Some standard content:
National Metrology Technical Specification of the People's Republic of China JJF 1012—2007
Humidity and Moisture Metrological Termsatd Their Definitions
Promulgated on November 21, 2007
Implementation on May 21, 2008
Promulgated by the General Administration of Quality Supervision, Inspection and Quarantine JF 1012-—2007
Humidity and Moisture Metrological Terms and Their Definitions
JJF 1012—2007
Replaces JJF1012—1987
This specification was approved by the General Administration of Quality Supervision, Inspection and Quarantine on November 21, 2007, and came into effect on May 21, 2008.
Responsible unit: National Technical Committee for Physical and Chemical Metrology Main drafting unit: China National Institute of Metrology Participating drafting unit: Wang Hai Institute of Metrology and Testing Technology This specification is interpreted by the National Technical Committee for Physical and Chemical Metrology Main drafters of this specification:
JJF 1012--2007
Li Zhanyuan (China National Institute of Metrology) Yu Jia Drafters:
Ren Changqing (China National Institute of Metrology) Yi Hong (China National Institute of Metrology)
Zhang Wendong (Shanghai Institute of Metrology and Testing Technology) Scope · +
Terms and definitions of condensation measurement...
3 Terms and definitions of moisture measurement
JJF1012—2007
Appendix A Symbols and units of commonly used terms and terms for humidity and moisture measurement (1)
1 Scope
JJF 1012—2007
Terms and definitions of humidity and moisture measurement This specification specifies the commonly used terms and definitions of humidity and moisture measurement. 2 Terms and definitions of humidity measurement
2.1 Water vapor
Also called water vapor. The gaseous state of water, formed by the vaporization or sublimation of ice.
2.2 Dry gas
Equivalent air without water vapor
Note! Absolutely free of water
2.3 Wet
Dry gas and water vapor
2.4 Air
Dry gas is a compound without any existence
.
Reversible air.
Not containing water vapor is
2.5 Pot air
Dry air and
2.6 Saturated
gas composed of
turdtion
Water vapor and ice reach a dynamic phase
2.7 Saturated wet gas
At a given temperature
Note: At a certain temperature, please
2.8 The absorption of water vapor
Wurated gas
This reaches a dynamic phase equilibrium
Environment and mixed gas, alcohol point value
bsorption @f
Water molecules enter the material through osmotic pressure 2.9 Adsorption of water vapor
er vapour
Pogption dr water
Water molecules attached to the surface of an object
2.10 Desorption of water vapor
Water molecules detach from the surface of an object or an object
2.11 Humidity
The content of water vapor in the body.
2.12 Mass mixing ratiomixing ratio
Relative.
MEFROLOGY
The opposite of absorption or adsorption.
The ratio of the mass of water vapor in wet air to the mass of dry air, also known as the mixing ratio, Note: The humidity standard, the gravimetric hygrometer, is established based on the definition of mass mixing ratio. m
Wu Zhong: my
The mass of water vapor, kg:.
(kg/kg)
m—mass of humid air, kg.
JJF 1012—2007
2.13 Absolute humidity (also known as volumetric moisture concentration) absolute hutnidity The mass of water vapor in a unit volume of humid air, expressed in,. d.
Or: V-volume of humid air, m2.
2.14 Relative humidity relative humidity (kg/m)
The percentage of the mole fraction of water vapor in humid air to the mole fraction of saturated water vapor under the same temperature and pressure conditions, or the ratio of the partial pressure of water vapor in humid air to the saturated water vapor pressure at the same temperature, expressed in U. U=「
× 100 (%RH)
Where: ,—--the mole fraction of water vapor, mol/mol; - the mole fraction of saturated water vapor, mol/mol. 2.15 Water vapor pressurewatervapourpressureThe pressure of water vapor in a gas (volume V, temperature T) when it exists alone under the same V and T conditions. It is also called water vapor partial pressure and is represented by e. 2.16 Saturated water vapor pressuresaturation waler vapour pressureThe water vapor pressure when water vapor and the water (or ice) surface are in phase equilibrium at a certain temperature. Saturated water vapor pressure is represented by e.
