Как пишется атм

Атмосфера (единица измерения)

Полезное

This page uses content from the English Wikipedia. The original article was at Atmosphere (unit). The list of authors can be seen in the page history. As with the Units of Measurement Wiki, the text of Wikipedia is available under Creative Commons License see Wikia:Licensing.

The standard atmosphere (symbol: atm) is an international reference pressure defined as 101325 Pa and formerly used as a unit of pressure.^[1] For practical purposes it has been replaced by the bar which is 10⁵ Pa.^[1] The difference of about 1% is not significant for many applications, and is within the error range of common pressure gauges.

History[]

In 1954 the 10th Conférence Générale des Poids et Mesures (CGPM) adopted standard atmosphere for general use and affirmed its definition of being precisely equal to 1,013,250 dynes per square centimeter (101 325 Pa).^[2] This value was intended to represent the mean atmospheric pressure at mean sea level at the latitude of Paris, France, and as a practical matter, truly reflects the mean sea level pressure for many of the industrialized nations (those with latitudes similar to Paris).

In chemistry, the original definition of “Standard ^[3]and Pressure” (STP) was a reference temperature of 0 °C (273.15 K) and pressure of 101.325 kPa (1 atm). However, in 1982, the International Union of Pure and Applied Chemistry (IUPAC) recommended that for the purposes of specifying the physical properties of substances, “the standard pressure” should be defined as precisely 100 kPa (exactly 1 bar).^[4]

Pressure units and equivalencies[]

Pressure units

v · d · e	pascal	bar	technical atmosphere	standard atmosphere	torr	pound per square inch
Pa	bar	at	atm	Torr	psi
1 Pa	≡ 1 N/m2	10−5	1.0197×10−5	9.8692×10−6	7.5006×10−3	145.04×10−6
1 bar	105	≡ 106 dyn/cm2	1.0197	0.98692	750.06	14.5037744
1 at	0.980665 ×105	0.980665	≡ 1 kp/cm2	0.96784	735.56	14.223
1 atm	1.01325 ×105	1.01325	1.0332	≡ p0	760	14.696
1 Torr	133.322	1.3332×10−3	1.3595×10−3	1.3158×10−3	= 1 mmHg	19.337×10−3
1 psi	6.895×103	68.948×10−3	70.307×10−3	68.046×10−3	51.715	≡ 1 lbF/in2

A pressure of 1 atm can also be stated as:

≡1.013 25 bar

≡ 101325 pascal (Pa)

≡ 1013.25 millibars (mbar, also mb)

≡ 760 torr ^[B]

≈ 760.001 mm-Hg, 0 °C, subject to revision as more precise measurements of mercury’s density become available ^{[B, C]}

≈ 29.9213 in-Hg, 0 °C, subject to revision as more precise measurements of mercury’s density become available ^[C]

≈ 1.033 227 452 799 886 kgf/cm²

≈ 1.033 227 452 799 886 technical atmosphere

≈ 1033.227 452 799 886 cm–H₂O, 4 °C ^[A]

≈ 406.782 461 732 2385 in–H₂O, 4 °C ^[A]

≈ 14.695 948 775 5134 pounds-force per square inch (psi)

≈ 2116.216 623 673 94 pounds-force per square foot (psf)

Notes:

^A This is the customarily-accepted value for cm–H₂O, 4 °C. It is precisely the product of 1 kg-force per square centimeter (one technical atmosphere) times 1.013 25 (bar/atmosphere) divided by 0.980 665 (one gram-force). It is not accepted practice to define the value for water column based on a true physical realization of water (which would be 99.997 495% of this value because the true maximum density of Vienna Standard Mean Ocean Water is 0.999 974 95 kg/l at 3.984 °C). Also, this “physical realization” would still ignore the 8.285 cm–H₂O reduction that would actually occur in a true physical realization due to the vapor pressure over water at 3.984 °C.

^B Torr and mm-Hg, 0°C are often taken to be identical. For most practical purposes (to 5 significant digits), they are interchangeable.

^C NIST value of 13.595 078(5) g/ml assumed for the density of Hg at 0 °C

Other applications[]

Scuba divers and others use the word atmosphere and «atm» in relation to pressures that are relative to mean atmospheric pressure at sea level (1.013 bar). For example, a partial pressure of oxygen is calibrated typically using air at sea level, so is expressed in units of atm.

