Practical considerations impose some restrictions on the application of isolated
ELPSs in tanks and vessels of huge dimensions. For example, observing a
minimum separation of at least 2 m between the shell of the tank and the elements
of the LPS, tanks of 30 m diameter would need to be protected by vertical masts
of 25 m height if the tanks were 15 m high and the masts were erected in a
four-vertical-mast arrangement, and the height of the vertical masts would have to
be increased as soon as either the height or the diameter of the tank needed to be
increased. Higher vertical masts are subject to mechanical and operative restrictions,
which might limit their use in a protective scheme, for example, for tanks with
huge diameters (from 40 to 85 m) commonly used to store less volatile liquids, like
crude oil, for which a self-protecting scheme could be observed as the unique
protective measure.