How to convert from millimeters of mercury to pascals. The influence of atmospheric pressure on human health Convert pressure mmHg

About what it is Atmosphere pressure, we are told at school during natural history and geography lessons. We get acquainted with this information and safely throw it out of our heads, rightly believing that we will never be able to use it.

But years later, stress and environmental conditions environment will have a sufficient impact on us. And the concept of “geodependence” will no longer seem nonsense, since pressure surges and headache will begin to poison life. At this moment you will have to remember what it is like in Moscow, for example, in order to adapt to new conditions. And move on with your life.

School basics

The atmosphere that surrounds our planet, unfortunately, literally puts pressure on everything living and inanimate. There is a term to define this phenomenon - atmospheric pressure. This is the force of the air column acting on the area. In the SI system we talk about kilograms per square centimeter. Normal atmospheric pressure (optimal indicators for Moscow have long been known) affects the human body with the same force as a weight weighing 1.033 kg. But most of us don't notice this. There are enough gases dissolved in body fluids to neutralize all unpleasant sensations.

Atmospheric pressure standards in different regions are different. But 760 mmHg is considered ideal. Art. Experiments with mercury turned out to be the most revealing at a time when scientists were proving that air has weight. Mercury barometers are the most common devices for determining pressure. It should also be remembered that ideal conditions, for which the mentioned 760 mm Hg are relevant. Art., is a temperature of 0 ° C and the 45th parallel.

In the international system of units, it is customary to define pressure in Pascals. But for us, the use of mercury column fluctuations is more familiar and understandable.

Relief features

Of course, many factors influence the value of atmospheric pressure. The most significant are the relief and proximity to the magnetic poles of the planet. The norm of atmospheric pressure in Moscow is fundamentally different from the indicators in St. Petersburg; and for residents of some remote village in the mountains, this figure may seem completely abnormal. Already at 1 km above sea level it corresponds to 734 mm Hg. Art.

As already noted, in the region of the earth’s poles the amplitude of pressure changes is much higher than in the equatorial zone. Even during the day, atmospheric pressure varies slightly. Insignificantly, however, only by 1-2 mm. This is due to the difference between day and night temperatures. At night it is usually cooler, which means the pressure is higher.

Pressure and man

For a person, in essence, it does not matter what atmospheric pressure is: normal, low or high. These are very conditional definitions. People tend to get used to everything and adapt. The dynamics and magnitude of changes in atmospheric pressure are much more important. On the territory of the CIS countries, in particular in Russia, there are quite a lot of zones. Often, local residents do not even know about it.

The norm of atmospheric pressure in Moscow, for example, may well be considered as a variable value. After all, every skyscraper is a kind of mountain, and the higher and faster you go up (or go down), the more noticeable the difference will be. Some people may well pass out while riding a high-speed elevator.

Adaptation

Doctors almost unanimously agree that the question “what atmospheric pressure is considered normal” (is it Moscow or any locality planets - not the point) is incorrect in itself. Our body adapts perfectly to life above or below sea level. And if the pressure does not have a detrimental effect on a person, it can be considered normal for the area. Doctors say that the standard atmospheric pressure in Moscow and other major cities is in the range from 750 to 765 mmHg. pillar

The pressure drop is a completely different matter. If within a few hours it rises (falls) by 5-6 mm, people begin to experience discomfort and pain. This is especially dangerous for the heart. Its beating becomes more frequent, and a change in the frequency of breaths leads to a change in the rhythm of oxygen supply to the body. The most common ailments in such a situation are weakness, etc.

Meteor dependence

Normal atmospheric pressure for Moscow may seem like a nightmare to a visitor from the North or the Urals. After all, each region has its own norm and, accordingly, its own understanding of the stable state of the body. And since in life we ​​do not concentrate on exact pressure indicators, weather forecasters always focus on whether the pressure is high or low for a given region.

After all, not every person can boast that they do not notice the corresponding changes. Anyone who cannot call himself lucky in this matter must systematize his feelings during pressure changes and find acceptable countermeasures. Often a cup of strong coffee or tea is enough, but sometimes more is needed. serious help in the form of medicines.

