Static Electricity 2000 Edition

D.1.12 Charging, Triboelectric.
Static electric charging that
results from contact or friction between two dissimilar materi-
als; also known as frictional charging and contact-separation
charging. Triboelectric charging is the most familiar, yet least
understood, charge generation mechanism. Triboelectric
charging results from contact or friction between two unlike
materials. The amount of charge generated in this way is
dependent primarily on the nature of contact, the intrinsic
electrical and static electric properties of the materials
involved, and the prevailing conditions of humidity and tem-
perature. An indication of the tendency of materials to accept
static electric charge in this way is given by the triboelectric
series. Recent studies indicate that the amount of charge
transferred depends not only on the composition of the mate-
rials but also the capacitance of the junction. Examples of tri-
boelectric charging are as follows:
(1) Pneumatic transport of powders along pipes
(2) High-speed webs of synthetic materials moving over roll-
ers
(3) Charging of the human body as a person walks across a
carpet
(4) Extrusion of plastics or the ejection of plastic parts from
a mold
Table D.1.12 illustrates typical electrostatic voltages
observed as a result of triboelectric charging at two levels of
relative humidity (RH).
D.1.13 Conductive Floor.
Flooring that has an average resis-
tance between 2.5 
× 10
3
ohms and 1 
× 10
6
ohms when mea-
sured using specified electrodes placed a specified distance
apart. (See NFPA 99, Standard for Health Care Facilities.)
D.1.14 Conductive Hose.
Hose that has an electrical resis-
tance of less than 10
3
ohms per meter, when measured
between the end connectors.