Boars Head Service Reservoir provides fresh drinking water to just under 6,000 customers across 3 District Management Areas (DMAs) near Wigan, Lancashire.
The site had been operating for several years using a 12″ (300mm) actuated butterfly valve to control the tank inlet water supply at a predetermined minimum and maximum water level. Site conditions made managing the reservoir levels more cumbersome than it needed to be.
Firstly, the site does not have accurate flow metering so the valve operation was spindle % position only, requiring the levels to be controlled manually by one of the utility operators who continually adjusted the % position. This proved very challenging and time consuming. In addition, there is a second reservoir fed from the same system that Boars Head has, which impacts the balancing level.
Secondly, the site had a history of pressure transients due to rapid changes in flow velocity caused by uncontrolled actuator movements. Due to limitations in valve design, the utility struggled to control levels accurately and wanted to explore an automated and effective method of operation, and also provide a diurnal level control pattern whilst managing water turnover.
By adding the Cla-Val VC-22D Valve Controller, the utility was able to retain the use of the existing valve and achieve automation and control of the reservoir levels.
The controller is pre-loaded with a wide variety of typical valve applications (ValvApp). This allowed the utility to use the ‘fill & drain” ValvApp tool to automatically control levels between a pre-set range. By taking the 4-20mA reservoir level signal back to the VC-22D, operators were able to program a minimum and maximum level threshold (between 11.48 ft (3.5m)hd and 18 ft (5.5m)hd) and create two % values to output to the valve actuator to facilitate filling and draining of the tank (1% to drain and 5.5% to fill).
The VC-22D Controller provided a complete solution. It removed transient behaviour – by keeping the actuation on the butterfly valve under 12% spindle movement to ensure open and close action was slow and smooth, it also provided a diurnal level pattern across a 7-day period by utilising the preprogramed fill and drain %. This provides adequate water turnover between the l high(HI) and low level (LO) thresholds. In the event of a power failure, the actuator is set to default % to ensure that the reservoir maintains an adequate supply of water.
The Boars Head Service Reservoir is now managing the flow with all elements accounted for, providing customers with a consistent supply of new water. “We call this the network calming approach,” said David Humphrey, Managing Director at Cla-Val UK, “Controllers can be a simple fix to improving the smooth operation of struggling valves, and the more sophisticated a controller is, the more functionality you have including measuring flow, automation, setting precautionary fail-safe limits, and so on.”
