Flash point
The flash point of a material is the "lowest liquid temperature at which, under certain standardized conditions, a liquid gives off vapours in a quantity such as to be capable of forming an ignitable vapour/air mixture". (EN 60079-10-1)
The flash point is sometimes confused with the
Fuels
The flash point is a descriptive characteristic that is used to distinguish between
.It is also used to characterize the fire hazards of fuels. Fuels which have a flash point less than 37.8 °C (100.0 °F) are called flammable, whereas fuels having a flash point above that temperature are called combustible.[2]
Mechanism
All
Measurement
There are two basic types of flash point measurement: open cup and closed cup.
There are two types of closed cup testers: non-equilibrial, such as Pensky-Martens, where the vapours above the liquid are not in temperature equilibrium with the liquid, and equilibrial, such as Small Scale (commonly known as Setaflash), where the vapours are deemed to be in temperature equilibrium with the liquid. In both these types, the cups are sealed with a lid through which the ignition source can be introduced. Closed cup testers normally give lower values for the flash point than open cup (typically 5–10 °C or 9–18 °F lower) and are a better approximation to the temperature at which the vapour pressure reaches the
The flash point is an empirical measurement rather than a fundamental physical parameter. The measured value will vary with equipment and test protocol variations, including temperature ramp rate (in automated testers), time allowed for the sample to equilibrate, sample volume and whether the sample is stirred.
Methods for determining the flash point of a liquid are specified in many standards. For example, testing by the
CEN/TR 15138 Guide to Flash Point Testing and ISO TR 29662 Guidance for Flash Point Testing cover the key aspects of flash point testing.
Examples
Fuel | Flash point | Autoignition temperature |
---|---|---|
Ethanol (70%) | 16.6 °C (61.9 °F)[5] | 363 °C (685 °F)[5] |
Coleman fuel (White Gas) | −4 °C (25 °F)[6] | 215 °C (419 °F)[6] |
Petrol (gasoline)
|
−43 °C (−45 °F)[7] | 280 °C (536 °F)[8] |
Diesel (2-D) | >52 °C (126 °F)[7] | 210 °C (410 °F)[8] |
Jet fuel (A/A-1) | >38 °C (100 °F) | 210 °C (410 °F) |
Kerosene | >38 °C (100 °F)[9] | 210 °C (410 °F)[9] |
Vegetable oil (canola) | 327 °C (621 °F) | 424 °C (795 °F)[10] |
Biodiesel | >130 °C (266 °F) |
Jet fuel flash points also vary with the composition of the fuel. Both Jet A and Jet A-1 have flash points between 38 and 66 °C (100 and 151 °F), close to that of off-the-shelf kerosene. Yet both Jet B and JP-4 have flash points between −23 and −1 °C (−9 and 30 °F).
Standardization
Flash points of substances are measured according to standard test methods described and defined in a 1938 publication by T.L. Ainsley of South Shields entitled "Sea Transport of Petroleum" (Capt. P. Jansen). The test methodology defines the apparatus required to carry out the measurement, key test parameters, the procedure for the operator or automated apparatus to follow, and the precision of the test method. Standard test methods are written and controlled by a number of national and international committees and organizations. The three main bodies are the CEN / ISO Joint Working Group on Flash Point (JWG-FP), ASTM D02.8B Flammability Section and the Energy Institute's TMS SC-B-4 Flammability Panel.
See also
References
- ^ Sea Transport of Petroleum, Jansen and Hayes, Ainsley, South Shields 1938
- ^ "Use and Storage of Flammable & Combustible Liquids | Environmental Health and Safety | Iowa State University". www.ehs.iastate.edu. Retrieved 2021-11-10.
- ^ Jansen and Hyams.pp62
- ^ "Standard Test Method for Flash and Fire Points by Cleveland Open Cup Tester", ASTM.org
- ^ a b "Ethanol MSDS" (PDF). Nafaa.org. Archived from the original (PDF) on June 17, 2019. Retrieved January 4, 2014.
- ^ a b "Coleman Fuel MSDS" (PDF). farnell.com/. Retrieved November 3, 2019.
- ^ a b "Flash Point — Fuels". Engineeringtoolbox.com. Retrieved January 4, 2014.
- ^ a b "Fuels and Chemicals — Autoignition Temperatures". Engineeringtoolbox.com. Retrieved January 4, 2014.
- ^ a b "Flammability - an overview | ScienceDirect Topics". www.sciencedirect.com.
- ^ Buda-Ortins, Krystyna. "Auto-Ignition of Cooking Oils" (PDF). Drum.lib.umd.edu.