Flame extinguishment, methods

Soldaini and Bert e s method. 20 c.c. of the oil and a few scraps of pumice are placed in a three-bulbed distillation flask (see p. 278) holding about 70-75 c.c., the flask being connected with a small condenser and closed with a cork traversed by a thermometer. Around the flask—which should rest on an asbestos-gauze—is placed an asbestos card sleeve, which surrounds it at a distance of about 1 cm. and reaches almost to the lowest bulb of the neck. To the free end of the condenser is fitted a graduated cylinder. The oil is then boiled at the ordinary pressure so that one drop falls into the cylinder about every two seconds. When the distillate in the cylinder amounts to one-half the amount of oil taken, i.e. 10 c.c., the cylinder is replaced by an ordinary test-tube and the flame extinguished. The few drops of subsequent distillate are returned to the residue in the distillation flask. 

Samples to be examined by inductively coupled plasma and mass spectrometry (ICP/MS) are commonly in the form of a solution that is transported into the plasma flame. The thermal mass of the flame is small, and ingress of excessive quantities of extraneous matter, such as solvent, would cool the flame and might even extinguish it. Even cooling the flame reduces its ionization efficiency, with concomitant effects on the accuracy and detection limits of the ICP/MS method. Consequently, it is necessary to remove as much solvent as possible which can be done by evaporation off-line or done on-line by spraying the solution as an aerosol into the plasma flame. 

The Standard for Tests for Flammability of Plastic Materials for Parts in Devices and Appliances (UL 94) has methods for determining whether a material will extinguish, or burn and propagate flame. The UL Standard for Polymeric Materials-ShortTerm Property Evaluations is a series of small-scale tests used as a basis for comparing the mechanical, electrical, thermal, and resistance-to-ignition characteristics of materials. 

The above flame retardants, HMPN and TMP, along with another commercially available alkyl phosphate, triethyl phosphate (TEP), were systematically characterized by Xu et al. To quantify the flammability of the electrolytes so that the effectiveness of these flame retardants could be compared on a more reliable basis, these authors modified a standard test UL 94 HB, intended for solid polymer samples, and measured the self-extinguishing time (SET) instead of the universally used flame propagation rate. Compared with the UL 94 HB, this new quantity is more appropriate for the evaluation of the electrolytes of low flammability, since the electrolytes that are determined to be retarded or nonflammable by this method all showed zero flame propa-... 

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