Rotork actuated discharge valves are Blackhall's largest to-date
Rotork electric actuators have been specified within the terms of the company's framework agreement with Thames Water to operate two very large and highly specialised sleeve valves for critical safety-related duties at one of London's main reservoirs.
Designed and manufactured in the UK by Blackhall Engineering Ltd, the Series 3200 submerged discharge valves facilitate the rapid draw down of reservoir water levels in order to safeguard the integrity of perimeter retaining walls and dykes. Weighing more than 22 tonnes and standing 13 metres tall, each of the custom-designed valves has a maximum flow capacity 13 cubic metres (tonnes) a second. Designed using state-of-the-art computer flow modelling, the valves occupy a small footprint and deliver very high discharge capacities at low noise levels, a combination of features making them particularly suitable for populated and built-up environments.
To open the valve an internal sleeve within the 1600 mm diameter valve base is raised, allowing the water to discharge radially without creating the large plumes of spray that are associated with linear fixed cone or needle valves on similar applications.
Each valve is equipped with a top-mounted Rotork IQM modulating electric actuator and IB10 bevel gearbox, operating a stainless steel non-rising screwed stem to raise and lower the radial sleeve. The 'intelligent' Rotork actuator is programmed to operate the sleeve in stages that take account of the falling water level to maintain a constant flow rate. A data logger fitted as standard in each actuator keeps a historical record of valve operating data that can be downloaded and compared with the valve commissioning data footprint to analyse operating trends and help to minimise the requirement for routine maintenance.
The two 1600mm valves for Thames Water are the largest of their type built to-date by Blackhall Engineering Ltd, who have been supplying similar designs throughout the world for over forty years. They will be installed on the Queen Mary Reservoir, one of Londons largest man-made reservoirs, covering 700 acres in the Staines and Sunbury area and lying approximately 12 metres above the surrounding landmass.