Grounding static electricity

Windblown particles have been observed to build up quite a hefty charge by contact electrification on insulated bare wire fences, and in general, on any conducting surface that is isolated from ground. Static electricity is also formed by make and break contact as you exit a vehicle or can be observed as static cling with various types of fabric. A harmless discharge to the door... 

Toluene is a notoriously poor electrical conductor even in grounded equipment it has caused several fires and explosions from static electricity. Near normal room temperature it has a concentration that is one of the easiest to ignite and, as previously discussed, that generates maximum explosion effects when ignited (Bodurtha, 1980, p. 39). Methyl alcohol has similar characteristics, but it is less prone to ignition by static electricity because it is a good conductor. Acetone is also a good conductor, but it has an equihbrium vapor pressure near normal room temperature, well above UFL. Thus, acetone is not flammable in these circumstances. 

In most chemical areas, grounded persons can wear any type of clothing safely. For the unusually sensitive environments hsted above, antistatic or conductive clothing shoiild be worn, and persons must be grounded. Removal of outer garments in a flammable location can cause hazardous discharges and should be avoided (NFPA 77, Static electricity, para. 2-2, 1993). 

Klinkenberg, A., Production of static electricity by movement of fluids within electrically grounded equipment, Proceedings Fourth World Petroleum Congress, Sect VII-C. Paper No. 5. 253-64, Carlo Colombo, Rome, 1955. 

Note that grounding a tank truck will not prevent ignition of vapor by a discharge of static electricity. Grounding will prevent a discharge from the tank to earth, but it will not prevent a discharge from the liquid in the tank to the tank or to the filling arm. 

Generally static electricity can be overcome or controlled by several basic approaches - bonding, grounding, and controlled generation. 

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