The old European unit technical atmosphere (at) is roughly equal to the gauge pressure under 10 m of water; 1 at = 98066.5 Pa.

See also[]

• Standard conditions for temperature and pressure
• Atmospheric pressure
• Bar

References[]

1. ↑ ^{1.0 1.1} British Standard BS 350:2004 Conversion Factors for Units
2. ↑ BIPM Definition of the standard atmosphere
3. ↑ Temperature
4. ↑ IUPAC.org, Gold Book, Standard Pressure

This page uses content from the English Wikipedia. The original article was at Atmosphere (unit). The list of authors can be seen in the page history. As with the Units of Measurement Wiki, the text of Wikipedia is available under Creative Commons License see Wikia:Licensing.

The standard atmosphere (symbol: atm) is an international reference pressure defined as 101325 Pa and formerly used as a unit of pressure.^[1] For practical purposes it has been replaced by the bar which is 10⁵ Pa.^[1] The difference of about 1% is not significant for many applications, and is within the error range of common pressure gauges.

History[]

In 1954 the 10th Conférence Générale des Poids et Mesures (CGPM) adopted standard atmosphere for general use and affirmed its definition of being precisely equal to 1,013,250 dynes per square centimeter (101 325 Pa).^[2] This value was intended to represent the mean atmospheric pressure at mean sea level at the latitude of Paris, France, and as a practical matter, truly reflects the mean sea level pressure for many of the industrialized nations (those with latitudes similar to Paris).

In chemistry, the original definition of “Standard ^[3]and Pressure” (STP) was a reference temperature of 0 °C (273.15 K) and pressure of 101.325 kPa (1 atm). However, in 1982, the International Union of Pure and Applied Chemistry (IUPAC) recommended that for the purposes of specifying the physical properties of substances, “the standard pressure” should be defined as precisely 100 kPa (exactly 1 bar).^[4]

Pressure units and equivalencies[]

Pressure units

v · d · e	pascal	bar	technical atmosphere	standard atmosphere	torr	pound per square inch
Pa	bar	at	atm	Torr	psi
1 Pa	≡ 1 N/m2	10−5	1.0197×10−5	9.8692×10−6	7.5006×10−3	145.04×10−6
1 bar	105	≡ 106 dyn/cm2	1.0197	0.98692	750.06	14.5037744
1 at	0.980665 ×105	0.980665	≡ 1 kp/cm2	0.96784	735.56	14.223
1 atm	1.01325 ×105	1.01325	1.0332	≡ p0	760	14.696
1 Torr	133.322	1.3332×10−3	1.3595×10−3	1.3158×10−3	= 1 mmHg	19.337×10−3
1 psi	6.895×103	68.948×10−3	70.307×10−3	68.046×10−3	51.715	≡ 1 lbF/in2

A pressure of 1 atm can also be stated as:

≡1.013 25 bar

≡ 101325 pascal (Pa)

≡ 1013.25 millibars (mbar, also mb)

≡ 760 torr ^[B]

≈ 760.001 mm-Hg, 0 °C, subject to revision as more precise measurements of mercury’s density become available ^{[B, C]}

≈ 29.9213 in-Hg, 0 °C, subject to revision as more precise measurements of mercury’s density become available ^[C]

≈ 1.033 227 452 799 886 kgf/cm²

≈ 1.033 227 452 799 886 technical atmosphere

≈ 1033.227 452 799 886 cm–H₂O, 4 °C ^[A]

≈ 406.782 461 732 2385 in–H₂O, 4 °C ^[A]

≈ 14.695 948 775 5134 pounds-force per square inch (psi)

≈ 2116.216 623 673 94 pounds-force per square foot (psf)

Notes:

^A This is the customarily-accepted value for cm–H₂O, 4 °C. It is precisely the product of 1 kg-force per square centimeter (one technical atmosphere) times 1.013 25 (bar/atmosphere) divided by 0.980 665 (one gram-force). It is not accepted practice to define the value for water column based on a true physical realization of water (which would be 99.997 495% of this value because the true maximum density of Vienna Standard Mean Ocean Water is 0.999 974 95 kg/l at 3.984 °C). Also, this “physical realization” would still ignore the 8.285 cm–H₂O reduction that would actually occur in a true physical realization due to the vapor pressure over water at 3.984 °C.

