In the liquid oxygen, in addition to acetylene (C2H2), there are also methane (municipality), acetane (C2H6), Propylene (C3H8), ethylene (C2H4), Propylene (C3H4) and other hydrocarbon. These substances are combustible substances. Sometimes, although the content of acetylene does not exceed the standard, if the content of hydrocarbon is too high, there is also the risk of explosion. Therefore, the total amount of these hydrocarbon is required to be controlled within the allowable range. Generally, the total carbon content per liter of liquid oxygen is required to be within 30 mg/L.
There are many hydrocarbon components in liquid oxygen, but methane accounts for about 80% ~ 90%, therefore, the method to determine the total content of hydrocarbon is to determine the content of methane after they are hydrofined to methane under the effect of catalyst. When the volume fraction of methane in liquid oxygen is 1 × 10-6, that is, the content of methane is 0.8 mL/L, or 0.8 × 16/22. 4 = 0.57 mg/L. Because the relative molecular mass of methane is 16, in which carbon accounts for 0.75, the carbon content is 0.57 × 0.75 = 0.428 mg/L. If the total carbon content in liquid oxygen is to be controlled below 30 mg/L, the content of methane should be controlled at 30/0. 75 = 40 mg/L = less than 50 mL/L, that is, the volume fraction is less than 50 × 22.4 × 10-6/16 = 70 × 10-6.
