressure , which at sea level is about 15 pounds per square inch. In SI units, pressure is measured in pascals ; one pascal equals one newton per square metre . Atmospheric pressure is close to 100,000 pascals.

The pressure exerted by a confined gas results from the average effect of the forces produced on the container walls by the rapid and continual bombardment of the huge number of gas molecules . Absolute pressure of a gas or liquid is the total pressure it exerts, including the effect of atmospheric pressure. An absolute pressure of zero corresponds to empty space or a complete vacuum .

Measurement of pressures by ordinary gauges on Earth, such as a tire -pressure gauge, expresses pressure in excess of atmospheric. Thus, a tire gauge may indicate a pressure of 30 pounds (per square inch), the gauge pressure. The absolute pressure exerted by the air within the tire, including atmospheric pressure, is 45 pounds per square inch. Pressures less than atmospheric are negative gauge pressures that correspond to partial vacuums.

National Instruments offers a wide variety of pressure measurement solutions ranging from simple, secure Wi-Fi devices to high-channel rack-mountable systems. You can integrate all NI pressure measurement systems with other measurements and sensor types because of the modular design. Software options are available for configuration-based loggers as well as full programming environments.

Pressure measurements are one of the fastest growing types of physical measurements. You can make pressure measurements in various mediums using different channel counts. Depending on the desired accuracy, range, and expense, you have several sensor options for measuring pressure. National Instruments offers a wide variety of devices for you to choose from to make pressure measurements.

The how-to guide for most common measurements provides information about making common sensor and signal measurements. Each of the following documents covers the operating principle for the corresponding signal/sensor and offers guidance on how to make that type of measurement. These documents help you understand what you need to know to quickly make your desired measurement.