Pressure in the metropolis

Residents of megacities are the most weather-dependent. It is here that a person experiences more stress, lives life at a high pace and experiences environmental degradation. Therefore, knowing what normal atmospheric pressure is for Moscow is vital.

The capital of the Russian Federation is located on the Central Russian Upland, which means that there is a priori a zone of low pressure. Why? It's very simple: the higher you are above sea level, the lower the atmospheric pressure. For example, on the banks of the Moscow River this figure will be 168 m. And the maximum value in the city was recorded in Teply Stan - 255 m above sea level.

It is quite possible to assume that Muscovites will experience abnormally low atmospheric pressure much less frequently than residents of other regions, which, of course, cannot but make them happy. And yet, what atmospheric pressure is considered normal in Moscow? Meteorologists say that it usually does not exceed 748 mm Hg. pillar This means little, since we already know that even a quick ride in an elevator can have a significant impact on a person's heart.

On the other hand, Muscovites do not feel any discomfort if the pressure fluctuates between 745-755 mm Hg. Art.

Danger

But from the point of view of doctors, not everything is so optimistic for the residents of the metropolis. Many experts quite reasonably believe that by working on the upper floors of business centers, people expose themselves to danger. Indeed, in addition to the fact that they live in a zone of low pressure, they also spend almost a third of the day in places with

If we add to this fact violations of the building ventilation system and permanent job air conditioners, it becomes obvious that the employees of such offices are the most incapacitated, sleepy and sick.

Results

Actually, there are a few things to remember. Firstly, there is no single ideal value for normal atmospheric pressure. There are regional standards that can vary significantly in absolute terms. Secondly, the characteristics of the human body make it easy to experience pressure changes if they happen rather slowly. Thirdly, the more healthy image life we ​​lead and the more often we manage to maintain a daily routine (getting up at the same time, long night sleep, following a basic diet, etc.), the less we are susceptible to weather dependence. This means they are more energetic and cheerful.

Atmospheric air has a physical density, as a result of which it is attracted to the Earth and creates pressure. During the development of the planet, both the composition of the atmosphere and its atmospheric pressure changed. Living organisms were forced to adapt to the existing air pressure, changing their physiological characteristics. Deviations from average atmospheric pressure cause changes in a person’s well-being, and the degree of sensitivity of people to such changes varies.

Normal atmospheric pressure

The air extends from the Earth's surface to altitudes of the order of hundreds of kilometers, beyond which interplanetary space begins, while the closer to the Earth, the more the air is compressed under the influence of its own weight, respectively, the atmospheric pressure is highest at the Earth's surface, decreasing with increasing altitude.

At sea level (from which all altitudes are usually measured), at a temperature of +15 degrees Celsius, the atmospheric pressure averages 760 millimeters of mercury (mmHg). This pressure is considered normal (from a physical point of view), which does not mean that this pressure is comfortable for a person under any conditions.

Atmospheric pressure is measured by a barometer, graduated in millimeters of mercury (mmHg), or in other physical units, such as pascals (Pa). 760 millimeters of mercury corresponds to 101,325 pascals, but in everyday life the measurement of atmospheric pressure in pascals or derived units (hectopascals) has not taken root.

Previously, atmospheric pressure was also measured in millibars, which fell out of use and were replaced by hectopascals. Normal atmospheric pressure is 760 mm Hg. Art. corresponds to the standard atmospheric pressure of 1013 mbar.

Pressure 760 mm Hg. Art. corresponds to the action of a force of 1.033 kilograms on each square centimeter of the human body. In total, air presses on the entire surface of the human body with a force of about 15-20 tons.

But a person does not feel this pressure, since it is balanced by air gases dissolved in tissue fluids. This balance is disrupted by changes in atmospheric pressure, which a person perceives as a deterioration in well-being.

For some areas, the average atmospheric pressure differs from 760 mm. Hg Art. So, if in Moscow the average pressure is 760 mm Hg. Art., then in St. Petersburg it is only 748 mm Hg. Art.

At night, the atmospheric pressure is slightly higher than during the day, and at the Earth’s poles, fluctuations in atmospheric pressure are more pronounced than in the equatorial zone, which only confirms the pattern that the polar regions (Arctic and Antarctic) as a habitat are hostile to humans.

