Introduction

Prevention of unwanted fires and gas explosion disasters requires a knowledge of flammability characteristics (limits of flammability, ignition requirements, and burning rates) of pertinent combustible gases and vapors likely to be encountered under various conditions of use (or misuse). Available data may not always be adequate for use in a particular application since they may have been obtained at a lower temperature and pressure than is encountered in practice. For example, the quantity of air that is required to decrease the combustible vapor concentration to a safe level in a particular process carried out at 200°C should be based on flammability data obtained at this temperature. When these are not available, suitable approximations can be made to permit a realistic evaluation of the hazards associated with the process being considered; such approximations can serve as the basis for designing suitable safety devices for the protection of personnel and equipment.

The purpose of this bulletin is to present a general review of the subject of flammability, and to supply select experimental data and empirical rules on the flammability characteristics of various families of combustible gases and vapors in air and other oxidizing atmospheres. It contains what are believed to be the latest and most reliable data for more than 200 combustibles of interest to those concerned with the prevention of disastrous gas explosions. In addition, the empirical rules and graphs presented here can be used to predict similar data for other combustibles under a variety of conditions. This bulletin supplements Bureau bulletins (40)^N and other publications (158).

Basic knowledge of combustion is desirable for a thorough understanding of the material, which can be found in numerous publications (69, 199, 202). Therefore, only those aspects required for an understanding of flammability are considered here; even these are considered from a fairly elementary viewpoint.