Page 341 - Water Loss Control

310 Cha pte r Ei g h tee n

Pressure Control can be Implemented in Subsectors

34 33
32
35

Av.. Ermane Marchettl 41 31 Level 700

Reservoir
Rua do Curtume
Level 795

FIGURE 18.6 Pressure management in subsectors.

Sectorization in its simplest form does not require the implementation of costly
ACVs and controllers, however without them, in many cases it is not completely effi-
cient. Many systems that have had sectorization in place for many years are finding that
it is very cost-effective to implement more advanced control in addition to the basic
control already in place.

18.3.2 Pump Control
Many utilities use pump control as a method of controlling system pressure. Pumps
will be activated or deactivated depending upon system demand. This method is effec-
tive if the reduced level of pumping (usually at night) can still maintain reservoir levels.
With recent energy conservation concerns this methodology should be carefully
reviewed, as to the efficiency of energy use. The pump(s) may operate outside of the
designed profile if subjected to upstream valve throttling or demands outside of the
design limits. Inefficient pumps can cause huge increases in electricity consumption
and in some cases expensive fines for over use during peak times.
Properly controlled pumps in particularly with variable speed drives can however
provide very effective system pressure control.

18.3.3 Throttled Line Valves
Many system operators recognize the need for reducing system pressure and partially
close a gate or butterfly valve to create a head loss and reduce pressure. This method is
the least effective, as the head loss created will change
as system demand changes. At night when a distri-
bution system needs the least pressure, the pressure
Throttled system valves are will be higher and during the day when the distribu-
the least effective way of con- tion system needs the most pressure to supply
trolling pressure. demand, the pressure will be lower. This creates a
classic case of an upside down zone.