^B Torr and mm-Hg, 0°C are often taken to be identical. For most practical purposes (to 5 significant digits), they are interchangeable.

^C NIST value of 13.595 078(5) g/ml assumed for the density of Hg at 0 °C

Other applications[]

Scuba divers and others use the word atmosphere and «atm» in relation to pressures that are relative to mean atmospheric pressure at sea level (1.013 bar). For example, a partial pressure of oxygen is calibrated typically using air at sea level, so is expressed in units of atm.

The old European unit technical atmosphere (at) is roughly equal to the gauge pressure under 10 m of water; 1 at = 98066.5 Pa.

See also[]

• Standard conditions for temperature and pressure
• Atmospheric pressure
• Bar

References[]

1. ↑ ^{1.0 1.1} British Standard BS 350:2004 Conversion Factors for Units
2. ↑ BIPM Definition of the standard atmosphere
3. ↑ Temperature
4. ↑ IUPAC.org, Gold Book, Standard Pressure

From Wikipedia, the free encyclopedia

Atmosphere
Unit of	Pressure
Symbol	atm
Conversions
1 atm in …	… is equal to …
SI units	101.325 kPa
US customary units	14.69595 psi
other metric units	1.013250 bar

The standard atmosphere (symbol: atm) is a unit of pressure defined as 101325 Pa. It is sometimes used as a reference pressure or standard pressure. It is approximately equal to Earth’s average atmospheric pressure at sea level.^[1]

History[edit]

The standard atmosphere was originally defined as the pressure exerted by 760 mm of mercury at 0 °C (32 °F) and standard gravity (g_n = 9.80665 m/s²).^[2] It was used as a reference condition for physical and chemical properties, and was implicit in the definition of the Celsius temperature scale, which defined 100 °C (212 °F) as the boiling point of water at this pressure. In 1954, the 10th General Conference on Weights and Measures (CGPM) adopted standard atmosphere for general use and affirmed its definition of being precisely equal to 1013250 dynes per square centimetre (101325 Pa).^[3] This defined both temperature and pressure independent of the properties of particular substance. In addition, the CGPM noted that there had been some misapprehension that it «led some physicists to believe that this definition of the standard atmosphere was valid only for accurate work in thermometry.»^[3]

In chemistry and in various industries, the reference pressure referred to in standard temperature and pressure was commonly 1 atm (101.325 kPa) but standards have since diverged; in 1982, the International Union of Pure and Applied Chemistry recommended that for the purposes of specifying the physical properties of substances, standard pressure should be precisely 100 kPa (1 bar).^[4]

Pressure units and equivalencies[edit]

Pressure units

v t e	Pascal	Bar	Technical atmosphere	Standard atmosphere	Torr	Pound per square inch
(Pa)	(bar)	(at)	(atm)	(Torr)	(lbf/in2)
1 Pa	—	1 Pa = 10−5 bar	1 Pa = 1.0197×10−5 at	1 Pa = 9.8692×10−6 atm	1 Pa = 7.5006×10−3 Torr	1 Pa = 0.000145037737730 lbf/in2
1 bar	105	—	= 1.0197	= 0.98692	= 750.06	= 14.503773773022
1 at	98066.5	0.980665	—	0.9678411053541	735.5592401	14.2233433071203
1 atm	≡ 101325	≡ 1.01325	1.0332	—	760	14.6959487755142
1 Torr	133.322368421	0.001333224	0.00135951	1/760 ≈ 0.001315789	—	0.019336775
1 lbf/in2	6894.757293168	0.068947573	0.070306958	0.068045964	51.714932572	—

A pressure of 1 atm can also be stated as:

≡ 101325 pascals (Pa)

≡ 1.01325 bar

≈ 1.033 kgf/cm²

≈ 1.033 technical atmosphere

≈ 10.33 m H₂O, 4 °C^{[n 1]}

≈ 760 mmHg, 0 °C, subject to revision as more precise measurements of mercury’s density become available^{[n 1][n 2]}

≡ 760 torr (Torr)^{[n 3]}

≈ 29.92 inHg, 0 °C, subject to revision as more precise measurements of mercury’s density become available^{[n 2]}

≈ 406.782 in H₂O, 4 °C^{[n 1]}

≈ 14.6959 pounds-force per square inch (lbf/in²)

≈ 2116.22 pounds-force per square foot (lbf/ft²)

= 1 ata (atmosphere absolute).