Note: The simple calculation formula for the water vapor pressure relative to the water surface is: Ine,( T) = n611,2 + 243.12+ T17.62T
The simple calculation formula for the water vapor pressure relative to the ice surface is: Ine,(T) = In611.2 + 272.62+ T22.46 T
In the above formula, T is the temperature of the water surface or ice surface (), e is the saturated water vapor pressure (value). 2.17 Dew-point temperature When the gas is cooled under isobaric conditions, the gas temperature when the water vapor in the gas condenses into water and reaches a phase equilibrium state is the dew-point temperature of the gas.
2.18 Frost-point temperature When the gas is cooled under isobaric conditions, the gas temperature when the water vapor in the gas condenses into frost and reaches a phase equilibrium state is the frost-point temperature of the gas.
2.19 Molar ratio of wet-gas The ratio of the maximum amount of water vapor in wet gas to the maximum amount of water vapor in wet gas, expressed as (mol/rmol)
In the formula: n, the amount of water vapor, mol; + the amount of gas, molar
the molar fraction of wet-gas wet-gas2.20
JJF 1012--2007
The ratio of the amount of water vapor in the gas to the total amount of wet gas, expressed as W. ,
2.21 specific hurniditymy
(mol/mul)
The ratio of the mass of water vapor in wet gas to the total mass of wet gas, expressed as 4 9 =
2.22 weight ratioweight ratio
Mass mixing ratio, multiplied by 10°, expressed as W. (kg/kg)
W, = 10° r = 10° m
2.23 volume ratiowolume atio
(ag/g)
The ratio of the partial volume of water vapor in wet gas to the partial volume of dry gas, expressed as V, 10 times. x105
Where: .—partial volume of water vapor, m: V.—partial volume of dry gas, ma
2.24Molar content of wet-gas The number of moles of water vapor in a unit volume of wet gas. N=
(mol/m)
2.25Enhaneement factorThe ratio of the molar content of water vapor in the wet gas that can be saturated on the water (or ice) surface to the molar content of saturated water vapor at the same temperature.
2.26Humidity elementhuidityelement
When the humidity changes, the physical parameters, chemical parameters or other parameters of the device show corresponding changes. Such a device is called an integral element.
2.27 Humidity sensor Humidity sensor is composed of humidity sensitive elements and other (electrical or non-electrical) components, and can output electrical or non-electrical signals to the supporting instruments.
2.28 Humidity transmitter Humidity Iranisrnitter Humidity measurement device that converts humidity signals into standard analog or mathematical signals. 2.29 Response time Response time
The response characteristics of humidity sensitive elements or humidity sensors to changes in the humidity of the measured gas, generally the equilibrium time required to reach 63% (or 90%) of the humidity change. 2.30 Humidity hysteresis
The maximum degree of non-overlap between the response curves of humidity sensitive elements, humidity sensors (transmitters) and hygrometers in the humidification process and the response curves of humidity dehumidification processes under the same humidity. 3
JJF 1012--2007
2.31 Temperature coefficienttemperature coefficient The ratio of the relative humidity drift value and the temperature difference of the humidity sensitive element, humidity sensor (transmitter) and hygrometer under different temperature conditions in the same relative humidity environment. 2.32 Hygrometershygrometers
Various instruments for measuring gas humidity
2.33 Mechanical hygrometermechanicalthermo-hygrometerUsing hair, other organic polymer materials as humidity sensitive elements, pointer-type or recording-type hygrometers that use mechanical amplification devices to directly indicate relative humidity, and general-purpose meters that use the pressure-free wind-adaptive wet-bulb principle to measure the relative humidity of the environment. Note: The hair after degreasing changes with humidity. This change is magnified and the pointer indicates the relative humidity, or through mechanical and electrical conversion, an electrical signal indicating the relative humidity is generated. 2.34 Gravimetric hygrometer: The gravimetric hygrometer uses a desiccant to completely absorb the decomposed gas and accurately measures the volume or mass of the measured gas at the same time. Note: The measured value of the gravimetric hygrometer is mass. 2.35 Electric ventilator: The weight change after the desiccant is absorbed is a gravimetric table. The dry-wet-bulb principle is used to display the relative humidity of the environment, the charged and radiation-proof tube. Note: Electric ventilators include two types: digital display ventilator and liquid crystal display ordinary electric ventilator. There are also two types: wet bulb temperature, high mercury thermometer and mixed resistance dry bulb temperature? The temperature indicated by the thermometer is the ambient temperature. 2.37 Mixed bulb temperature iemperature
The temperature-sensitive part of the wet-bulb salt needle of the psychrometer is wrapped with degreased gauze and kept moist. It absorbs heat when the water evaporates, thereby
making the temperature of the wet bulb drop
The temperature shown is called the bulb temperature. When in the
state, the wet-bulb thermometer is
degrees, generally known as the ambient temperature) and the dry-bulb temperature (also known as the ambient temperature) and the secret
Note: Knowing the dry-bulb temperaturebzxZ.net
vapor pressure, the relative humidity can be calculated and the coefficient of condensation of water at ambient temperature can be calculated. The coefficient in the process does not depend on many factors such as the instrument structure and usage conditions. Note: Under the condition of 2.5mls wind speed, the constant temperature is -4=6-62310 when the wet bulb freezes, A ~ 5.84 ×10 +1.
