Electrostatic Discharge Ignition in Oxygen

Electrostatic Discharge (ESD) is an ignition mechanism of concern in home healthcare and hospital fires involving elevated oxygen concentrations. However, the ignition conditions and minimum ignition energies of common textiles, including 100% cotton and cotton/polyester fabrics, when subjected to an electrostatic spark discharged from the human body, are not readily established by the technical literature. Further, a test methodology to establish the minimum ESD ignition energy is not available. In order to evaluate the severity of ESD as an ignition mechanism in several low-pressure fires, WHA developed a test system to establish the ignition susceptibility of common textiles when subjected to an electrostatic spark. The test method established is based upon the internationally recognized Electrostatic Discharge (ESD) Human Body Model modified to more closely simulate discharging a spark through a textile. The textiles can be tested in air as well as various oxygen concentrations and ESD energy levels. This test method provides data that is useful in establishing the ignitability of specified textiles subjected to ESD.

The following shows the visual appearance of three sparks, of varying spark energy, discharging through cotton samples.

 

4 mJ 58 mJ 480 mJ
4 mJ 58 mJ 480 mJ