The ata unit is used in place of atm to indicate the total pressure of the system, compared to a vacuum.^[5] For example, an underwater pressure of 3 ata would mean that this pressure includes 1 atm of air pressure and thus 2 atm due to the water.

Notes[edit]

See also[edit]

• Standard temperature and pressure
• Atmospheric pressure
• International Standard Atmosphere

References[edit]

From Wikipedia, the free encyclopedia

Atmosphere
Unit of	Pressure
Symbol	atm
Conversions
1 atm in …	… is equal to …
SI units	101.325 kPa
US customary units	14.69595 psi
other metric units	1.013250 bar

The standard atmosphere (symbol: atm) is a unit of pressure defined as 101325 Pa. It is sometimes used as a reference pressure or standard pressure. It is approximately equal to Earth’s average atmospheric pressure at sea level.^[1]

History[edit]

The standard atmosphere was originally defined as the pressure exerted by 760 mm of mercury at 0 °C (32 °F) and standard gravity (g_n = 9.80665 m/s²).^[2] It was used as a reference condition for physical and chemical properties, and was implicit in the definition of the Celsius temperature scale, which defined 100 °C (212 °F) as the boiling point of water at this pressure. In 1954, the 10th General Conference on Weights and Measures (CGPM) adopted standard atmosphere for general use and affirmed its definition of being precisely equal to 1013250 dynes per square centimetre (101325 Pa).^[3] This defined both temperature and pressure independent of the properties of particular substance. In addition, the CGPM noted that there had been some misapprehension that it «led some physicists to believe that this definition of the standard atmosphere was valid only for accurate work in thermometry.»^[3]

In chemistry and in various industries, the reference pressure referred to in standard temperature and pressure was commonly 1 atm (101.325 kPa) but standards have since diverged; in 1982, the International Union of Pure and Applied Chemistry recommended that for the purposes of specifying the physical properties of substances, standard pressure should be precisely 100 kPa (1 bar).^[4]

Pressure units and equivalencies[edit]

Pressure units

v t e	Pascal	Bar	Technical atmosphere	Standard atmosphere	Torr	Pound per square inch
(Pa)	(bar)	(at)	(atm)	(Torr)	(lbf/in2)
1 Pa	—	1 Pa = 10−5 bar	1 Pa = 1.0197×10−5 at	1 Pa = 9.8692×10−6 atm	1 Pa = 7.5006×10−3 Torr	1 Pa = 0.000145037737730 lbf/in2
1 bar	105	—	= 1.0197	= 0.98692	= 750.06	= 14.503773773022
1 at	98066.5	0.980665	—	0.9678411053541	735.5592401	14.2233433071203
1 atm	≡ 101325	≡ 1.01325	1.0332	—	760	14.6959487755142
1 Torr	133.322368421	0.001333224	0.00135951	1/760 ≈ 0.001315789	—	0.019336775
1 lbf/in2	6894.757293168	0.068947573	0.070306958	0.068045964	51.714932572	—

A pressure of 1 atm can also be stated as:

≡ 101325 pascals (Pa)

≡ 1.01325 bar

≈ 1.033 kgf/cm²

≈ 1.033 technical atmosphere

≈ 10.33 m H₂O, 4 °C^{[n 1]}

≈ 760 mmHg, 0 °C, subject to revision as more precise measurements of mercury’s density become available^{[n 1][n 2]}

≡ 760 torr (Torr)^{[n 3]}

≈ 29.92 inHg, 0 °C, subject to revision as more precise measurements of mercury’s density become available^{[n 2]}

≈ 406.782 in H₂O, 4 °C^{[n 1]}

≈ 14.6959 pounds-force per square inch (lbf/in²)

≈ 2116.22 pounds-force per square foot (lbf/ft²)

= 1 ata (atmosphere absolute).

The ata unit is used in place of atm to indicate the total pressure of the system, compared to a vacuum.^[5] For example, an underwater pressure of 3 ata would mean that this pressure includes 1 atm of air pressure and thus 2 atm due to the water.

