可燃气体和混合气极限氧浓度实验研究

Experimental research on the limiting oxygen concentration of gases and gas mixtures

介绍可燃气体极限氧浓度测定的标准及要求,给出可燃气体极限氧浓度的测定原理、测定装置和测定方法。测定方法主要分为管式法和球式法两种,分别采用火焰传播距离(≥100mm)和爆炸起始压力增量指标(5%或7%)判定爆炸现象。4次重复测定爆炸性混合气体的LAC,计算确定待测可燃气体的LOC。采用20L球爆炸实验装置分别测定纯物质丙烷(C3H8)和混合气液化石油气(LPG)的爆炸极限和极限氧浓度,结果表明:混合气的最大爆炸压力随着氧浓度的降低而降低,二者爆炸极限分别为2.0%~9.5%、3.0%~8.0%,用二氧化碳惰化的极限氧浓度分别为13.8%、15.46%。

The test method for limiting oxygen concentration for gases and vapors （LOC） were described, and the test principle, test apparatus and test procedure were introduced. The test methods are divided into tube method and bomb method. The explosion criterion of tube method is flame detachment and propagation of 100 mm at least and pressure rise of 5% or 7% at least of initial pressure for bomb method; The LAC of explo- sive gas mixture was measured 4 times to calculate the LOC of gas to be tested. The 20 L chamber was used to experimental study the limiting oxygen concentration and flammability limits of gas （C3 H8 ） and gas mixtures （LPG）. The results showed that the maximum explosion strength decreased with the de- crease of volume fraction of oxygen in the mixture. Described by the volume fraction in air, the flammability limits of C3 H8 and LPG is from 2.0% to 9.5%, from 3.0% to 8.0%, respec- tively, and the limiting oxygen concentration of C3 H8 and LPG with inerting gas of CO2 is 13.8% and 15.46% respectively.