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FLOW & LEVEL CONTROL
MANAGING STORM RISKS
Flexim ultrasonic flowmeters play a crucial role in clamping down on storm overflows
A
ccording to reports in the UK press last year, UK water companies released untreated sewage into our waterways more than a thousand times a day. And data from environmental charity ‘Surfers Against Sewage’ reveals that there were a staggering 320 raw sewage warnings issued in the very first week of 2023 alone. With increasing public concern about the unacceptable amount of sewage entering our rivers and seas, the UK government is now demanding every single water and sewerage company in England has a clear plan of action on every storm outflow, particularly those that are near to where people swim or in the vicinity of valuable habitats and wildlife.
Climate change A storm overflow occurs when the capacity of a wastewater system is exceeded due to heavy rainfall, with the excess water being discharged into local watercourses. This in turn can lead to pollution and environmental damage. With extreme weather events becoming more commonplace due to climate change, the problem is only set to increase.
It’s impossible to manage storm outflows if you don’t measure the flow rate. With the
SENSORS MEASURE THROUGH PLASTIC N
on-contact level measurement for fluid media with an accuracy of ± 2mm over a range of 0.01 to 10m is offered by the new LW2120 radar level sensor from ifm electronic. This sensor is equally suitable for use in closed tanks – either plastic or metal – or, with the addition of an accessory antenna, in open vessels such as sumps, chambers and Venturi flumes, where it can be incorporated in to a flow rate measurement system.
LW2120 sensors use an FMCW radar signal at a frequency of 80GHz to measure the level of the liquid medium and thus offer completely non-contact operation. This means they are not subject to wear and do not suffer from the build-up of contaminants. In addition, the performance and accuracy of the sensors are unaffected by the presence of steam, vapours or condensates. A further important benefit is that the radar signal can measure through plastic materials, so the sensors can be conveniently mounted above plastic tanks, such as IBC containers or chemical storage tanks.
For connections to the process control system, LW2120 sensors feature an IO-Link interface which ensures accurate data transmission even over long cables in electrically noisy environments. The IO-Link interface can also be used for remote parameterisation. To provide compatibility with conventional control systems, LW2120 sensors offer two further outputs which can optionally be configured as two switching outputs, for example to detect high and low level, or as one switching output and one 4-20mA analogue output.
www.ifm.com/gb/en
20 MAY 2023 | PROCESS & CONTROL
high performance and reliability of a clamp- on ultrasonic flowmeter, it’s possible to regain control of the situation. Providing real- time data on the flow rate of storm outflows, this valuable information can be used to monitor the amount of water flowing out of a particular area during a storm event. This is essential for managing flood risk and ensuring the safety of local residents, infrastructure and wildlife.
Using ultrasonic soundwaves to measure
the flow rate of a fluid, two transducers are safely and securely fixed to the outside of the pipe with a permanent clamp-fitting. One transducer emits ultrasonic signals into the fluid and the other one receives it. Traveling
through the fluid at a known speed, the flow rate is calculated by measuring the difference in time that it takes for the signal to travel with the flow and against the flow. This results in a time difference, Δt, and is directly proportional to flow rate. It’s also possible for the flowmeter to measure the speed of the fluid and the direction of flow. A key advantage of clamp-on ultrasonic
flow measurement is that it is non-invasive. There is no need to cut or modify the pipe, eliminating unnecessary downtime – installation is simple and cost-effective. And because there is no contact with the fluid being measured, there is absolutely no risk of contamination.
Potential penalties
At present, any water company that illegally pollutes waters can face enforcement action from the Environment Agency. But with the prosecution process often being lengthy, the government now wants to make it quicker and easier to issue penalties for environmental damage.
All options – including £250 million as an upper limit fine are being considered. There will be a public consultation in the spring to determine an appropriately high limit that sends a clear message as a serious deterrent.
Thérèse Coffey, Environment Secretary, said: “Through the largest infrastructure programme in water history, we will tackle the problem at source, with more investment on projects like the new Thames Tideway super sewer. I am making sure that regulators have the powers they need to take action when companies don’t follow the rules, including higher penalties that are quicker and easier to enforce.” Dynamic clamp-on flowmeter data monitoring provides a crucial early warning of overspill. This helps to prevent untimely discharges from storm water retention tanks, meaning the number of discharges into local watercourses is greatly reduced.
Flexim
www.flexim.co.uk
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