In physics, the so-called barometric formula is derived, according to which, with an increase in altitude for every kilometer, atmospheric pressure drops by 13%. The actual distribution of air pressure does not follow the barometric formula quite accurately, since temperature, atmospheric composition, water vapor concentration and other indicators change depending on the altitude.

Atmospheric pressure also depends on the weather, when air masses move from one area to another. All living things on Earth also respond to atmospheric pressure. Thus, fishermen know that the standard atmospheric pressure for fishing is reduced, since when the pressure drops, predatory fish prefer to go hunting.

Impact on human health

Weather-dependent people, and there are 4 billion of them on the planet, are sensitive to changes in atmospheric pressure, and some of them can quite accurately predict weather changes, guided by their well-being.

It is quite difficult to answer the question of what standard of atmospheric pressure is most optimal for places of residence and human life, since people adapt to life in different climatic conditions. Typically the pressure is between 750 and 765 mmHg. Art. does not worsen a person’s well-being; these atmospheric pressure values ​​can be considered within normal limits.

When atmospheric pressure changes, weather-dependent people may feel:

  • headache;
  • vascular spasms with circulatory disorders;
  • weakness and drowsiness with increased fatigue;
  • joint pain;
  • dizziness;
  • feeling of numbness in the limbs;
  • decreased heart rate;
  • nausea and intestinal disorders;
  • shortness of breath;
  • decreased visual acuity.

Baroreceptors located in the body cavities, joints and blood vessels react first to changes in pressure.

When pressure changes, weather-sensitive people experience disturbances in the functioning of the heart, heaviness in the chest, pain in the joints, and in case of digestive problems, also flatulence and intestinal disorders. With a significant decrease in pressure, a lack of oxygen in brain cells leads to headaches.

Also, changes in pressure can lead to mental disorders - people feel anxious, irritated, sleep restlessly, or generally cannot sleep.

Statistics confirm that with sudden changes in atmospheric pressure, the number of crimes, accidents in transport and production increases. The influence of atmospheric pressure on arterial pressure is traced. In hypertensive patients, increased atmospheric pressure can cause a hypertensive crisis with headache and nausea, despite the fact that at this moment clear sunny weather sets in.

On the contrary, hypotensive patients react more sharply to a decrease in atmospheric pressure. The reduced concentration of oxygen in the atmosphere causes circulatory disorders, migraines, shortness of breath, tachycardia and weakness.

Weather sensitivity can be a consequence of an unhealthy lifestyle. The following factors can lead to weather sensitivity or aggravate its severity:

  • low physical activity;
  • poor nutrition with accompanying excess weight;
  • stress and constant nervous tension;
  • poor state of the external environment.

Elimination of these factors reduces the degree of meteosensitivity. Weather-sensitive people should:

  • include foods high in vitamin B6, magnesium and potassium in your diet (vegetables and fruits, honey, lactic acid products);
  • limit the consumption of meat, salty and fried foods, sweets and spices;
  • stop smoking and drinking alcohol;
  • increase physical activity, take walks in the fresh air;
  • organize your sleep, sleep at least 7-8 hours.

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1 pascal [Pa] = 0.00750063755419211 millimeter of mercury (0°C) [mmHg]

Initial value

Converted value

pascal exapascal petapascal terapascal gigapascal megapascal kilopascal hectopascal decapascal decipascal centipascal millipascal micropascal nanopascal picopascal femtopascal attopascal newton per square meter meter newton per square meter centimeter newton per square meter millimeter kilonewton per square meter meter bar millibar microbar dyne per sq. centimeter kilogram-force per square meter. meter kilogram-force per square meter centimeter kilogram-force per square meter. millimeter gram-force per square meter centimeter ton-force (kor.) per sq. ft ton-force (kor.) per sq. inch ton-force (long) per sq. ft ton-force (long) per sq. inch kilopound-force per sq. inch kilopound-force per sq. inch lbf per sq. ft lbf per sq. inch psi poundal per sq. foot torr centimeter of mercury (0°C) millimeter of mercury (0°C) inch of mercury (32°F) inch of mercury (60°F) centimeter of water. column (4°C) mm water. column (4°C) inch water. column (4°C) foot of water (4°C) inch of water (60°F) foot of water (60°F) technical atmosphere physical atmosphere decibar walls on square meter piezo barium (barium) Planck pressure meter sea ​​water foot of sea water (at 15°C) meter of water. column (4°C)

