SU DAĞITIM SİSTEMLERİ

WATER DISTRIBUTION SYSTEM HANDBOOK_L.W.MAYS
PAGE 31
Major functional components : source development, raw water transmission, raw water storage, treatment, finished water storage, finished water distribution

Nodes are classified as junction nodes, where inflow and outflow is known and fixed grade nodes, they take form of tanks or large constan-pressure mains.

Control valves regulate the flow or pressure. If conditions exist for flow reversal, the valve will close and no flow will pass. The most common type is pressure reducing valve (PRV), which is placed at pressure zone boundaries to reduce pressure. The PRV maintains a constant pressure at the downstream side for all flows. hl varies, depending upon the downstream pressure and not on the flow in the pipe. There are many other types of valves, isolation valves to shut down a segment, direction control (check) valves to allow the flow of water in only one direction, such as swing check, rubber-flopper, slenting check disk check, double door and vacuum-breaker valves to control flow.

Distribution system storage is needed to equalize discharge near an efficient operating demands. Distribution storage is closely associated with water tank. Tanks are usually made of steel and can be built at ground level or be elevated at a certain height from the ground. The water tank is used to supply water to meet the requirements during high system demands or during emergency conditions when pumps cannot adequately satisfy the pressure requirements at the demand nodes.

The higher the pump discharge, the lower the pump head becomes. Thus, during the peried of peak demands, the amount of available pump head is low.

The most commonly used type of pump used in water distribution systems is the cenrifugal pump.

The flow measuring of water mains involves electromagnetic meters, ultrasonic meters, propeller or turbine meters, displacement meters, multijet meters, proportional meters, compound meters.

Goals for water distribution operation :
1.Maximize reliability, achieved by keeping the maximum amount of water in storage in case of emergencies, such as pipe breaks and fires.
2.Minimize energy costs, achieved by operating pumps against as low a head as possible (min water in storage) near the best efficiency point for the pump.
3.Meet water quality standards, which involves minimizing the time the water is n the distribution systems and tanks and is achieved by having storage tanks levels fluctuate as much as possible.

The control of pumping operations can range from a simple manual operation an individual pump or valve to the use of a Supervisory Control and Data Acquisition (SCADA) system. Most utilities have some level of a SCADA system in place for use in operation of the system.

The SCADA system would provide not only real time hydraulic parameters but also realtime water quality information to the network model.

System : Demand forecast - Network - Optimization (SCADA in all process)