Static electricity charge separation

Sparks due to static electricity associated with the separation of two dissimilar materials (Table 5.5). The charges may be transported/conducted some distance after separation before there is sufficient accumulation to produce a spark, e.g. in the flow of liquids or... 

If a material of polar molecules, such as water, is exposed to a fixed or static electric field, the molecules will all rotate in an attempt to orient themselves in the direction of the field. The magnitude of separated charges of a polar molecule is defined as the dipole moment, and determines the strength of interaction with the field. The dipole moment is also a measure of the dielectric constant e. A symmetrical molecule, with no dipole moment, is said to be non-polar and does not react with an electric field. If an electric field impinging upon a polar molecule is alternating, the molecules will rotate, following reversals of field. 

As soon as a nonpolar material is exposed to a static electric field, E, dipoles become excited. That is, a local charge difference is induced within the neutral species, as the centers of gravity for the equal amount of positive and negative charges, Q, turn out to be separated by a small distance, d, generating a dipole with a dipole moment... 

The important thing to keep in mind is that whenever there is contact and separation of phases, a charge may develop that could be disastrous. Three conditions must be met before an explosion caused by static electricity can take place ... 

Nitrocellulose smokeless powder is an extremely electronegative material, and therefore, produces static electricity when brought into contact and separated from almost any other material. During the course of drying, and handling the powder after drying, BALL POWDER could acquire a considerable charge. 

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