More about pressure

General information

In physics, pressure is defined as the force acting on a unit surface area. If two equal forces act on one larger and one smaller surface, then the pressure on the smaller surface will be greater. Agree, it is much worse if someone who wears stilettos steps on your foot than someone who wears sneakers. For example, if you press the blade of a sharp knife onto a tomato or carrot, the vegetable will be cut in half. The surface area of ​​the blade in contact with the vegetable is small, so the pressure is high enough to cut that vegetable. If you press with the same force on a tomato or carrot with a dull knife, then most likely the vegetable will not cut, since the surface area of ​​the knife is now larger, which means the pressure is less.

In the SI system, pressure is measured in pascals, or newtons per square meter.

Relative pressure

Sometimes pressure is measured as the difference between absolute and atmospheric pressure. This pressure is called relative or gauge pressure and is what is measured, for example, when checking the pressure in car tires. Measuring instruments Often, although not always, it is the relative pressure that is shown.

Atmosphere pressure

Atmospheric pressure is the air pressure at a given location. It usually refers to the pressure of a column of air per unit surface area. Changes in atmospheric pressure affect weather and air temperature. People and animals suffer from severe pressure changes. Low blood pressure causes problems of varying severity in humans and animals, from mental and physical discomfort to fatal diseases. For this reason, aircraft cabins are maintained above atmospheric pressure at a given altitude because the atmospheric pressure at cruising altitude is too low.

Atmospheric pressure decreases with altitude. People and animals living high in the mountains, such as the Himalayas, adapt to such conditions. Travelers, on the other hand, should take necessary measures precautions so as not to get sick due to the fact that the body is not accustomed to such low pressure. Climbers, for example, can suffer from altitude sickness, which is associated with a lack of oxygen in the blood and oxygen starvation of the body. This disease is especially dangerous if you are in the mountains long time. Exacerbation of altitude sickness leads to serious complications such as acute mountain sickness, high altitude pulmonary edema, high altitude cerebral edema and the most acute form mountain sickness The danger of altitude and mountain sickness begins at an altitude of 2400 meters above sea level. To avoid altitude sickness, doctors advise not to use depressants such as alcohol and sleeping pills, drink plenty of fluids, and rise to altitude gradually, for example, on foot rather than by transport. It's also good to eat a large number of carbohydrates, and rest well, especially if the uphill climb happened quickly. These measures will allow the body to get used to the oxygen deficiency caused by low atmospheric pressure. If you follow these recommendations, your body will be able to produce more red blood cells to transport oxygen to the brain and internal organs. To do this, the body will increase the pulse and breathing rate.

First medical aid in such cases is provided immediately. It is important to move the patient to a lower altitude where the atmospheric pressure is higher, preferably to an altitude lower than 2400 meters above sea level. Medicines and portable hyperbaric chambers are also used. These are lightweight, portable chambers that can be pressurized using foot pump. A patient with altitude sickness is placed in a chamber in which the pressure corresponding to a lower altitude is maintained. This camera is used only for first aid medical care, after which the patient must be lowered lower.

Some athletes use low pressure to improve circulation. Typically, this requires training to take place under normal conditions, and these athletes sleep in a low-pressure environment. Thus, their body gets used to high altitude conditions and begins to produce more red blood cells, which, in turn, increases the amount of oxygen in the blood, and allows them to achieve better results in sports. For this purpose, special tents are produced, the pressure in which is regulated. Some athletes even change the pressure in the entire bedroom, but sealing the bedroom is an expensive process.

Spacesuits

Pilots and astronauts have to work in low-pressure environments, so they wear spacesuits that compensate for the low pressure environment. Space suits completely protect a person from the environment. They are used in space. Altitude-compensation suits are used by pilots at high altitudes - they help the pilot breathe and counteract low barometric pressure.

Hydrostatic pressure

Hydrostatic pressure is the pressure of a fluid caused by gravity. This phenomenon plays a huge role not only in technology and physics, but also in medicine. For example, blood pressure is the hydrostatic pressure of blood on the walls of blood vessels. Blood pressure is the pressure in the arteries. It is represented by two quantities: systolic, or the greatest pressure, and diastolic, or the lowest pressure during a heartbeat. Measuring instruments blood pressure called sphygmomanometers or tonometers. The unit of blood pressure is millimeters of mercury.

