Description

The continuous-slot screen is widely used throughout the world for water, oil, and gas
wells, and is the dominant screen type used in the water well industry. It is made by
winding rolled wire, triangular in cross section, around a circular array of longitudinal rods.
The wire is attached to the rods by welding. Welded screens are commonly fabricated
from stainless steel.
Slot openings are manufactured by spacing successive turns of the outer wire to produce
the desired slot size. Slot openings have been designated by numbers which correspond
to the width of the openings in thousandths of an inch. A No. *0 slot screen, for example,
is an opening of 0.**0 inch.
Continuous-slot screens provide more intake area per unit area of screen surface than any
other type. This type of screen has maximum open area. For best well efficiency, the
percentage of open area in a screen should be the same as, or great than, the average
porosity of the aquifer material. Water flows more freely through a screen with a large
intake area compare to one with limited open area. The entrance velocity is low, therefore
head loss for the screen is at a minimum, thus minimizing drawdown in the well.