<p style="\"margin:" 0px="" *5px;="" padding:=""
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font-family:="" vertical-align:="" baseline;\"="">Water Well
Filter Pipe s are manufactured from a variety of materials and
range from crude hand-
made contrivances to highly efficient and long-life models made on
machines. The value
of a screen depends on how effectively it contributes to the
success of a well. Important
screen criteria and functions include:
Criteria:
1. large percentage of open area
2. non clogging slots
3. resistant to corrosion
4. sufficient column and collapse strength
Functions:
1. easily developed
2. minimal incrusting tendency
3. low head loss through the screen
4. control sand pumping in all types of aquifers
Continuous-Slot Screen
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.
