The production of these Johnson screens type is by now consolidated, actually it has been produced since 1990 and it was preceded by "Anti-sand" screen, which was manufactured with an inside simple screen and produced for about a decade.
Thanks to the experience and to the advanced technological machineries, nowadays it is possible to manufacture water screen with diameters from 60 to 1000 mm and with lengths up
to 12 metres.
It is the Johnson screen type that through the past years has been employed more and more, just for its excellent technical features.
The water screen, manufactured with a trapezoidal / triangular section of the spiral wrapped wire on loading rods according to the generators of a cylinder, can have slots from 0,20 mm onwards, so as to satisfy every request and every projecting need or of installation.
As already known, spiral screen for water well, like Johnson type screens, have, with equal diameter and slot, bigger opening surfaces than the ones of other kinds of screens (bridge or simple slot screen).
The higher percentage of opened area enlarges the profit of water. In Johnson screens type, the wide opened area simplifies enormously (in comparison with other screens) the washing of the well when, for instance, it is necessary to eliminate the mud panel.
In favour of the spiral Johnson type screens there is the chance to have smaller slots than the ones of other kinds of screen.
This is a great advantage when you have to filter waters in slimy soils where it is therefore necessary that the drain is of a very low grain size and that, at the same time, it cannot pass through the screen for water well itself.
Moreover, in rotation perched wells by inverted circulation, if the hollow space hole/casing is very small and such not to allow the forming of artificial drains,
it is better to employ these Johnson type screens with slots of 0,20 mm.