Flash point determination

Flammability—Flash Point The closed-cup flash point determination produces the most important data to determine the potential for fire. The flash point is the lowest temperature at which the vapors can be ignited under conditions defined by the test apparatus and method. 

Flash point determinations may be made in elosed or open eontainers, giving different values ... 

Safety tests. See also Flash point determination, 459 Salts, 32, 56... 

Figure 6-3 Cleveland open-cup flash point determination. The test flame applicator is moved back and forth horizontally over the liquid sample.

Apply this correction to all flash point determinations between 0 and 60F (—17.8 to 15.6C). Round off corrections to the nearest whole number according to Recommended Practice E 29... 

From the point of view of the potential for a fire, the closed cup flash point determination is usually the most important. In a perfect closed cup test, the vapor pressure is in equilibrium with the liquid at the temperature of the test. At the flash point, the vapor composition is at the lower flammable limit. In fact, the lower flammable limit can be estimated from vapor pressure data (for a pure compound). Open cup flash points are generally higher and, thus less conservative, than closed cup determinations. The value determined in an open cup test is subject to air movement at the open face of the cup and true vapor-liquid equilibrium probably does not occur. 

Flash-points determined in an oxygen atmosphere are appreciably lower than in air. 

Flash Point. Determine it in accordance with method 1103.7 of Federal Test Method... 

Flash points calculated by the proposed sum-of-indexes method are compared in Table III with experimentally determined flash points. To place this comparison in context, Table III also includes several other comparisons between sets of data. When earlier experimentally determined data were compared with flash points redetermined for this study, the differences were almost evenly distributed around the zero point. The median absolute difference between the two sets of data was 5°F while the largest difference between flash points determined for a single blend was 27°F. Some skew is apparent in the differences between either set of experimental data and the calculated flash points. The median absolute differences between experimental and calculated data were either 7° or 8°F depending upon which set of experimental data was used in the comparison. When the flash point of the lowest flashing component was taken as an indication of blend flash point, the median differences from the two sets of experimental data were 13° and 18 °F, respectively. 

For the two sets of experimental data, the 95% confidence limits for differences between flash point determinations were +3.2° to —3.2 °F. 

Table 3-7 Overview on relevant standards for flash-point determination methods...

Flash point determinations on mixtures of xylene with polar solvents led to the following conclusions [14.91], [14.92] ... 

The flash point is not the temperature at which the vapor pressure in air equals the lower flammable limit. Although both parameters have some correspondence there are large differenees between groups of solvents. There is a general tendency for solvents with a lower flammability limit to have a lower flash point. The flash point determination uses a... 

Fig. 3.14 Closed cups for flash point determination a Abel s closed cup b Pensky-Martens closed cup c Tag s closed cup. Dimensions in mm...

Flash point (1878). n The lowest temperature at which a combustible liquid will give off a flammable vapor that will momentarily burn when exposed to s small flame. The flash point can be determined by the open cup or the closed cup method. The flash point determined by the open cut method is usually somewhat higher than the closed cup method. Wray HA (ed) (1991) Manual for flash point standards and their use. American Society for Testing and Materials, Philadelphia, PA. 

On the basis of the flash points determined in a closed cup and under consideration of the boiling point flammable liquids are classified according to their hazard qualities. 

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