Method and apparatus for predicting the explosiveness of a volume containing inert gas and hydrocarbon vapors when mixed with air

摘要

A method is disclosed for changing the inert gaseous content of a volume including hydrocarbon vapors to air without producing an explosive mixture. First a sample is obtained from the volume and then mixed with air to form a gas mixture. During the mixing, the mixture is monitored for values including percentage in tenths of lower explosive limit and percentage of oxygen. Then the values are evaluated to see if the mixture forms an explosive mixture; and, if so, the volume is purged with an inert gas prior to ventilating the volume with air to remove the inert gaseous content including hydrocarbon vapors from the volume without producing an explosive mixture of the hydrocarbon vapors and air. P PApparatus is also disclosed for use with the method. A sampling hose is located in a gaseous sample volume of inert gas and hydrocarbon vapors. It is connected to a valve to regulate the flow of gas through it. A second valve is connected to a source of air. These valves are also connected to respective sides of a tee so that the sample volume and air begin to mix in it as the mixture passes to a catalytic combustion indicator. The indicator reads percent oxygen and the percent (as a decimal) of the lower explosive limit.PPThe results may be recorded graphically or may be displayed on digital means by using two analog-to-digital converters, a summer and a digital display. One converter emits a unit pulse series for each tenth of the lower explosive limit; the other emits a unit pulse series for each percent of oxygen. These pulses are added in the summer and displayed on a digital display.