Lightning Master – Static Solutions & Lightning Protection

Charge dissipates from a fluid into points and sharp edges, not flat surfaces. That is why charge does not readily dissipate into the shell of a metal tank – it is flat. This allows the charge to accumulate at a rate faster than it dissipates. Because the static charge eventually relaxes, an incendive spark is most likely while the charging mechanism is active. The wild card in tank protection has always been equalizing the bound charge on the stored product. Even in a steel tank, there is nothing to help dissipate the bound charge on the stored product. The liquid simply lies against the side of the tank, and the charge must inductively couple onto the flat surface. It takes time for the potential to relax, allowing the static charge to accumulate faster than it dissipates.

Lightning Master has designed an in-tank static drain consisting of a stainless steel cable with stainless steel electrodes inserted into the wind of the cable. In fixed roof tanks, the drain is installed through the thief hatch, and in floating roof tanks, it is attached to the floating roof and sides or bottom of the tank. The thousands of electrically sharp points provide a low-resistance path for bound charge to leave the liquid and vapor space. It dissipates the charge on the product, allowing it to relax much more quickly. This allows the charge to dissipate faster than it accumulates.

Lightning becomes an issue when it strikes the floating roof, the tank or nearby. Ignition is not normally caused by the heat of the lightning channel igniting venting vapours. It is caused by arcing from the secondary effect of lightning. A thunderstorm is an electrically charged cloud mass with a charge, usually negative, at its base. That charge induces an opposite charge, usually positive, on the surface of the Earth beneath it.

When lightning attaches to a tank or other object on the surface of the Earth, the charge at the point of attachment changes dramatically and almost instantly. The surrounding ground charge rushes toward the point of the strike. If that in-rush of charge crosses a gap, it may arc. If that gap is between the floating roof and the side of the tank shell, and there are flammable vapours present, those vapours may ignite. The MAGS system provides preferred path for that charge to travel, preventing arcing and ignition.