METROE
2.39 chilled-mirror dew-pount hygromeler uses a thermoelectric cooler to cool the mirror of the dew point sensor, so that the water vapor in the gas condenses into dew or frost on the mirror of the dew point sensor. The photoelectric system automatically controls the balance so that the dew or frost on the mirror is in equilibrium with the water vapor in the gas. A platinum resistance thermometer is used to accurately measure the temperature of the dew layer or frost layer on the mirror, that is, the dew (frost) point temperature of the gas. The instrument that measures the dew point of the gas based on this principle is called a chilled-mirror precision dew point meter. 2.40 Lithium chloride dewpoint hygrometer is an instrument that measures the dew point of a gas by using the temperature of the salt solution (i.e., equilibrium temperature) when the saturated water vapor pressure of a saturated lithium chloride solution is equal to the water vapor pressure of the gas being measured (when reaching equilibrium). 4
JJF1012—2007
Note: This instrument can measure the humidity of air, oxygen, carbon monoxide, carbon dioxide, hydrocarbons, and other gases that do not react chemically with lithium oxide. The measurement range is generally -60 to -45°C. 2.41 Resistive hygrometer is a variety of hygrometers that use resistive humidity sensors. It uses the characteristic that the resistance value of the humidity sensor changes according to a certain law as the ambient humidity changes to measure humidity. Note: There are many types of resistive humidity sensors, which are mainly classified according to the sensing materials of the humidity-sensitive element: electrolytes, swelling organic polymers, and metal oxide porous porcelain. 2.42 Capacitive hygrometer Various hygrometers using capacitive humidity sensors. There are two types of capacitive humidity sensors: one is a polymer humidity sensor capacitor used to measure relative humidity, and the other is a gold screen oxide humidity sensor for measuring low humidity (dew point below -20°C). Capacitive humidity sensors use the change in dielectric constant caused by the absorption of water vapor by certain humidity-sensitive materials to measure humidity.
2.43 Electrolytic hygrometer When the measured gas flows through an electrolytic cell with a special structure coated with a phosphorus pentoxide film, the water vapor contained in it is absorbed by the phosphorus pentoxide and electrolyzed. When the absorption and electrolysis reach equilibrium, the electrolysis current is proportional to the water vapor content in the gas sample. The humidity of the gas is obtained by measuring the electrolysis current. Note: This instrument can measure the humidity of air, inert gases, hydrocarbons, methane, sulfur hexafluoride and other gases that do not react chemically with phosphorus pentoxide and do not participate in electrolysis. The measuring range is usually below 1 D00 xL/L. 2.44 Infrared hygrometer Infrared hygrometer Water molecules strongly absorb near-infrared light of certain wavelengths. Under certain conditions, the absorption rate obeys the Lambert-Beer law. Hygrometers based on this principle are called infrared hygrometers or near-infrared absorption hygrometers. 2.45 Ultraviolet hygrometer Water vapor has the characteristic of absorbing ultraviolet radiation, and the highest absorption is in the ultraviolet spectrum with a wavelength of 121.56mm. Hygrometers based on this principle are called ultraviolet absorption hygrometers (also known as Lyman-alpha hygrometers). 2.46 Humidity generator A general term for devices that can generate airflow or atmosphere with a constant and known water vapor content under certain conditions. 2.46.1 Saturator
A device that can convert dry gas into saturated wet gas. Note: When the temperature is above (, it is called a water vapor generator; when the temperature is below 0, it is called an ice vapor generator. 2.46.2 Two-pressure humidily generator Two-pressure humidily generator Under certain temperature conditions, the gas is pressurized and saturated in the saturation chamber (device), and then decompressed and expanded in the test chamber. By adjusting the pressure ratio of the saturation chamber and the test chamber, a stable airflow or atmosphere with different humidity can be obtained. 2.46.3 Two-temperature humidity generator Under constant pressure conditions, a gas at a certain temperature is saturated in a saturation chamber (chamber), and then its humidity is increased in the test chamber. According to Dalton's law of partial pressure and the gas state equation, the relative humidity of the gas at a higher temperature can be calculated: By adjusting the temperature of the saturator and the test chamber, an airflow or atmosphere with different humidity can be obtained.4 Mixed-flow humidity generator
JJF1012—2007
Under certain temperature conditions, dry gas and saturated moisture are mixed in different proportions to obtain a stable airflow or atmosphere with different humidity.
