Safely static charge

Severe hydroprocessing required to produce ultra-low sulfur fuel removes most of the polar organic compounds from the fuel. The resulting product is virtually unable to effectively dissipate static charge as it builds in moving fuel. Instead, electrical discharge into pockets of gas within a pipeline or into air and vapors as fuel is being dispensed can occur. An explosion may result. Low levels of a fuel-soluble electrical conductivity improver to ultra-low sulfur fuel can help restore fuel electrical conductivity to safe levels. 

This author does not favor the use of static charge meters because their use is subject to operator diligence. It is a safer procedure to avoid the conditions which promote static charge accumulation as a matter of routine. Low ambient humidity is the chief contributing factor in the accumulation of hazardous static charges. In many desert areas (which seem to be favorites for ordnance work), the daytime ambient humidity is below 20% and in temperate regions, winter-time air, and indoor air, has likewise a low humidity. For this reason, also, air conditioned air, in the absence of artificial humidification, should be strictly controlled. In order to maintain a relatively safe humidity above 50% RH, the use of evaporative coolers is helpful in a desert environment. The matter of humidity control in pyrot processing plants was recently considered by Avrami et al (Refs 55 56) Miscellaneous Laboratory Hazards... 

Flammable liquids are considered particularly static-prone if their elec trical conductivity is within the range of 0.1 to 10 pS/m. If no particulates or immiscible liquid are present, these prodlic ts are considered safe when their conductivity has been raised to 50 pS/m or higher. Blending operations or other two-phase mixing may cause such a high rate of charging that a conductivity of at least 1000 pS/m is needed for safe charge dissipation (British Standard 5958, part 1, Control of Undesirable Static Electricity, para. 8, 1991). 

Cationic surfactants contain a positively charged headgroup and are typically used as conditioners to improve hair manageability and reduce static. Cationic surfactants are especially irritating to eyes when used in high concentrations but are safe and useful in low amounts. Quatemium-15 (chloroallyl methanamine chloride, Fig. 7.9.4) is a cationic surfactant included in shampoo formulations... 

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