# Gas density

The sources are:

• Values for 0, 15, and 25°C are taken from encyclopedia.airliquide.com
• Values for 50, 75, and 100°C are taken from nist.gov
• Values for 50, 75, and 100°C for dry air have been calculated using the equation from Dumas & Trancossi, 2009.
• Equation for humid air is taken from paper by P.T. Tsilingiris: 'Thermophysical and transport properties of humid air at temperature range between 0 and 100°C', 2007
• Equation for air is taken from paper by A. Dumas and M. Trancossi: 'Design of Exchangers Based on Heat Pipes for Hot Exhaust Thermal Flux, with the Capability of Thermal Shocks Absorption and Low Level Energy Recovery', 2009
• Equation for humid air is taken from paper by P.T. Tsilingiris: 'Thermophysical and transport properties of humid air at temperature range between 0 and 100°C', 2007
• Equation for air is taken from paper by A. Dumas and M. Trancossi: 'Design of Exchangers Based on Heat Pipes for Hot Exhaust Thermal Flux, with the Capability of Thermal Shocks Absorption and Low Level Energy Recovery', 2009. They are calculated from polynomial curve fits to a data set for 100 K to 1600 K in the SFPE Handbook of Fire Protection Engineering, 2nd Edition Table B-2. You may find a free air property calculator from Pierre Bouteloup
• Equations for N2 and SF6 are taken from paper by J. Vermeer: 'A simple formula for the calculation of the convective heat transfer between conductor and sheath in compressed gas insulated (CGI) cables', 1983 as published in Elektra 87
• The factor 353.0 in the formula for Air was calculated by multiplying $1.1840\cdot(273.15+25)$.
• The factor 538.9 in the formula for CO2 was calculated by multiplying $1.8075\cdot(273.15+25)$.
• The factor 390.1 in the formula for O2 was calculated by multiplying $1.3085\cdot(273.15+25)$.

Symbol
$\rho_{gas}$
Unit
kg/m$^3$
Formulae
 $1.293393662-5.538444326{\cdot}{10}^{-3} \theta_{gas}+3.860201577{\cdot}{10}^{-5} {\theta_{gas}}^2-5.2536065{\cdot}{10}^{-7} {\theta_{gas}}^3$ humid air @ 1 atm (Tsilingiris2007) $360.77819{T_{gas}}^{-1.00336}$ air @ 1 bar (Dumas&Trancossi2009) $\frac{351.99}{T_{gas}}+\frac{344.84}{{T_{gas}}^2}$ air @ 1 bar (UW/MHTL 8406, 1984) $\frac{353p_{gas}}{T_{gas}}$ air (ideal gas) $\frac{337.4p_{gas}}{T_{gas}}$ N2 (Vermeer1983) $\frac{1666p_{gas}}{230+\theta_{gas}}$ SF6 (Vermeer1983) $\frac{538.9p_{gas}}{\theta_{gas}+\theta_{abs}}$ CO2 (linear interpolation) $\frac{\frac{1}{R_{gas}} p_{gas}}{T_{gas}}$ ideal gas $\frac{390.1p_{gas}}{\theta_{gas}+\theta_{abs}}$ O2 (linear interpolation)
Related
$p_{gas}$
$R_{gas}$
$T_{gas}$
$\theta_{abs}$
$\theta_{gas}$
Used in
$\alpha_{gas}$
$\eta_{gas}$
$\nu_{gas}$
$p_{gas}$
$T_{conv,ce}$
$W_{a,L}$
Choices
GasFormula0°C15°C25°C50°C75°C100°C
Air78%N2+21%O2+minor1.2921.2251.1841.09341.01430.9462
N2N21.25011.18481.1451.05620.98020.9145
SF6SF66.61616.25636.03835.55545.14664.7949
CO2CO21.97631.87141.80751.66571.54481.4403
COCO1.25021.18491.1451.05620.98020.9144
O2O21.42871.3541.30851.2071.12011.0449
H2H20.08990.08520.08230.0760.07050.0658
NH3NH30.77130.72890.70330.64710.59950.5586
SO2SO22.93052.76332.66362.44592.26342.1073
HeHe0.17840.16920.16350.15090.140.1306
ArAr1.78351.69031.63351.50681.39831.3045
KrKr3.7483.55143.43143.16442.93612.7386
XeXe5.89655.5845.39374.97074.60994.2983
NeNe0.89960.85280.82420.76050.70590.6586