Estimation of Flammability Limits of Selected Fluorocarbons with F(sub 2) and CIF(sub3) Page: 64 of 78
This report is part of the collection entitled: Office of Scientific & Technical Information Technical Reports and was provided to Digital Library by the UNT Libraries Government Documents Department.
The following text was automatically extracted from the image on this page using optical character recognition software:
CALIBRATION OF FLAME LIMIT CORRELATIONS
D.1. EXPERIMENTAL DATA USED IN CALIBRATIONS
As indicated in the text, the prediction methods discussed in this report are based on empirical
correlation between computed post-reaction temperatures and experimental information on
ignitability of gas mixtures. Each prediction method developed a threshold temperature which is
a function of flammable gas composition. Both methods need to be calibrated to available
experimental data. The data used for this purpose are listed in this appendix.
Data points were taken from experimental work derived from several sources. Some of those
experiments were explicitly designed to find flammability boundaries, while others more or less
incidentally determined such boundaries in the course of investigating flame behavior well
within the boundary of compositions which could sustain a flame. The experimental data used
consist of the composition of mixtures which would (or would not) burn. Initial temperature and
pressure can have some influence on flammability, and, where stated, it was recorded, although
all initial conditions were near 1 atmosphere and room temperature.
The experimental initial conditions (temperature, pressure, and composition) were provided as
inputs to the appropriate detonation theory model and to ADIAB95/SOLGAS. From these, the
isentropic (i.e., constant volume adiabatic) temperature T~s in the first case, or the constant
pressure adiabatic temperature T, in the second, were computed . These compositions and
computed temperatures are listed in Table D.l. There is frequently a large difference between
the two computed temperatures. This is due primarily to the inclusion of radicals and other low-
temperature unstable species as possible products in the equilibrium model, with a lesser
contribution from the fact that constant volume adiabatic temperatures will generally be
somewhat higher than constant pressure adiabatic temperatures in reactions such as these.
D.2 FLAMMABILITY CORRELATION USED IN DETONATION MODELS
The threshold function used in Barber's 1992 predictions, and which is retained here in the
detonation model spreadsheets is:
Tfhishold = A In (X0d/dXfv.) + B ,
the empirical flammability criterion being that if T, > Tfhthold, the mixture is predicted to be
flammable. Figure D.1 plots Ti,, versus the function (Xoxd;eXfueI) on a semilog plot for all flame
boundary data points in the six systems for which spreadsheets were constructed.
Here’s what’s next.
This report can be searched. Note: Results may vary based on the legibility of text within the document.
Tools / Downloads
Get a copy of this page or view the extracted text.
Citing and Sharing
Basic information for referencing this web page. We also provide extended guidance on usage rights, references, copying or embedding.
Reference the current page of this Report.
Trowbridge, L.D. Estimation of Flammability Limits of Selected Fluorocarbons with F(sub 2) and CIF(sub3), report, September 1, 1999; Tennessee. (https://digital.library.unt.edu/ark:/67531/metadc623234/m1/64/: accessed May 24, 2019), University of North Texas Libraries, Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.