Static ignition hazard control

Mancini, R.A., The use (and misuse) of bonding for control of static ignition hazards, Plant/Operations Progress, 7, No. 1, January 1988. 

Static charge generation causes an ignition hazard only if the accumulated charges create an electric field sufficient to produce an electrical discharge in a flammable atmosphere. In most processes, this means that the electric field intensity at some location must reach the breakdown strength of air (nominally 3 X lO " V/m). The objective of static-control measures is to ensure that electric field intensities cannot reach this value. 

Filtration of oxidizable materials can constitute a serious fire hazard. The ignition source can be a burning particle from the dryer or the static charge carried by the dust particle. Because of this, bag-house systems should be equipped with automatic devices for closing off the airflow in case of fire, should be provided with adequate sprinklers or chemical fire control apparatus, and vents should be provided on the side containing the dust particles. 

When faced with the potential for spontaneous ignition of hazardous vapors and dusts, controlling static electricity is critical. 

Static electricity is a workplace hazard because of its potential to ignite (by arc) certain vapor or dust mixtures in air. Various controls are available to minimize the effects of static charges, dependent on the individual case ... 

The source of ignition can be an open flame, a spark, a hot surface, static electricity, or autoignition. Plant personnel must strive to eliminate all ignition sources from locations where flammable materials are stored or handled or must institute procedtues to control the resulting hazards. 

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