| 摘要 |
PURPOSE:To measure the amount of particles in a liquefied gas correctly by promptly evaporating the liquefied gas which is kept sufficiently cold, heating the vaporized gas again and measuring the amount of particles therein. CONSTITUTION:A liquefied gas to be measured, for example, liquefied N2 gas is kept in the sufficiently cooled state by a liquefied gas of the same kind as the to-be-measured gas in a vacuum double pipe of heat insulating material so as not to turn to vapor until it enters an evaporator. When the liquefied gas is to be instantly vaporized in the evaporator, it is preferable to use an oil bath or a water bath as a heat medium. Then, the vaporized gas is heated again to approximately 100 deg.C or higher, more preferably, approximately 200 deg.C or higher to vaporize the ice in the liquefied gas. The particles in the vaporized gas are measured by a laser particle counter. According to this method, it becomes possible to measure the amount of particles in a liquefied gas other than liquefied N2 gas, for instance air, Ar, CO2, He, H2, Ne, O2 or the like. |