The Pythagorean mug is an interesting vessel that uses hydrostatic pressure, and specifically the siphon principle. According to legend, Pythagoras invented this cup to control the amount of wine he drank. According to other sources, this cup was supposed to control the amount of water drunk during a drought. Inside the mug there is a curved U-shaped tube hidden under the dome. One end of the tube is longer and ends in a hole in the stem of the mug. The other, shorter end is connected by a hole to the inside bottom of the mug so that the water in the cup fills the tube. The principle of operation of the mug is similar to the operation of a modern toilet cistern. If the liquid level rises above the level of the tube, the liquid flows into the second half of the tube and flows out due to hydrostatic pressure. If the level, on the contrary, is lower, then you can safely use the mug.

Pressure in geology

Pressure is an important concept in geology. Formation is impossible without pressure precious stones, both natural and artificial. High pressure and high temperature are also necessary for the formation of oil from the remains of plants and animals. Unlike gems, which primarily form in rocks, oil forms at the bottom of rivers, lakes, or seas. Over time, more and more sand accumulates over these remains. The weight of water and sand presses on the remains of animal and plant organisms. Over time, this organic material sinks deeper and deeper into the earth, reaching several kilometers below the earth's surface. The temperature increases by 25 °C for every kilometer below the earth's surface, so at a depth of several kilometers the temperature reaches 50–80 °C. Depending on the temperature and temperature difference in the formation environment, natural gas may be formed instead of oil.

Natural gemstones

The formation of gemstones is not always the same, but pressure is one of the main components this process. For example, diamonds are formed in the Earth's mantle, under conditions of high pressure and high temperature. During volcanic eruptions, diamonds move to the upper layers of the Earth's surface thanks to magma. Some diamonds fall to Earth from meteorites, and scientists believe they formed on planets similar to Earth.

Synthetic gemstones

The production of synthetic gemstones began in the 1950s and is gaining popularity in Lately. Some buyers prefer natural gemstones, but artificial stones are becoming more and more popular due to the low price and lack of problems associated with the extraction of natural gemstones. Thus, many buyers choose synthetic gemstones because their extraction and sale is not associated with human rights violations, child labor and the financing of wars and armed conflicts.

One of the technologies for growing diamonds in laboratory conditions is the method of growing crystals at high blood pressure And high temperature. In special devices, carbon is heated to 1000 °C and subjected to pressure of about 5 gigapascals. Typically, a small diamond is used as the seed crystal, and graphite is used for the carbon base. From it a new diamond grows. This is the most common method of growing diamonds, especially as gemstones, due to its low cost. The properties of diamonds grown in this way are the same or better than those of natural stones. The quality of synthetic diamonds depends on the method used to grow them. Compared to natural diamonds, which are often clear, most man-made diamonds are colored.

Due to their hardness, diamonds are widely used in manufacturing. In addition, their high thermal conductivity, optical properties and resistance to alkalis and acids. Cutting tools often coated with diamond dust, which is also used in abrasives and materials. Most of the diamonds in production are of artificial origin due to the low price and because the demand for such diamonds exceeds the ability to mine them in nature.

Some companies offer services for creating memorial diamonds from the ashes of the deceased. To do this, after cremation, the ashes are refined until carbon is obtained, and then a diamond is grown from it. Manufacturers advertise these diamonds as mementos of the departed, and their services are popular, especially in countries with a large percentage financially secure citizens, for example in the USA and Japan.

Method of growing crystals at high pressure and high temperature

The method of growing crystals under high pressure and high temperature is mainly used to synthesize diamonds, but recently this method has been used to improve natural diamonds or change their color. Various presses are used to artificially grow diamonds. The most expensive to maintain and the most complex of them is the cubic press. It is used primarily to enhance or change the color of natural diamonds. Diamonds grow in the press at a rate of approximately 0.5 carats per day.

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; sometimes called "torr" (Russian designation - torr, international - Torr) in honor of Evangelista Torricelli.

