SMART CITY ENHANCEMENTS: How level measurements can be digitised using modern 80 GHz Radars
Today’s digital improvements in water and wastewater are centred on measuring the level, flow, pressure and also quality analysis of water running through sewage lines, open channel and under
manhole, says Alexis Alexander, Product Manager, VEGA
As the working population is moving closer to cities, the existing infrastructures may not be efficient in handling and optimising various services to the concentrated population.
Cities, roads, power and water networks were designed with outdated technologies that could cater to a certain population which have now exponentially concentrated to urban localities.
Smart city enhancements are sought out to improve our capabilities in handling better services from these existing infrastructure. Today, they are also integral to the initial design while developing new infrastructure to accommodate for the future influx of population or even environmental conditions.
Smart city developments focus primarily on measuring parameters that can be used to optimize a lot of processes. Typical measurement ‘wish lists’ include monitoring of traffic congestion, city lighting, fire detection, energy monitoring, inventory, logistics, internet data consumption etc.
As governments and private companies are
24 researching and deploying solutions to meet these requirements, water and waste management services have seen massive improvements by digitization using the Internet of Things (IOT).
These improvements are centred on measuring the level, flow, pressure and also quality analysis of water running through sewage lines, open channel and manhole levels.
Pressure transmitters have been historically used to measure water level. Bubblers were first used where air was pumped into the fluid and the back pressure was measured by a compact sensor.
The technology soon was replaced by hydrostatic submersible sensors for obvious reasons as the pneumatic airlines would clog. In submersible sensors, the head pressure exerted by the water column is measured directly by the sensor membrane to infer the level.
They worked well and met their limits only when sludge build-up would block the pressure sensor diaphragm from measuring the fluid. This is not uncommon in wastewater networks due to the nature of the solids conveyed through the fluid. However, if maintained the abrasive and chemically resistant ceramic diaphragms lasts very long.
Nevertheless, an immersible solution has its inconveniences especially when it came to inventory spares. The hunt of a non-contact solution brought us to an obvious and available choiceultrasonic technology.
They simply measured distance by emitting an ultrasound and measuring the time for the reflection, pretty much like bats! Ultrasonic sensors are widely used in level, distance, car parking detection, counters and other measurements.
A decade ago, these devices were definitely the most preferred low cost solution. In both water and waste water applications they fared well, but had their limitations. Ultrasonic transmitters measured incorrectly under varying process and environmental conditions.
They could not be considered for pressurized or changing temperature application because of the limitation of the ultrasound itself. Ultrasonic frequencies used air as the medium to propagate. If the medium changes due to these conditions, the ultrasonic wave is affected and hence the measurement.
Additionally, if condensation or buildup would cover up the transducer face, it would normally be inferred as a full vessel. On the hand other if the ultrasonic sensors are flooded, which happens very often in a closed sewer network, they would report an incorrect value misguiding the operator to take the wrong decision. This is because of the inherent dead zones where the reflections cannot be measured.
Ultrasonic sensors have done most of the heavy lifting in measurements in water networks. But over time users have looked forward for a more reliable method of measurement.
As more manufacturers are opting out of this technology and migrating to other non-contact solutions using microwaves or lasers; ultrasonic sensors would be harder to find and more importantly difficult to stock for maintenance spare
inventory.
WHAT MAKES RADAR SENSORS THE LEVEL MEASUREMENT OF THE FUTURE? Radar level sensors were always destined to be the lasting sensor of the future, as they can unaffectedly measure through any pressurized and temperature conditions. It had always been the price and size of the instrument that limited their use to demanding applications like in the oil and gas.
Normally instrument designers felt radars were an expensive overkill for the job while ultrasonic was just cheaper to use. Today however, as technology has evolved, costs of manufacturing the radar, which were unaffordable for the water sector, have dwindled.
Since 2015, VEGA has been investing heavily in perfecting the 80 GHz radar technology. On using a higher frequency the radar beam sharpens as much as 3 degrees, which otherwise was previously broader.
