Experiment Study On Electrostatic Discharge Ignition Of Aircraft Oxygen Fill Valve Head

During the oxygenation process,polymer oxygen supply valve heads may accumulate static charges and discharge.Under high pressure pure oxygen environment,the combustion characteristics of materials that are nonflammable in air will change,which may lead to fire disasters due to electrostatic discharge.Owing that oxygen is a combustion-supporting gas,once the oxygen system catches fire,serious loss of life and property will be caused.Therefore,in order to control and prevent such accidents,it is necessary to study the electrostatic discharge ignitability of the valve head material under oxygen supplying environment.In this paper,the potential source of electrostatic charge,charge ability and discharge effect during the actual oxygenation process of the oxygen valve head were analyzed firstly.Then,based on the spark discharge method,the minimum ignition energy of the material under MPa level pressure pure oxygen condition was tested.Therefor,the electric spark ignition system and the spark energy test system were designed.The method of integrating the discharge current and voltage of the electrodes was used to replace the traditional method of directly using the energy of the storage capacitor as the spark energy.In order to meet the experimental requirements of high pressure,a safe and reliable high-pressure electrostatic discharge ignition sealing device was developed independently.And an improved method of solid electrodes that discharge along dielectric surface was proposed for the first time.Moreover,the corresponding experimental system and method were established.Nylon 1010,an oxygen supply valve head material used in the event of a fire accident in an aircraft's oxygen system,was subjected to the electrostatic discharge ignition test and ignition energy measurement under high pressure pure oxygen environment.In addition,the risk of the ignition of the valve head by electrostatic discharge was analyzed preliminarily.The main results are as follows:(1)Within the experimental energy range of this paper,the energy loss rate of the storage capacitor is as high as 730-93%.The use of the discharge energy integration method to test the ignition energy effectively improves the accuracy of the experimental results.(2)As the oxygen pressure increases,the minimum ignition energy of nylon 1010 decreases rapidly,the minimum ignition energy drops to 0.55mJ when the pressure is 3MPa,compared to the standard atmospheric pressure is reduced by 1364 times,which has the risk to be ignited by electrostatic discharge.The research results have certain significance to the mechanism analysis,electrostatic protection and related improvement of the fire accident on oxygen systems.