Notes[edit]

See also[edit]

• Standard temperature and pressure
• Atmospheric pressure
• International Standard Atmosphere

References[edit]

Единицы измерений, переводные таблицы и формулы

Units, Conversion Tables, and Formulas

Единицы измерения давления / Pressure 

Па, паскаль	кПа, килопаскаль	МПа, мегапаскаль	кгс/см², ат, техническая атмосфера	атм,  физическая атмосфера
Pa, pascal	kPa, kilopascal	MPa, megapascal	kgf/cm² или kp/cm², at, technical atmosphere	аtm,  atmosphere

бар	PSI или psi (фунт/кв. дюйм), фунт-сила на квадратный дюйм	мм рт. ст., миллиметр ртутного столба	мм вод. ст., миллиметр водяного столба
bar	PSI или psi (pounds/square inch или lbf/in²), pound-force per square inch	1 mm Hg	1 mm of water

Паскаль (Па, Pa)

Паскаль (Па, Pa) – единица измерения давления в Международной системе единиц измерения (система СИ). Единица названа в честь французского физика и математика Блеза Паскаля.

Паскаль равен давлению, вызываемому силой, равной одному ньютону (Н), равномерно распределённой по нормальной к ней поверхности площадью один квадратный метр:

1 паскаль (Па) ≡ 1 Н/м²

Кратные единицы образуют с помощью стандартных приставок СИ:

1 МПа (1 мегапаскаль) = 1000 кПа (1000 килопаскалей)

Атмосфера (физическая, техническая)

Атмосфера — внесистемная единица измерения давления, приблизительно равная атмосферному давлению на поверхности Земли на уровне Мирового океана.

Существуют две примерно равные друг другу единицы с таким названием:

1. Физическая, нормальная или стандартная атмосфера (атм, atm) — в точности равна 101 325 Па или 760 миллиметрам ртутного столба.

2. Техническая атмосфера (ат, at, кгс/см²) — равна давлению, производимому силой 1 кгс, направленной перпендикулярно и равномерно распределённой по плоской поверхности площадью 1 см² (98 066,5 Па).

   1 техническая атмосфера = 1 кгс/см² («килограмм-сила на сантиметр квадратный»). // 1 кгс = 9,80665 ньютонов (точно) ≈ 10 Н; 1 Н ≈ 0,10197162 кгс ≈ 0,1 кгс

На английском языке килограмм-сила обозначается как kgf (kilogram-force) или kp (kilopond) – килопонд, от латинского pondus, означающего вес.

Заметьте разницу: не pound (по-английски «фунт»), а pondus.

На практике приближенно принимают: 1 МПа = 10 атмосфер, 1 атмосфера = 0,1 МПа.

Бар

Бар (от греческого βάρος — тяжесть) — внесистемная единица измерения давления, примерно равная одной атмосфере. Один бар равен 105 Н/м² (или 0,1 МПа).

Соотношения между единицами давления

1 МПа = 10 бар = 10,19716 кгс/см² = 145,0377 PSI = 9,869233 (физ. атм.) =7500,7 мм рт.ст.

1 бар = 0,1 МПа = 1,019716 кгс/см² = 14,50377 PSI = 0,986923 (физ. атм.) =750,07 мм рт.ст.

1 ат (техническая атмосфера) = 1 кгс/см² (1 kp/cm², 1 kilopond/cm²) = 0,0980665 МПа = 0,98066 бар = 14,223

1 атм (физическая атмосфера) = 760 мм рт.ст.= 0,101325 МПа = 1,01325 бар = 1,0333 кгс/см²

1 мм ртутного столба = 133,32 Па =13,5951 мм водяного столба

Объемы жидкостей и газов / Volume

л (литр)	куб.м (кубический метр)	куб.см (кубический сантиметр)	кубический фут	кубический дюйм	галлон (США)	галлон (Англия)
l (liter)	cubic meter или cbm	cc или ccm	cubic feet или cu ft	cubic inch, cubic in, cu inch, cu in	gl или gallon (US)	gl или gallon (UK, Imperial)

