High frequency monitoring needed to protect UK rivers!

29/06/2018
Nigel Grimsley from OTT Hydrometry describes relatively new technologies that have overcome traditional barriers to the continuous monitoring of phosphate and nitrate.

The science behind nutrient pollution in rivers is still poorly understood despite the fact that nitrate and phosphate concentrations in Britain’s rivers are mostly unacceptable, although an element of uncertainty exists about what an acceptable level actually is. Key to improving our understanding of the sources and impacts of nutrient pollution is high-resolution monitoring across a broad spectrum of river types.

Background

Green Box Hydro Cycle

Phosphates and nitrates occur naturally in the environment, and are essential nutrients that support the growth of aquatic organisms. However, water resources are under constant pressure from both point and diffuse sources of nutrients. Under certain conditions, such as warm, sunny weather and slow moving water, elevated nutrient concentrations can promote the growth of nuisance phytoplankton causing algal blooms (eurtrophication). These blooms can dramatically affect aquatic ecology in a number of ways. High densities of algal biomass within the water column, or, in extreme cases, blankets of algae on the water surface, prevent light from reaching submerged plants. Also, some algae, and the bacteria that feed on decaying algae, produce toxins. In combination, these two effects can lower dissolved oxygen levels and potentially kill fish and other organisms. In consequence, aquatic ecology is damaged and the water becomes unsuitable for human recreation and more expensive to treat for drinking purposes.

In its State of the Environment report, February 2018, the British Environment Agency said: “Unacceptable levels of phosphorus in over half of English rivers, usually due to sewage effluent and pollution from farm land, chokes wildlife as algal blooms use up their oxygen. Groundwater quality is currently deteriorating. This vital source of drinking water is often heavily polluted with nitrates, mainly from agriculture.”

Good ecological status
The EU Water Framework Directive (WFD) requires Britain to achieve ‘good status’ of all water bodies (including rivers, streams, lakes, estuaries, coastal waters and groundwater) by 2015. However, only 36% of water bodies were classified as ‘good’ or better in 2012. Nutrient water quality standards are set by the Department for Environment, Food & Rural Affairs (DEFRA), so for example, phosphorus water quality standards have been set, and vary according to the alkalinity and height above mean sea level of the river. Interestingly, the standards were initially set in 2009, but in 75% of rivers with clear ecological impacts of nutrient enrichment, the existing standards produced phosphorus classifications of good or even high status, so the phosphorus standards were lowered.

Highlighting the need for better understanding of the relationships between nutrients and ecological status, Dr Mike Bowes from the Centre for Ecology & Hydrology has published research, with others, in which the effects of varying soluble reactive phosphate (SRP) concentrations on periphyton growth rate (mixture of algae and microbes that typically cover submerged surfaces) where determined in 9 different rivers from around Britain. In all of these experiments, significantly increasing SRP concentrations in the river water for sustained periods (usually c. 9 days) did not increase periphyton growth rate or biomass. This indicates that in most rivers, phosphorus concentrations are in excess, and therefore the process of eutrophication (typified by excessive algal blooms and loss of macrophytes – aquatic plants) is not necessarily caused by intermittent increases in SRP.

Clearly, more research is necessary to more fully understand the effects of nutrient enrichment, and the causes of algal blooms.

Upstream challenge
Headwater streams represent more than 70% of the streams and rivers in Britain, however, because of their number, location and the lack of regulatory requirement for continuous monitoring, headwater streams are rarely monitored for nutrient status. Traditional monitoring of upland streams has relied on either manual sampling or the collection of samples from automatic samplers. Nevertheless, research has shown that upland streams are less impaired by nutrient pollution than lowland rivers, but because of their size and limited dilution capacity they are more susceptible to nutrient impairment.

References
• Bowes, M. J., Gozzard, E., Johnson, A. C., Scarlett, P. M., Roberts, C., Read, D. S., et al. (2012a). Spatial and temporal changes in chlorophyll-a concentrations in the River Thames basin, UK: are phosphorus concentrations beginning to limit phytoplankton biomass? Sci. Total Environ. 426, 45–55. doi: 10.1016/j.scitotenv. 2012.02.056
• Bowes, M. J., Ings, N. L., McCall, S. J., Warwick, A., Barrett, C., Wickham, H. D., et al. (2012b). Nutrient and light limitation of periphyton in the River Thames: implications for catchment management. Sci. Total Environ. 434, 201–212. doi: 10.1016/j.scitotenv.2011.09.082
• Dodds, W. K., Smith, V. H., and Lohman, K. (2002). Nitrogen and phosphorus relationships to benthic algal biomass in temperate streams. Can. J. Fish. Aquat Sci. 59, 865–874. doi: 10.1139/f02-063
• McCall, S. J., Bowes, M. J., Warnaars, T. A., Hale, M. S., Smith, J. T., Warwick, A., et al. (2014). Impacts of phosphorus and nitrogen enrichment on periphyton accrual in the River Rede, Northumberland, UK. Inland Waters 4, 121–132. doi: 10.5268/IW-4.2.692
• McCall, S. J., Hale, M. S., Smith, J. T., Read, D. S., and Bowes, M. J. (2017). Impacts of phosphorus concentration and light intensity on river periphyton biomass and community structure. Hydrobiologia 792, 315–330. doi: 10.1007/s10750-016-3067-1

