Conductivity

Non-conductive materials are the so-called static accumulators

–Liquids are considered to be non-conductors when they have conductivities less than 50 pS/m (pico Siemens/metre). Such liquids are often referred to as static accumulators.
–Typically Petroleum products, such as clean oils (distillates), chemical solvents or highly refined fuels

Semi-conductive materials are known as static non-accumulators

–Typically black oils (containing residual materials) or crude oils

Under normal conditions, gases are highly insulating and this has important implications with respect to mists and particulate suspensions in air and other gases. Charged mists are formed during the ejection of liquid from a nozzle, for example:

• Petroleum products entering an empty tank at high velocity.
• Wet steam condensing.
• Water from tank washing machines.
• Crude oil during crude oil washing.