Sa = solubility ratio
ma = mass of air (lbm, kg)
mw = mass of water (lbm, kg)
Solubility of air in water follows Henry's Law - "the amount of air dissolved in a fluid is proportional to the pressure in the system" - and can be expressed as:
c = pg / kH (2)
c= solubility of dissolved gas
kH= proportionality constant depending on the nature of the gas and the solvent
pg= partial pressure of gas (Pa, psi)
The solubility of oxygen in water is higher than the solubility of nitrogen. Air dissolved in water contains approximately 35.6% oxygen compared to 21% in air.
Solubility of air in water - expressed as ratio of absorbed air volume to water volume:
|Gauge Pressure (psig) |
The amount of air dissolved in water - mass of air to volume/mass of water - can be calculated with Henry's law.
Henry Law's Constants at a system temperature of 25oC (77oF)
Partial fraction in Air
Oxygen dissolved in the Water at atmospheric pressure can be calculated as:
co = (1 atm) 0.21 / (756.7 atm/(mol/litre)) (31.9988 g/mol)
~ 0.0089 g/kg
Nitrogen dissolved in the Water at atmospheric pressure can be calculated as:
cn = (1 atm) 0.79 / (1600 atm/(mol/litre)) (28.0134 g/mol)
~ 0.0138 g/kg
Since air mainly consists of Nitrogen and Oxygen - the air dissolved in the water can be calculated as:
ca =(0.0089 g/litre) + (0.0138 g/litre)
= 0.0227 g/litre
~ 0.023 g/kg
Calculating the air dissolved in water for some other pressures at temperature 25oC (77oF) can be summarized to:
|Pressure, abs (atm)||1||2||3||4||5||6|
|Dissolved Air in Water (25oC) (g/kg)||0.023||0.045||0.068||0.091||0.114||0.136|
For maximum deaeration the water should be heated up to 212 oF (100 oC) at atmospheric pressure. This is common in steam systems where fresh water is supplied to the system through a heated deaeration tower on the top of the condensate receiver tank.
It is also common to install deaeration devices on the hot sides of heat exchangers in heating distribution systems to force the dissolved air out of the system.
Note! Since the maximum deaeration is limited by the minimum static pressure and maximum temperature in the system - the best deaeration result is achieved in positions at the hottest and highest levels of the systems - and/or at the suction side of pumps.
Material properties of gases, fluids and solids - densities, specific heats, viscosities and more.
Dry air is a mechanical mixture of nitrogen, oxygen, argon and several other gases in minor amounts.
Air density at pressure ranging 1 to 10 000 bara (14.5 - 145000 psi) and constant selected temperatures.
Online calculator, figures and tables showing density, specific weight and thermal expansion coefficients of air at temperatures ranging -100 to 1600 °C (-140 to 2900 °F) at atmospheric and higher pressure - Imperial and SI Units.
Diffusion coefficients (D12) for gases in large excess of air at temperatures ranging 0 - 400 °C.
Online calculator, figures and tables with dynamic (absolute) and kinematic viscosity for air at temperatures ranging -100 to 1600°C (-150 to 2900°F) and at pressures ranging 1 to 10 000 bara (14.5 - 145000 psia) - SI and Imperial Units.
Prandtl number for air vs. temperature and pressure.
Properties of air change along the boiling and condensation curves (temperature and pressure between triple point and critical point conditions). An air phase diagram included.
Figures and tables with isobaric (Cp) and isochoric (Cv) specific heat of air at constant temperature and pressure ranging 0.01 to 10000 bara.
Online calculator with figures and tables showing air thermal conductivity vs. temperature and pressure. SI and imperial units.
Figures and tables withdry air thermal diffusivity vs. temperarure and pressure. SI and Imperial units.
Impurities from the feedwater will concentrate in the boiling water.
Make-up water to steam boilers should be treated with oxygen scavengers to avoid serious corrosion problems.
Online calculator, figures and tables showing density and specific weight of oxygen, O2, at varying temperature and pressure - Imperial and SI Units.
Online calculator, figures and tables showing dynamic and kinematic viscosity of oxygen, O2, at varying temperature and pressure - Imperial and SI Units.
Solubility of oxygen in equilibration with air in fresh water and seawater (salt water) - pressures ranging 1 - 4 bar abs.
Chemical, Physical and Thermal Properties of Oxygen - O2.
Specific heat of Oxygen Gas - O2 - at temperatures ranging 175 - 6000 K.
Add standard and customized parametric components - like flange beams, lumbers, piping, stairs and more - to your Sketchup model with the Engineering ToolBox - SketchUp Extension - enabled for use with the amazing, fun and free SketchUp Make and SketchUp Pro . Add the Engineering ToolBox extension to your SketchUp from the Sketchup Extension Warehouse!
We don't collect information from our users. Only emails and answers are saved in our archive. Cookies are only used in the browser to improve user experience.
Some of our calculators and applications let you save application data to your local computer. These applications will - due to browser restrictions - send data between your browser and our server. We don't save this data.