Protection of Tanks and Silos Against Lightning

Tank and silo systems have become an attractive element for lightning impulses due to their tall and pointed structures. Moreover, tank and silo systems generally carry flammable and explosive materials. Fertilizer plants, cement production factories, oil filling facilities, etc. are particularly dangerous places, and these facilities must be lightning protected in accordance with the IEC 62305 standard. Otherwise, unwanted situations may occur as shown in the image below.

Tanks and silos must be protected from lightning according to IEC norms due to the dangers they contain.

1-External Lightning Protection System

In order to minimize the existing risk in silos and tanks, choosing passive terminals instead of active terminals will be more correct. The ionized system emitted by active terminals will increase the risk in the facility. After the lightning risk analysis is performed, creating a protection zone according to the rolling sphere method will be the most correct method. Also, if the region is an ex-proof environment, it would be correct to choose ex-proof products.

Correct protection can be provided according to IEC 62305 standard with the rolling sphere method.

In the image above, a design has been made for 3 different silos according to the building structure. All three designs have been calculated in accordance with the details in the IEC 62305-3 section.

Isolated Conductor

It is necessary to use isolated down conductors in tanks and silos, which are explosive and flammable facilities. Depending on the structure of the region, an isolated conductor resistant up to 200 kA can be selected. Also, lightning down conductors designed for ex-zones can be used in these facilities. The following factors should be considered when selecting an isolated conductor.

• First of all, the isolated conductor should be selected according to the characteristics of the area used.
• The Air Terminal system must be insulated especially on metal surfaces and the conductor must pass internally.
• Isolated conductor clips must be ex-proof and selected with S separation distance according to the zone status of the protection area.
• The conductor surface must definitely be grounded.

• The conductor must be grounded inside the air terminal and the air terminal insulated area must be at a minimum distance of 1500 mm.
• The conductor cannot be lowered from the building in unlimited length, impedance losses must definitely be calculated.
• The conductor must definitely have suitability certificates for use in Zone 1 and Zone 2.

Spark Gap and Equipotential

Again, the external lightning protection system must be brought to equipotential with a spark gap arrester. This will ensure that incoming impulses are dampened at the very first stage and will prevent resistance differences that may occur in the facility.

Lightning protection of biogas facilities

Internal Lightning Protection

Internal Lightning Protection systems are also essential for electrical protection in the facility. Throughout the facility, main panel protection, sub-panel protection, and protection of sensitive systems are required.