Standard Test Method for Temperature Limit of Flammability of Chemicals

Importancia y uso:

5.1 The lower temperature limit of flammability is the minimum temperature at which a liquid (or solid) chemical will evolve sufficient vapors to form a flammable mixture with air under equilibrium conditions. Knowledge of this temperature is important in determining guidelines for the safe handling of chemicals, particularly in closed process and storage vessels.

Note 1: As a result of physical factors inherent in flash point apparatus and procedures, closed-cup flash point temperatures are not necessarily the minimum temperature at which a chemical will evolve flammable vapors (see Appendix X2 and Appendix X3, taken in part from Test Method E502). The temperature limit of flammability test is designed to supplement limitations inherent in flash point tests (Appendix X2). It yields a result closely approaching the minimum temperature of flammable vapor formation for equilibrium situations in the chemical processing industry such as in closed process and storage vessels.

Note 2: As a result of flame quenching effects existing when testing in standard closed-cup flash point apparatus, there are certain chemicals that exhibit no flash point but do evolve vapors that will propagate a flame in vessels of adequate size (X3.2). The temperature limit of flammability test chamber is sufficiently large to overcome flame quenching effects in most cases of practical importance, thus, usually indicating the presence of vapor-phase flammability if it does exist (6.2).

Note 3: The lower temperature limit of flammability (LTL) is only one of several characteristics that should be evaluated to determine the safety of a specific material for a specific application. For example, some materials are found to have an LTL by this test method when, in fact, other characteristics such as minimum ignition energy and heat of combustion should also be considered in an overall flammability evaluation.

5.2 The vapor concentration present at the lower temperature limit of flammability equals the lower flammable limit concentration as measured by Test Method E681 and extrapolated back to the same temperature. (This permits estimation of lower temperature limits of flammability if vapor pressure and concentration limit of flammability data are available (A2.3). A comparison of results of the tests, thus, affords a check on test reliability, the reliability of vapor pressure data, or both.)

Subcomité:

E27.04

Referida por:

E0502-21A, E1445-08R23

Volúmen:

14.01

Número ICS:

13.220.40 (Ignitability and burning behaviour of materials and products), 71.100.01 (Products of the chemical industry in general)