Background
The Athens Water Supply and Sewerage Company (EYDAP) is the largest Greek utility in its sector. Based in Galatsi in Athens, it serves 4.3 million customers in the metropolitan area of Athens with fresh water supply.
Challenge
Water losses caused by variable flow rates
As part of its ongoing non-revenue water (NRW) reduction activity, EYDAP decided to install flow-modulated PRVs in the inlet to a number of its pressure management zones. The goal was to achieve minimal critical-point (CP) pressure in the zone, regardless of demand-flow and supply-pressure variations.
Solution
Flow-modulated pressure-reducing valve
The DOROT S300 PRM(HyMod) is an automatic and autonomic pilot controlled, flow-modulated pressure-reducing valve, that is actuated by the pressure of the pipeline. Having approached Olympios – Dorot’s local partner – for support, EYDAP chose this system for its superb performance at all expected demand flow rates – it can control from no flow to maximal full open flow, without any chattering or slamming. It also proved to be the most cost-effective solution compared with electronically-controlled modulating PRVs, especially when it came to diameters of 400mm (16″) or smaller. Around 40 units of the DOROT S300 PRM(HyMod) were supplied in the first phase, in sizes ranging from DN 80 to DN 400 mm. Aquestia personnel made several visits to the site for training and to assist with the commissioning of the first units.
Advantages of the new system include:
• Reduction of burst frequency (and resulting operational costs)
• Completely hydraulic operation – no power supply requirements and no battery replacements
• High mechanical reliability with no moving parts in addition to those of a standard fixed-outlet PRV
• Fast, real-time response to variations in the demand flow rate
• Easy modulation of pressure-flow profile and optimization, with no parts replacement required
Olympios and EYDAP personal during the commissioning of one of the first DOROT S300 PRM (HyMod) systems in the project.
Results
Constant, stable pressure; longer network lifespan
Since installation of the DOROT S300 PRM(HyMod) system, there has been constant and stable pressure in the water supplied to customers throughout the day, regardless of demand flow variations, and no low-pressure complaints have been received. There has also been a clear decrease in the rate of new bursts and pipe ruptures in the zones where the DOROT S300 PRM(HyMod) valves were installed, which saves on operational costs and will extend the lifespan of the network.
The payback period for all cases of flow-modulated PRVs was estimated by the customer to be just 3 to 4 months, depending on the size of the PRV.
