AVK control valves in water supply project

Following a seminar at AVK regarding leak detection and minimising water loss by means of control valves, AVK was approached by one of the attending water utilities, Strømmen Vandværk in Randers, Denmark, which was challenged with pipe fractures due to excessive pressure in the water lines.

The distribution network has a height difference of 40 meters, and the water utility placed in the high end gives a very high water pressure in the lower end of the distribution network. This results in a district within the supply area being exposed to frequent pipe fractures - the consequence of which being heavy repair costs and an increased water waste.

The water utility is already equipped with a SCADA system, but they also wanted intelligent control valves to control the pressure in defined pressure zones based on consumption and circadian rhythm. Also, it was important to the water utility to be able to close the control valves remotely via their SCADA system. With this extra feature, they will be able to close each section very easy and fast, in the case of a pipe burst. This will give the water utility control of their system - and not the other way around. A flow-meter will be installed together with each control valve. The meter also sends data to a programmable logical computer (PLC) and to the SCADA system. This way, the water utility is able to detect even small leakages and get an alarm in case the consumption rises, which indicates a leakage.

When control valves are installed with PLC control, it is possible to lower and maintain the pressure at a constant level. Additionally, it is possible to make a time schedule and lower the pressure to different set points, so the pressure during day-time would be 3 bar, and only 1.5 bar at night, when the consumption is low.

The task now is to divide the entire supply area into sections and pressure zones, and then control the supply pressure in each zone based on requirements and the build-up area. Next step will then be to test the valves installed at the borderline of different zones. This is done to ensure a tight shut-off of the pipes connecting the different pressure zones before the control valves can be installed. If you want to control the pressure within a zone, it is imperative that these valves are tight to prevent pressure from the neighbouring zone interfering the operation. In the case of more entrances, it is important that each entrance is operated by its own control valve.