Uncontrolled pressure surges in pipelines costs the water industry millions of pounds every year, causing burst pipes, structural damage, negative pressures and colossal water wastage. Negative pressure directly contravenes Drinking Water Inspectorate (DWI) legislation due to the risk of contamination. QED are specialists in controlling pressure surges, providing cost effective solutions.
Surge is inevitable when pumping water; it can occur when the flow rate of pumps at a pumping station is altered, valves opened/closed along the pipeline, or uncontrolled pump-trips due to power cuts. These can lead to extreme pressures fluctuations which, if not controlled, can lead to disastrous consequences including burst pipes, unnecessary water loss and supply disruptions. Negative pressures are far more prevalent than high pressures, considerably more destructive, as well as contravening DWI compliance on potable water systems if wholesomeness cannot be assured. 100% leakage reduction of any pumping main is impossible until potential surge pressures in the pumping main are reviewed.
A Hydraulic Study is the first step in the risk management of any pipeline, new or existing, and where the magnitude of the risk is defined. The inclusion of a Surge Vessel onto the pumping main is the ONLY solution for addressing ALL surge pressure scenarios. The hydraulic study will specify both the total Surge Vessel volume and the critical initial air volume (IAV) necessary to protect the pumping main. This information then forms part of the system design criteria, along with vessel design code, Pressure Equipment Directive, site criteria, control method, HSE considerations and TOTEX requirements.
Once in service, maintaining the specified IAV is critical to ensure the correct level of surge protection is provided to the pumping main. If the specified IAV is allowed to “drift” then the level of surge protection provided to the pumping main also drifts.
Keeping the Hydraulic Study document and a detailed pipeline profile is important so the hydraulic consequences of any future system modifications can be assessed. At worse the existing Surge Vessel may no longer be appropriate, or at least it may just require a modified control setting.
When any changes are made to the network such as new pumps or the mains extended, it is imperative that any existing surge control measures are also reviewed to insure they are still appropriate.