|Committee on Hazard Potential of Chemicals Developing Low Phi-Factor Calorimetry Standard
ASTM International Committee E27 on Hazard Potential of Chemicals has begun to develop a new proposed standard on assessing the thermal stability of materials by methods of low phi-factor calorimetry. The proposed standard, which is under the jurisdiction of Subcommittee E27.02 on Thermal Stability and Condensed Phases, has been given the work item number WK6139.
The phi factor is the ratio of the total heat capacity of a test system to the heat capacity of a test sample. The proposed guide will cover suggested procedures for the operation of low phi-factor calorimetric devices designed to obtain temperature and pressure data as a function of time.
In low-phi factor tests, less of the generated heat is adsorbed by the test cell as opposed to tests that utilize a heavy-walled (higher phi-factor) test cell, says Jeff Niemeier, an engineering consultant at Eli Lilly and Co. Therefore, this type of calorimetry testing allows more accurate determination of heat and gas generation rates that could occur in the plant setting where the phi factor is generally low.
According to Niemeier, the new standard will be useful because it will provide a user with a better understanding of the parameters that must be considered when designing an experiment with low-phi factor instruments. These parameters include selection of type of test (open versus closed), method of addition of reactants, pre-test pressure checks, and selection of stirring level. Having knowledge of these parameters will aid the users ability to obtain useful information from an experiment. The standard will also provide advice on data interpretation and application.
Subcommittee E27.02 is seeking participation in the development of this standard from users and manufacturers of low phi-factor instruments. //
Jeff Niemeier, Eli Lilly and Co., Indianapolis, Ind.
April 19-21, April 2005 Committee Week, Reno, Nev.