Abstract
Two methods are described for assessing the ability of electrostatic
discharges from an isolated, charged textile to ignite a hydrogen-air
mixture. One used a continuous gas flow, the other a fixed volume
of gas. In the flowing-gas technique, frequency of ignition for some
textiles seemed to show a sigmoidal dependence on the initial surface
charge density, sigmasurf. The threshold value of sigmasurf for
ignition is a characteristic of the textile involved, but shows a
relatively weak dependence on surface resistivity. Other textiles
appear to show maxima in their ignition probability versus sigmasurf
relationships, while for others, no clear correlation between ignition
probability and sigmasurf could be detected. A good correlation
was found between the `minimum surface charge density for ignition'
parameter using the flowing-gas technique, and the `frequency of
ignition' parameter using the fixed-volume technique. We found that
under the conditions described, textiles with conductive threads
did not give ignitions provided they were adequately earthed. When
isolated, all textiles were capable of causing ignitions regardless
of the anti-static strategy employed.
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