2.46,5 Permeation humidity generator Permeation tubes made of organic polymer materials are permeable to water. When the permeability and carrier gas flow are fixed, the water permeability is only related to the temperature. The humidity generator based on this principle is called a permeation mixed humidity generator. Note: A diastatic humidity generator can generate constant humidity gas ranging from several μL to 2 (000 μL/L, which is generally used as a low-range humidity generator.
2.46.6 Saturated salt soluticars When a saturated salt solution reaches equilibrium in a closed container, the water vapor partial pressure above the liquid surface remains constant, that is, the relative humidity is fixed. Different relative humidity environments can be obtained by properly selecting different types of salt. This type of humidity generator is called a saturated salt humidity generator. 2.46.7 Temperature and humidity chamber An environmental experimental equipment that can provide a constant temperature and humidity environment. It can be used to verify or calibrate larger volume temperature and humidity meters and temperature and humidity recorders.
3 Terms and definitions of moisture measurement
3.1 Moisture
The water content in a substance.
3.2 Dry matter Substance
Substance that does not contain water.
3.3 Wet substance
Substance that contains water.
3.4 Moisture content on wet basis The ratio of the mass of water in a wet substance to the mass of the wet substance. 3.5 Moisture content on dry basis The ratio of the mass of water in a wet substance to the mass of the dry substance. 3.6 Water activity
For certain hygroscopic substances (such as food, paper, etc.), when the moisture inside them reaches equilibrium with the relative humidity of the enclosed space surrounding them, the relative humidity value is often called water activity. Note: The water activity value is a value between (10% and 10%, dimensionless, and is not expressed in numbers between % and 100% relative humidity.
3.7 Desiccant
Substance used to absorb water vapor, generally divided into physical absorption and chemical absorption. 3.% Gravimetric moisture meter meler is a type of instrument that places the liquid or solid sample to be tested in a drying device to dehydrate it under certain temperature and pressure conditions, and determines its moisture content by weighing the change in the sample mass before and after drying. Note: Instruments that measure moisture using the oven method, thermal balance method and dry coal agent method are three commonly used gravimetric moisture meters. 3.9 Thermobalance
JJF 1012--2007
The balance tray that holds the sample is placed in a heating furnace, and the water in the sample is evaporated or desorbed at a certain temperature. The moisture content of the substance is determined by weighing the sample weight loss on the balance. 3.10 Karl-Fischer moisture meter Karl-Fischer moisture meter uses the iodine in the Karl Fischer reagent to react quantitatively with water to measure moisture. Note: Karl Fischer moisture determination is divided into two categories, coulometric method and quantitation method. Coulometric moisture meter is suitable for measuring trace moisture. Iodine that reacts quantitatively with water is produced by electrolysis reaction. The electrolyte can be used continuously. Volumetric moisture meter has a faster analysis speed, but Karl Fischer reagent needs to be calibrated frequently. 3.11 Resistive moisture meter It is an instrument that uses the property that the conductivity of a material changes according to a certain law as its moisture content changes. Under certain conditions, it measures moisture by measuring the resistance value (or conductivity value) of the material. 3.12 Capacitive moisture meter It is an instrument that uses the property that the dielectric constant of a material changes according to a certain law as its moisture content changes. Under certain conditions, it measures moisture by measuring the dielectric constant (or capacitance value) of the material. 3.13 Infrared moisture meter Water molecules strongly absorb near-infrared light of certain wavelengths. Under certain conditions, the absorption rate obeys the Lambert-Beer law. Based on this principle, the instrument used to measure the moisture in solids is called an infrared moisture meter. 3,14 Microwave moisture meler The moisture content in the sample has a certain relationship with the dielectric constant. When microwaves pass through the sample, different dielectric constants cause different degrees of attenuation of the microwaves. The moisture content can be determined by the energy loss of the microwaves. Appendix A
JJF 1012—2007
Symbols and units of commonly used terms for measuring astringency and moisture - Water activity ((0~1);
d. Absolute humidity, kg/m:
e——Water vapor pressure, Pa:
Saturated water vapor pressure, Pa;
f——Increase coefficient:
Mass of air, kg
-Mass of water vapor, kg;
-Amount of substance in dry air, mel;| |tt||-amount of water vapor, mol;
N--molar content of water vapor, mal/m; strength of mixed gas, Pa;