The origin of this unit is associated with the method of measuring atmospheric pressure using a barometer, in which the pressure is balanced by a column of liquid. It is often used as a liquid because it has a very high density (≈13,600 kg/m³) and low saturated vapor pressure at room temperature.

Atmospheric pressure at sea level is approximately 760 mmHg. Art. Standard atmospheric pressure is taken to be (exactly) 760 mmHg. Art. , or 101,325 Pa, hence the definition of a millimeter of mercury (101,325/760 Pa). Previously, a slightly different definition was used: the pressure of a column of mercury with a height of 1 mm and a density of 13.5951·10 3 kg/m³ with a free fall acceleration of 9.806 65 m/s². The difference between these two definitions is 0.000014%.

Millimeters of mercury are used, for example, in vacuum technology, in weather reports and in measuring blood pressure. Since in vacuum technology very often pressure is measured simply in millimeters, omitting the words “mercury column”, the natural transition for vacuum engineers to microns (microns) is carried out, as a rule, also without indicating “mercury column pressure”. Accordingly, when a pressure of 25 microns is indicated on a vacuum pump, we are talking about the maximum vacuum created by this pump, measured in microns of mercury. Of course, no one uses a Torricelli pressure gauge to measure such low pressures. To measure low pressures, other instruments are used, for example, McLeod pressure gauge (vacuum gauge).

Sometimes millimeters of water column are used ( 1 mmHg Art. = 13,5951 mm water Art. ). In the USA and Canada, the unit of measurement “inch of mercury” (symbol - inHg) is also used. 1 inHg = 3,386389 kPa at 0 °C.

Pressure units
Pascal
(Pa, Pa)
Bar
(bar, bar)
Technical atmosphere
(at, at)
Physical atmosphere
(atm, atm)
Millimeter of mercury
(mm Hg, mm Hg, Torr, torr)
Water column meter
(m water column, m H 2 O)
Pound-force
per sq. inch
(psi)
1 Pa 1 / 2 10 −5 10.197 10 −6 9.8692 10 −6 7.5006 10 −3 1.0197 10 −4 145.04 10 −6
1 bar 10 5 1 10 6 din/cm 2 1,0197 0,98692 750,06 10,197 14,504
1 at 98066,5 0,980665 1 kgf/cm 2 0,96784 735,56 10 14,223
1 atm 101325 1,01325 1,033 1 atm 760 10,33 14,696
1 mmHg Art. 133,322 1.3332·10 −3 1.3595 10 −3 1.3158 10 −3 1 mmHg Art. 13.595 10 −3 19.337 10 −3
1 m water Art. 9806,65 9.80665 10 −2 0,1 0,096784 73,556 1 m water Art. 1,4223
1 psi 6894,76 68.948 10 −3 70.307 10 −3 68.046 10 −3 51,715 0,70307 1 lbf/in 2

