Pump discharge control valve for the water industry

Australia’s aging water distribution infrastructure and growing population are placing a strain on water networks, leading to increased demands for maintenance and capacity upgrades. This is a significant challenge for utilities, but the correct equipment selection can bring about new efficiencies through increased operational reliability and functional performance.

Several recent projects in Sydney highlighted these efficiency possibilities with potable water pump station capacity upgrades. These projects involved upgrading pumps, piping systems and delivery control valves with specific automation features. The piping systems ranged from 200 to 900 mm, with system pressure ≥ 35 bar and each station having a uniquely different functional demand.

Improved efficiencies at these pump stations were achieved following a thorough investigation, identifying the design of valve most suited to the arduous conditions encountered during the opening and closing sequences with the pump running at full RPM. The importance of this valve within a pump station is essential in reducing mains ruptures, particularly with aging piping infrastructure.

Delivery control valves, or DCV, is a term applied to the function of a slow operating on/off isolation valve installed downstream of a fixed speed or variable speed pump. A delivery control valve’s primary purpose is to mitigate the effects of pressure surges within a pressurised rising main during pump start/stop sequences. The valve opens and closes at an adjustable speed, providing a smooth, predictable transition of pump discharge pressure and volume into the network lines. The upshot of slow cycling is to sustain cavitation transients which the valve must be capable of withstanding over a long operation life cycle.

With the application pressures ≥ 35 bar, the conditions meant that the high-pressure differentials that the valve would experience resulted in high mechanical contact loads at the seating interfaces and the bearing journal of the valve. Together with these elevated pressures was the high-level demand for continuous operation. Pump discharge control valves need to be consistently reliable with predictable valve availability, with little to no maintenance while operating in high velocity and turbulent conditions over 20 to 30 years.

During the initial tender stage, the successful contractor selected and purchased a product for the application. Following the installation and during commissioning, the valves failed to perform the functional requirements and the client classified the valves as non-conforming. The contractor installed two other valves from the same valve supplier. Both options failed due to external leakage through the valve shaft, premature mechanical wear and corrosion of the disc edge and seating element.

Following the client’s investigation of the failures and compliance with the specification, the client decided to undertake the selection process internally, ensuring a suitably compliant and fit-for-purpose solution.

EBRO Armaturen’s HP300 series triple eccentric butterfly valve was viewed as the best-fit solution, installed in 2021, and continues to provide the availability and controllability specified by the client.

Prior experience with pump station delivery control valves across Australia and New Zealand meant that EBRO Armaturen Pacific provided a tailored solution comprising a unique disc-to-shaft positioning and orienting of the valve in such a way as to assist pump start-up.

When reviewing a particular valve design for a delivery control valve application, consider the services of a company with industry or application expertise. Having a technical understanding of the valve design when reviewing application parameters allows one to highlight concerns or nominate particular features to enhance performance.

The HP300 series high-performance butterfly valve is precision engineered with a triple eccentric construction available in stainless or carbon steel materials. Various options are available for the seating and shaft sealing elements, with a leakage rate of A (EN12266). Thus, it is suitable for water, refineries, power/energy and chemical applications. Its inherent features make it suitable for extreme temperature and pressure conditions up to 63 bar, and temperature ranges from -60 to 650°C (higher temperatures on request).

Images: Supplied