Let's figure out how the pressure is measured

In life, we often encounter situations when it becomes necessary to measure pressure: arterial, atmospheric or pressure of compressed air or gas in a pipe. Let's see, what is this physical quantity. And immediately the following question arises: what is the measurement of the pressure? It turns out that there are several types of units of measure applied to this physical quantity. In this article, we will analyze what pressure is measured. So, let's start by looking at each of these units.

The officially recognized International SI system is the pressure unit Pascal (Pa), its derivatives are kilopascal (kPa) and megapascal (MPa). One Pascal is equal to the following ratio: 1 Pa = 1 N / m ² . However, in different industries, different pressure units are used. For example, in determining the gas capacity and the flow of compressed air (in compressor technology), several completely different units of measurement can be used.

We will analyze the measurement of the pressure of gas and air. The main unit used is a cubic meter per minute of time (m ³ / min). Often, you can find such units as a liter per minute (l / min) or atmospheric pressure (atm), and in English-speaking countries can use cubic foot per minute - cubic foot perminute, or CFM. Let's consider the ratio of these quantities. 1 l / min corresponds to 0.001 m ³ / min, and 1 CFM is equal to 28.3168 l / min, or 0.02832 m ³ / min. Accordingly, 1 m ³ / min is 35.314 CFM. Very often, the performance is driven for absorption either under normal conditions (1 atm at 200 ° C). In this case, before the unit of measurement, put the letter "n", which means normal conditions. For example, 10 nm ³ / min.

Also for measuring the pressure, such units can be used: mm Hg. Art. (Torr) - a millimeter of mercury; Atm. - physical atmosphere; At. - technical atmosphere; bar. In English-speaking countries , a value such as pound per square inch-PSI (pounds per square inch) can be used.

Consider the ratio of the basic units of pressure measurement: 1 megapascal is 10 bar or 7500.7 milimeters of mercury, or 9.8692 physical atmospheres, 10.197 technical atmospheres, and 145.04 PSI.

So we dismantled the measurement of pressure in various directions of technology. And what devices are used to measure such physical quantities?

These mechanisms are classified according to the type of measured pressure (for example, atmospheric, excess or rarefied, that is vacuum), and, of course, according to the principle of action (liquid, membrane, electric, spring and combined). The most important parameter, which is characterized by the device for measuring air pressure - is the accuracy class. There are many such mechanisms. Here are the main devices that are most often used in measuring air pressure:

• Barometer-aneroid, serves to measure atmospheric pressure;
• Barothermohygrometer, also used to measure atmospheric pressure;
• Liquid pressure gauges - used for measuring the difference in pressure;
• Analog and digital manometers.

To summarize, let's say that knowledge about pressure units can be useful to any modern person.