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Propane - Thermophysical properties

Chemical, physical and thermal properties of propane gas - C3H8.

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Phase diagram of propane

Chemical, physical and thermal properties of Propane - C3H8:
(values at 25oC (77oF, 298 K) and atmospheric pressure)

Propane - Thermophysical properties
Molecular Weight 44.097
Specific Gravity of gas (air = 1) 1.52
Specific Volume (ft3/lb, m3/kg) 8.84, 0.552
Density of liquid at atmospheric pressure (lb/ft3, kg/m3) 36.2, 580
Vapor pressure at 25oC (psia, MN/m2) 135.7, 0.936
Absolute Viscosity (lbm/ft s, centipoises) 5.38 10-6, 0.0074
Sound velocity in gas (m/s) 253
Specific Heat - cp - (Btu/lboF or cal/goC, J/kgK) 0.39, 1630
Specific Heat Ratio - cp/cv 1.13
Gas constant - R - (ft lb/lboR, J/kgoC) 35.0, 188
Thermal Conductivity (Btu/hr ft oF, W/moC) 0.010, 0.017
Boiling Point - saturation pressure 14.7 psia and 760 mm Hg - (oF, oC) -44, -42.2
Latent Heat of Evaporation at boiling point (Btu/lb, J/kg) 184, 428000
Freezing or Melting Point  at 1 atm (oF, oC) -309.8, -189.9
Latent Heat of Fusion (Btu/lb, J/kg) 19.1, 44400
Critical Temperature (oF, oC) 205, 96
Critical Pressure (psia, MN/m2) 618, 4.26
Critical Volume (ft3/lb, m3/kg) 0.073, 0.0045
Flammable yes
Heat of combustion (Btu/ft3, Btu/lb, kJ/kg) 2450, 21660, 50340

See the following documents for changes in propane properties with changes in pressure and temperature:

See also more about atmospheric pressure, and STP - Standard Temperature and Pressure & NTP - Normal Temperature and Pressure,
as well as Thermophysical properties of: Acetone, Acetylene, Air, Ammonia, Argon, Benzene, Butane, Carbon dioxide, Carbon monoxide, Ethane, Ethanol, Ethylene, Helium, Hydrogen, Hydrogen sulfide, Methane, Methanol, Nitrogen, Oxygen, Pentane, Toluene, Water and Heavy water, D2O.

Propane is a gas at standard conditions. However, at low temperature and/or high pressures the gas becomes a liquid (or a solid at very cold conditions).

The phase diagram for propane shows the phase behavior with changes in temperature and pressure. The curve between the critical point and the triple point shows the propane boiling point with changes in pressure. It also shows the saturation pressure with changes in temperature.

Propane phase diagram

At the critical point there is no change of state when pressure is increased or if heat is added.

The triple point of a substance is the temperature and pressure at which the three phases (gas, liquid, and solid) of that substance coexist in thermodynamic equilibrium.

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