Propyne
- C3H4
- CAS Number 74-99-7
- UN1954 (gas)
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Liquid / Gas Volumes
Calculate the volume or mass of a quantity of gas or liquid
Liquid Phase
At boiling point at 1.013 bar
Gas Phase
In standard conditions (1.013 bar, 15°C)
Physical Properties
Molecule phase diagram showing the transition phases between solid, liquid and gas as a function of temperature and pressure
-
- Molar mass 40.060 g/mol
- Content in dry air /
-
Critical Point
- Temperature 129.25 °C
- Pressure 56.3 bar
- Density 244.29 kg/m³
-
Triple Point
- Temperature -102.65 °C
- Pressure 4.171E-3 bar
Pressure 1.013 bar
| Latent heat of fusion (at melting point) | 133.55 kJ/kg |
| Melting point | - 102.7 °C |
Pressure 1.013 bar
| Boiling point | - 25.15 °C |
| Latent heat of vaporization (at boiling point) | 553.731 kJ/kg |
| Liquid density (at boiling point) | 671.963 kg/m3 |
| Compressibility factor Z | 9.7675E-1 |
| Cp/Cv ratio γ | 1.1865 |
| Gas density | 1.8299 kg/m3 |
| Gas/(liquid at boiling point) equivalent | 367.313 vol/vol |
| Heat capacity Cp | 1.4958 kJ/(kg.K) |
| Heat capacity Cv | 1.2607 kJ/(kg.K) |
| Specific volume | 5.465E-1 m3/kg |
| Thermal conductivity | 13.725 mW/(m.K) |
| Viscosity | 7.9079E-5 Po |
| Compressibility factor Z | 9.8092E-1 |
| Cp/Cv ratio γ | 1.1761 |
| Gas density | 1.7272 kg/m3 |
| Gas/(liquid at boiling point) equivalent | 390.449 vol/vol |
| Heat capacity Cp | 1.5275 kJ/(kg.K) |
| Heat capacity Cv | 1.2988 kJ/(kg.K) |
| Specific volume | 5.79E-1 m3/kg |
| Thermal conductivity | 15.19 mW/(m.K) |
| Viscosity | 8.3459E-5 Po |
| Compressibility factor Z | 9.8311E-1 |
| Cp/Cv ratio γ | 1.1702 |
| Gas density | 1.6656 kg/m3 |
| Gas/(liquid at boiling point) equivalent | 404.889 vol/vol |
| Heat capacity Cp | 1.5512 kJ/(kg.K) |
| Heat capacity Cv | 1.3256 kJ/(kg.K) |
| Specific volume | 6.004E-1 m3/kg |
| Thermal conductivity | 16.188 mW/(m.K) |
| Viscosity | 8.6348E-5 Po |
Applications
Examples of uses of this molecule in Industry and Healthcare
Safety & Compatibility
GHS02
Flammable
GHS04
Gas under pressure
Autoignition Temperature, Flammability Limits & Flash Point
Europe (according to EN1839 for Limits and EN 14522 for autoignition temperature)
| Autoignition temperature (Chemsafe) | 340 °C |
| Lower flammability limit (IEC 80079-20-1) | 1.8 vol% |
| Upper flammability limit (IEC 80079-20-1) | 16.8 vol% |
US (according to ASTM E681 for Limits and ASTM E659 for autoignition temperature)
| Lower flammability limit (NFPA 325) | 1.7 vol% |
Threshold of toxicity
| PEL USA OSHA (vol) | 1000 ppm |
| VLEP 8h France (at Patm and 293.15 K) | 1650 mg/m3 or 1000 ppm |
Odor
Sweet
Metals
| Aluminium | Satisfactory |
| Brass | Satisfactory |
| Monel | No data |
| Copper | No data |
| Ferritic Steel | Satisfactory |
| Stainless steel | Satisfactory |
| Zinc | No data |
| Titanium | No data |
Plastics
| Polytetrafluoroethylene | Satisfactory |
| Polychlorotrifluoroethylene | Satisfactory |
| Polyvinylidene fluoride | Satisfactory |
| Polyvinyl chloride | Satisfactory |
| Ethylene tetrafluoroethylene | No data |
| Polycarbonate | No data |
| Polyamide |
Significant loss of mass
Acceptable
|
| Polypropylene | Satisfactory |
Elastomers
| Butyl (isobutene- isoprene) rubber | No data |
| Nitrile rubber | No data |
| Chloroprene | No data |
| Chlorofluorocarbons | No data |
| Silicone | No data |
| Perfluoroelastomers | No data |
| Fluoroelastomers | No data |
| Neoprene | No data |
| Polyurethane | No data |
| Ethylene-Propylene | No data |
Lubricants
| Hydrocarbon based lubricant |
Significant loss of mass and impurities in the gas
Not recommended
|
| Fluorocarbon based lubricant | Satisfactory |
Materials compatibility
Recommendations : Air Liquide has gathered data on the compatibility of gases with materials to assist you in evaluating which materials to use for a gas system. Although the information has been compiled from what Air Liquide believes are reliable sources (International Standards: Compatibility of cylinder and valve materials with gas content; Part 1- Metallic materials: ISO11114-1 (March 2012), Part 2 - Non-metallic materials: ISO11114-2 (April 2013), it must be used with extreme caution and engineering judgement. No raw data such as these can cover all conditions of concentration, temperature, humidity, impurities and aeration. It is therefore recommended that this table is only used to identify possible materials for applications at high pressure and ambient temperature. Extensive investigation and testing under the specific conditions of use need to be carried out to validate a material selection for a given application. Contact the regional Air Liquide team for expertise service.
Learn More
More information
Propyne, or methylacetylene, is an alkyne with the chemical formula CH3C≡CH. It is produced as a side product, often an undesirable one, by cracking propane to produce propene, an important feedstock in the chemical. European space companies have researched using light hydrocarbons with liquid oxygen as a relatively high performing liquid rocket propellant combination that would also be less toxic than the commonly used MMH/NTO (monomethylhydrazine/nitrogen tetroxide). Their research showed that propyne would be highly advantageous as a rocket fuel for craft intended for low Earth orbital operations. It is colorless and highly flammable.