Abstract: Because some needle flame test devices adopt the method of extinguishing the flame at the moment when the flame application time reaches, this method is affected by the electromagnetic valve, which has a serious impact on the test results. In this paper, the causes of the impact are analyzed, the concept of ignition time is put forward, and a sample that can identify the sub-species risk is put forward. The laboratory can use the characteristics of this sample to identify the needle flame test devices with such risks, so as to avoid the testing risks.

Key words: Proficiency testing, Needle flame test, Reference Material, Ignition time, Solenoid valve