This highly narrow beam can easily avoid internals and provide a high dynamic range which is useful in difficult-to-measure conditions like foam. The electronics that was designed around a circuit board is now sized into a microchip which has brought the size of the complete sensor down.
Every model of the latest radars comes with a small form factor packed with the complete processing capability even including digital protocols like Modbus and SD12.
It is not just the size that have made a remarkable improvement. The designs catered to cost effective installations even in hazardous areas. Due to the collection of methane and hydrogen sulphide generated from the decaying waste, sensors with no safety protection, can create a spark which can lead to a possible explosion.
The completely potted design of the newer radars allows an installation in Zone 2 areas, that otherwise needed expensive intrinsically safe barriers. Also, speaking of manholes and sewers in both water and waste water networks, the ingress protected design allows the sensor to be withstand 30 meters of water when unintentionally submerged.
Underground water networks have open channel flow meters using level sensors. For instance during an event of heavy rains the level increases indicating that the flow has increased. Pumping stations need to manage multiple pumps in discharging excessive water to make sure the networks are not flooded. Early information from sensor data helps the city prepare for this.
In case of sewer lines, the manholes get flooded when clogged or improperly management.
SELF-POWERED LEVEL SENSORS FOR IOT APPLICATIONS
Monitoring levels in natural water bodies like rivers, streams, lakes, and aquifers are necessary and part of several government interests to manage depleting drinking water resources.
Even monitoring reservoirs like dams using data, can prevent a percentage of disasters. Smart city measurements intend on connecting all these level measurements to a central SCADA which allows a central remote management to prevent an untimely event of a flood or even a looming danger of low water resources.
Remote operations have a problem with power supply to maintain the measurements. Batteries are used considering these measuring units. Sensors, especially those of the past, were not designed keeping batteries in mind.
It is only recently we see the foray of batteries or the use of solar panels. But if sensors are not optimized these batteries will turn out to be bulky or will have to be frequently changed.
Using sensors for measuring several times during the day, demands them to have low power consumption. The VEGAPULS 10,20 &30 80 GHz radars have the lowest power consumption in the market.
This make them perfect for IIOT applications where remote measurements are very common. Solutions for smart city measurements are mostly battery operated and to meet this requirement newer radio technology standards like LTE-M and NB-IoT are being introduced.
These standards are designed so that information payload, transmission time and power consumption are highly optimized. The VEGAPULS Air is a self-powered radar level transmitter inheriting the features of the 80 GHz radar and supplemented by the capabilities of data transmission using LTE-M and NB-IoT.
The future proof design allows sensor values to be transmitted directly to an IoT database which can be done hazzle free by vendors like VEGA.
LORA – an abbreviation of Long Range Low Power radio standard, has been popularizing the use of a wireless network for acquiring instrument data. LORA powered sensors can relay information to gateways placed up to a distance of 10kms.
With the capability of one LORA gateway gathering several sensor data over a huge distance, it is an ideal solution for smart cities, industries that need their own networks and even global sensor networks.
Vendors like VEGA offer a highly secure network through their certified gateways and database. Equipped with ISO27001 and SOC2 certification, the data from any sensor sources are stored securely in these databases with a highly intuitive interface. The only way for the information to be retrieved is through secure APIs or OPC UA.
Using smart sensors to retrieve measured values across a Wide Area Network, have provided us a chance to analyze a huge amount of information. Previously such huge data acquisition methods were only in the hands of big tech organizations. But with the introduction of low cost and efficient devices from smart sensors to machines, we now easily gather a huge pool of data that can be used to simulate and even model conditions which helps us to make more calculated decisions. In the case of stormwater and sewer networks; events like a clogs, leakage, excessive rains and several other conditions can be predicted in advance. With an extra layer of machine learning applied on such a huge data sets, more accurate control methods can be defined which will enhance our methods of managing our resources better.
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