specific humidity, kg/kg;
mass mixing ratio, also known as mixing ratio, kg/kg-temperature of water surface or ice surface; or temperature of wet gas, K or C; T
-dew point temperature, K or C;
-frost point temperature, K or C;
U———relative humidity, % RH;
-volume of wet vapor, m:
-partial volume of wet vapor, m\:
-volume ratio:
-partial volume of water vapor, m:
Wweight ratio:
x—mole fraction of saturated water vapor, mol/mol:-mole fraction of water vapor, mol/mol; r
-molar ratio of water vapor, mal/mol.6 Water activity wateractivity
For some substances with hygroscopic properties (such as food, paper, etc.), when the water inside them reaches equilibrium with the relative humidity of the enclosed space around them, the relative humidity value is often called water activity. Note: The water activity value is a value between (1% and 1%, dimensionless, and is not expressed as a number between % and 100% relative humidity.
3.7 Desiccant
Substances used to absorb water vapor are generally divided into physical absorption and chemical absorption. 3.% Gravimetric moisture meler A type of instrument that places the liquid or solid sample to be measured in a drying device to dehydrate it under certain temperature and pressure conditions, and determines its moisture content by weighing the change in the sample mass before and after drying. Note: Instruments that measure moisture using the oven method, thermal balance method and dry coal method are three commonly used gravimetric moisture meters. 3.9 Thermobalance thermobalance
JJF 1012--2007
The balance tray with the sample is placed in a heating furnace. At a certain temperature, the water in the sample is evaporated or desorbed. The weight loss of the sample is measured by the balance to determine the moisture content of the material. 3.10 Karl-Fischer moisture meter Karl-Fischer moisture meter is an instrument that uses the quantitative chemical reaction between iodine in Karl Fischer reagent and water to measure moisture. Note: Karl Fischer moisture determination is divided into two categories, coulometric method and volumetric method. Coulometric moisture meter is suitable for trace moisture determination. The iodine that reacts quantitatively with water is produced by electrolytic reaction: the electrolyte can be used continuously: the volumetric moisture meter has a faster analysis speed, but the Karl Fischer reagent needs to be calibrated frequently. 3.11 Resistive moisture meter It uses the property that the conductivity of a material changes according to a certain law as its moisture content changes. Under certain conditions, it measures the moisture content by measuring the resistance value (or conductivity value) of the material. 3. 12 Capacitive moisture meter Moisture meler is an instrument that uses the property that the dielectric constant of a material changes according to a certain rule as its water content changes. Under certain conditions, it measures the moisture content by measuring the dielectric constant (or capacitance value) of the material. 3.13 Infrared moisture meter Water molecules strongly absorb near-infrared light of certain wavelengths. Under certain conditions, the absorption rate obeys the Lambert-Beer law. The instrument based on this principle for measuring the moisture content in solids is called an infrared moisture meter. 3.14 Microwave (moisture) meter Microwave moisture meler The moisture content in the sample has a certain relationship with the dielectric constant. When microwaves pass through the sample being tested, different dielectric constants cause the microwaves to attenuate to different degrees. The moisture content can be determined by the energy loss of the microwaves. Appendix A
JJF 1012—2007
Symbols and units of commonly used terms for measuring astringency and moisture - water activity ((0~1);
d. Absolute humidity, kg/m:
e——water vapor pressure, Pa:
saturated water vapor pressure, Pa;
f——increase coefficient:
mass of air, kg
-mass of water vapor, kg;
-amount of substance in dry air, mel;| |tt||-amount of water vapor, mol;
N--molar content of water vapor, mal/m; strength of mixed gas, Pa;
specific humidity, kg/kg;
mass mixing ratio, also known as mixing ratio, kg/kg-temperature of water surface or ice surface; or temperature of wet gas, K or C; T
-dew point temperature, K or C;
-frost point temperature, K or C;
U———relative humidity, % RH;
-volume of wet vapor, m:
-partial volume of wet vapor, m\:
-volume ratio:
-partial volume of water vapor, m:
Wweight ratio:
x—mole fraction of saturated water vapor, mol/mol:-mole fraction of water vapor, mol/mol; r
-molar ratio of water vapor, mal/mol.6 Water activity wateractivity
For some substances with hygroscopic properties (such as food, paper, etc.), when the water inside them reaches equilibrium with the relative humidity of the enclosed space around them, the relative humidity value is often called water activity. Note: The water activity value is a value between (1% and 1%, dimensionless, and is not expressed as a number between % and 100% relative humidity.