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Notes

Excerpt characterizing Millimeter of mercury

In October 1805, Russian troops occupied the villages and towns of the Archduchy of Austria, and more new regiments came from Russia and, burdening the residents with billeting, were stationed at the Braunau fortress. The main apartment of Commander-in-Chief Kutuzov was in Braunau.
On October 11, 1805, one of the infantry regiments that had just arrived at Braunau, awaiting inspection by the commander-in-chief, stood half a mile from the city. Despite the non-Russian terrain and situation ( orchards, stone fences, tiled roofs, mountains visible in the distance), to the non-Russian people, looking at the soldiers with curiosity, the regiment had exactly the same appearance as any Russian regiment had, preparing for a review somewhere in the middle of Russia.
In the evening, on the last march, an order was received that the commander-in-chief would inspect the regiment on the march. Although the words of the order seemed unclear to the regimental commander, and the question arose how to understand the words of the order: in marching uniform or not? In the council of battalion commanders, it was decided to present the regiment in full dress uniform on the grounds that it is always better to bow than not to bow. And the soldiers, after a thirty-mile march, did not sleep a wink, they repaired and cleaned themselves all night; adjutants and company commanders counted and expelled; and by morning the regiment, instead of the sprawling, disorderly crowd that it had been the day before during the last march, represented an orderly mass of 2,000 people, each of whom knew his place, his job, and of whom, on each of them, every button and strap was in its place and sparkled with cleanliness . Not only was the outside in good order, but if the commander-in-chief had wanted to look under the uniforms, he would have seen an equally clean shirt on each one and in each knapsack he would have found the legal number of things, “sweat and soap,” as the soldiers say. There was only one circumstance about which no one could be calm. It was shoes. More than half the people's boots were broken. But this deficiency was not due to the fault of the regimental commander, since, despite repeated demands, the goods were not released to him from the Austrian department, and the regiment traveled a thousand miles.
The regimental commander was an elderly, sanguine general with graying eyebrows and sideburns, thick-set and wider from chest to back than from one shoulder to the other. He was wearing a new, brand new uniform with wrinkled folds and thick golden epaulettes, which seemed to lift his fat shoulders upward rather than downward. The regimental commander had the appearance of a man happily performing one of the most solemn affairs of life. He walked in front of the front and, as he walked, trembled at every step, slightly arching his back. It was clear that the regimental commander was admiring his regiment, happy with it, that all his mental strength was occupied only with the regiment; but, despite the fact that his trembling gait seemed to say that, in addition to military interests, the interests of social life and the female sex occupied a significant place in his soul.
“Well, Father Mikhailo Mitrich,” he turned to one battalion commander (the battalion commander leaned forward smiling; it was clear that they were happy), “it was a lot of trouble this night.” However, it seems that nothing is wrong, the regiment is not bad... Eh?

In which the pressure is balanced by a column of liquid. It is often used as a liquid because it has a very high density (≈13,600 kg/m³) and low saturated vapor pressure at room temperature.

Atmospheric pressure at sea level is approximately 760 mmHg. Art. Standard atmospheric pressure is taken to be (exactly) 760 mmHg. Art. , or 101,325 Pa, hence the definition of a millimeter of mercury (101,325/760 Pa). Previously, a slightly different definition was used: the pressure of a column of mercury with a height of 1 mm and a density of 13.5951·10 3 kg/m³ with a free fall acceleration of 9.806 65 m/s². The difference between these two definitions is 0.000014%.

Millimeters of mercury are used, for example, in vacuum technology, in weather reports and in measuring blood pressure. Since in vacuum technology very often pressure is measured simply in millimeters, omitting the words “mercury column”, the natural transition for vacuum engineers to microns (microns) is carried out, as a rule, also without indicating “mercury column pressure”. Accordingly, when a pressure of 25 microns is indicated on a vacuum pump, we are talking about the maximum vacuum created by this pump, measured in microns of mercury. Of course, no one uses a Torricelli pressure gauge to measure such low pressures. To measure low pressures, other instruments are used, for example, McLeod pressure gauge (vacuum gauge).

Sometimes millimeters of water column are used ( 1 mmHg Art. = 13,5951 mm water Art. ). In the USA and Canada, the unit of measurement “inch of mercury” (designation - inHg) is also used. 1 inHg = 3,386389 kPa at 0 °C.

Pressure units
Pascal
(Pa, Pa)
Bar
(bar, bar)
Technical atmosphere
(at, at)
Physical atmosphere
(atm, atm)
Millimeter of mercury
(mm Hg, mmHg, Torr, torr)
Water column meter
(m water column, m H 2 O)
Pound-force
per sq. inch
(psi)
1 Pa 1 / 2 10 −5 10.197 10 −6 9.8692 10 −6 7.5006 10 −3 1.0197 10 −4 145.04 10 −6
1 bar 10 5 1 10 6 din/cm 2 1,0197 0,98692 750,06 10,197 14,504
1 at 98066,5 0,980665 1 kgf/cm 2 0,96784 735,56 10 14,223
1 atm 101325 1,01325 1,033 1 atm 760 10,33 14,696
1 mmHg 133,322 1.3332·10 −3 1.3595 10 −3 1.3158 10 −3 1 mmHg. 13.595 10 −3 19.337 10 −3
1 m water Art. 9806,65 9.80665 10 −2 0,1 0,096784 73,556 1 m water Art. 1,4223
1 psi 6894,76 68.948 10 −3 70.307 10 −3 68.046 10 −3 51,715 0,70307 1 lbf/in 2

see also


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See what “Millimeter of mercury” is in other dictionaries:

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