1 gl (US) = 3,785 л

1 gl (Imperial) = 4,546 л

1 cu ft = 28,32 л = 0,0283 куб.м

1 cu in = 16,387 куб.см

Скорость потока / Flow

л/с (литр в секунду)	л/мин (литр в минуту)	куб.м/час (кубический метр в час)	кубический фут в минуту
l/s (liter/second)	l/min (liter/minute)	cbm/h (cubic meter/hour)	CFM или cfm (cubic feet/minute)

1 л/с = 60 л/мин = 3,6 куб.м/час = 2,119 cfm

1 л/мин = 0,0167 л/с = 0,06 куб.м/час = 0,0353 cfm

1 куб.м/час = 16,667 л/мин = 0,2777 л/с = 0,5885 cfm

1 cfm (кубический фут в минуту) = 0,47195 л/с = 28,31685 л/мин = 1,699011 куб.м/час

Пропускная способность / Valve flow characteristics

Коэффициент (фактор) расхода Kv

Flow Factor – Kv

Основным параметром запорного и регулирующего органа является коэффициент расхода Kv. Коэффициент расхода Kv показывает объем воды в куб.м/час (cbm/h) при температуре 5-30ºC, проходящей через затвор с потерей напора в 1 бар.

Коэффициент расхода Cv

Flow Coefficient – Cv

В странах с дюймовой системой измерений используется коэффициент Cv. Он показывает, какой расход воды в галлон/мин (gallon/minute, gpm) при температуре 60ºF проходит через арматуру при перепаде давления на арматуре в 1 psi.

Cv = 1,16 Kv

Kv = 0,853 Cv

Кинематическая вязкость / Viscosity

сСт  (сантистокс)	м²/с (квадратный метр в секунду)
cSt	m²/s

м²/с – единица кинематической вязкости в системе СИ

Стокс – единица кинематической вязкости в системе СГС

1 сСт = 1 мм²/с = 0,000001 м²/с

1 м²/с = 1000000 сСт

Единицы длины / Length

м (метр)	мм (миллиметр)	фут	дюйм
m	mm	ft (feet)	in (inch)

1 ft = 12 in = 0,3048 м

1 in = 0,0833 ft = 0,0254 м = 25,4 мм

1 м = 3,28083 ft = 39,3699 in

Единицы силы / Force

Н (ньютон)	кгс (килограмм-сила)	фунт-сила
N (newton)	kp (kilogram force)	lbf (pound force)

1 Н = 0,102 кгс = 0,2248 lbf

1 lbf = 0,454 кгс = 4,448 Н

1 кгс = 9,80665 Н (точно) ≈ 10 Н; 1 Н ≈ 0,10197162 кгс ≈ 0,1 кгс

На английском языке килограмм-сила обозначается как kgf (kilogram-force) или kp (kilopond) – килопонд, от латинского pondus, означающего вес. Обратите внимание: не pound (по-английски «фунт»), а pondus.

Единицы массы / Mass

г (грамм)	кг (килограмм)	фунт	унция
g	kg	lb (pound)	oz (ounce)

1 фунт = 16 унций = 453,59 г

            Момент силы (крутящий момент) / Torque

1 Нм (ньютон-метр)	1 кгсм (килограмм-сила-метр)	фунт-сила-фут
N * m	kp * m или kgf * m	lbf * ft

1 кгс . м = 9,81 Н . м = 7,233 фунт-сила-фут (lbf * ft)

Единицы измерения мощности / Power

Некоторые величины:

Ватт (Вт, W, 1 Вт = 1 Дж/с), лошадиная сила (л.с. – рус., hp или HP – англ., CV – франц., PS – нем.)

Соотношение единиц:

В России и некоторых других странах 1 л.с. (1 PS, 1 CV) = 75 кгс* м/с = 735,4988 Вт

В США, Великобритании и других странах 1 hp = 550 фут*фунт/с = 745,6999 Вт

Температура / Temperature

°C	K	°F
Градус Цельсия Celsius	Градус Кельвина Kelvin	Градус Фаренгейта Fahrenheit

Температура по шкале Фаренгейта:

[°F] = [°C] × 9⁄5 + 32

[°F] = [K] × 9⁄5 − 459,67

Температура по шкале Цельсия:

[°C] = [K] − 273,15

[°C] = ([°F] − 32) × 5⁄9

Температура по шкале Кельвина:

[K] = [°C] + 273.15

[K] = ([°F] + 459,67) × 5⁄9

Эта информация в формате doc.