3.7 Desiccant
Substances used to absorb water vapor are generally divided into physical absorption and chemical absorption. 3.% Gravimetric moisture meler A type of instrument that places the liquid or solid sample to be measured in a drying device to dehydrate it under certain temperature and pressure conditions, and determines its moisture content by weighing the change in the sample mass before and after drying. Note: Instruments that measure moisture using the oven method, thermal balance method and dry coal method are three commonly used gravimetric moisture meters. 3.9 Thermobalance thermobalance
JJF 1012--2007
The balance tray with the sample is placed in a heating furnace. At a certain temperature, the water in the sample is evaporated or desorbed. The weight loss of the sample is measured by the balance to determine the moisture content of the material. 3.10 Karl-Fischer moisture meter Karl-Fischer moisture meter is an instrument that uses the quantitative chemical reaction between iodine in Karl Fischer reagent and water to measure moisture. Note: Karl Fischer moisture determination is divided into two categories, coulometric method and volumetric method. Coulometric moisture meter is suitable for trace moisture determination. The iodine that reacts quantitatively with water is produced by electrolytic reaction: the electrolyte can be used continuously: the volumetric moisture meter has a faster analysis speed, but the Karl Fischer reagent needs to be calibrated frequently. 3.11 Resistive moisture meter It uses the property that the conductivity of a material changes according to a certain law as its moisture content changes. Under certain conditions, it measures the moisture content by measuring the resistance value (or conductivity value) of the material. 3. 12 Capacitive moisture meter Moisture meler is an instrument that uses the property that the dielectric constant of a material changes according to a certain rule as its water content changes. Under certain conditions, it measures the moisture content by measuring the dielectric constant (or capacitance value) of the material. 3.13 Infrared moisture meter Water molecules strongly absorb near-infrared light of certain wavelengths. Under certain conditions, the absorption rate obeys the Lambert-Beer law. The instrument based on this principle for measuring the moisture content in solids is called an infrared moisture meter. 3.14 Microwave (moisture) meter Microwave moisture meler The moisture content in the sample has a certain relationship with the dielectric constant. When microwaves pass through the sample being tested, different dielectric constants cause the microwaves to attenuate to different degrees. The moisture content can be determined by the energy loss of the microwaves. Appendix A
JJF 1012—2007
Symbols and units of commonly used terms for measuring astringency and moisture - water activity ((0~1);
d. Absolute humidity, kg/m:
e——water vapor pressure, Pa:
saturated water vapor pressure, Pa;
f——increase coefficient:
mass of air, kg
-mass of water vapor, kg;
-amount of substance in dry air, mel;| |tt||-amount of water vapor, mol;
N--molar content of water vapor, mal/m; strength of mixed gas, Pa;
specific humidity, kg/kg;
mass mixing ratio, also known as mixing ratio, kg/kg-temperature of water surface or ice surface; or temperature of wet gas, K or C; T
-dew point temperature, K or C;
-frost point temperature, K or C;
U———relative humidity, % RH;
-volume of wet vapor, m:
-partial volume of wet vapor, m\:
-volume ratio:
-partial volume of water vapor, m:
Wweight ratio:
x—mole fraction of saturated water vapor, mol/mol:-mole fraction of water vapor, mol/mol; r
-molar ratio of water vapor, mal/mol.
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