Two methods for determination of oxygen content of high purity sulfur hexafluoride:

　　One,determination of the reason

　　The oxygen content must be kept low to avoid harmful acidic products.Oxygen may be accidentally introduced into the pump when the air is discharged during the maintenance process,or it may remain in the equipment due to faulty maintenance procedures.Therefore,the determination of the oxygen content of high-purity sulfur hexafluoride in the equipment is necessary.

　　High purity sulfur hexafluoride oxygen content has two determination methods:field determination available portable oxygen analyzer,it is the determination of magnetic susceptibility,laboratory determination can be used gas chromatograph.

　　Two,magnetic susceptibility

　　This approach is based on the fact that oxygen is one of the few highly paramagnetic gases.Other strong paramagnetic gases are nitrogen oxide and nitrogen peroxide.All other gases are weakly diamagnetic.

　　There are two types of instruments using this principle,namely,suspended rotation and magnetic wind ty-pe.Either type can be used as long as it can detect high-purity sulfur hexafluoride.The lower limit of oxygen I in gases is 255ppm(weight)or 100ppm(volume).

　　Three,gas chromatography

　　If for some reason(i.e.,higher sensitivity,faster response of the device)gas chromatography is required,for this purpose,the sulfur hexafluoride sample from Dawn should be taken to the laboratory.Feasible analytical methods are described in IEC publication 376"New sulfur hexafluoride Specification and Acceptance".The column must be packed with a column capable of separating oxygen and nitrogen.