Monitoring technology
Sampling for laboratory analysis can be a costly and time-consuming activity, particularly at upland streams in remote locations with difficult access. In addition, spot sampling reveals nutrient levels at a specific moment in time, and therefore risks missing concentration spikes. Continuous monitoring is therefore generally preferred, but in the past this has been difficult to achieve with the technology available because of its requirement for frequent re-calibration and mains power.

High resolution SRP monitoring has been made possible in almost any location with the launch by OTT Hydromet of the the ‘HydroCycle PO4’ which is a battery-powered wet chemistry analyser for the continuous analysis of SRP. Typically, the HydroCycle PO4 is deployed into the river for monitoring purposes, but recent work by the Environment Agency has deployed it in a flow-through chamber for measuring extracted water.

The HydroCycle PO4 methodology is based on US EPA standard methods, employing pre-mixed, colour coded cartridges for simple reagent replacement in the field. Weighing less than 8kg fully loaded with reagents, it is quick and easy to deploy, even in remote locations. The instrument has an internal data logger with 1 GB capacity, and in combination with telemetry, it provides operators with near real-time access to monitoring data for SRP.

The quality of the instrument’s data is underpinned by QA/QC processing in conjunction with an on-board NIST standard, delivering scientifically defensible results. Engineered to take measurements at high oxygen saturation, and with a large surface area filter for enhanced performance during sediment events, the instrument employs advanced fluidics, that are resistant to the bubbles that can plague wet chemistry sensors.

Environment Agency application
The National Laboratory Service Instrumentation team (NLSI) provides support to all high resolution water quality monitoring activities undertaken across the Agency, underpinning the EA’s statutory responsibilities such as the WFD, the Urban Waste Water Directive and Statutory Surface Water Monitoring Programmes. It also makes a significant contribution to partnership projects such as Demonstration Test Catchments and Catchments Sensitive Farming. Technical Lead Matt Loewenthal says: “We provide the Agency and commercial clients with monitoring systems and associated equipment to meet their precise needs. This includes, of course, nutrient monitoring, which is a major interest for everyone involved with water resources.”

Matt’s team has developed water quality monitoring systems that deliver high resolution remote monitoring with equipment that is quick and easy to deploy. There are two main options. The ‘green box’ is a fully instrumented cabinet that can be installed adjacent to a water resource, drawing water and passing it though a flow-through container with sensors for parameters such as Temperature Dissolved Oxygen, Ammonium, Turbidity, Conductivity pH and Chlorophyll a. Each system is fitted with telemetry so that real-time data is made instantly available to users on the cloud.

Conscious of the need to better understand the role of P in rivers, Matt’s team has integrated a HydroCycle PO4 into its monitoring systems as a development project.
Matt says: “It’s currently the only system that can be integrated with all of our remote monitoring systems. Because it’s portable, and runs on 12 volts, it has been relatively easy to integrate into our modular monitoring and telemetry systems.

“The HydroCycle PO4 measures SRP so if we need to monitor other forms of P, we will use an auto sampler or deploy a mains-powered monitor. However, monitoring SRP is important because this is the form of P that is most readily available to algae and plants.”

Explaining the advantages of high resolution P monitoring, Matt refers to a deployment on the River Dore. “The data shows background levels of 300 µg P/l, rising to 600 µg P/l following heavy rain, indicating high levels of P in run-off.”

Nitrate
Similar to phosphates, excessive nitrate levels can have a significant impact on water quality. In addition, nitrates are highly mobile and can contaminate groundwater, with serious consequences for wells and drinking water treatment. Nitrate concentrations are therefore of major interest to the EA, but traditional monitoring technology has proved inadequate for long-term monitoring because of a frequent recalibration requirement. To address this need, which exists globally, OTT Hydromet developed the SUNA V2, which is an optical nitrate sensor, providing high levels of accuracy and precision in both freshwater and seawater.

The NLSI has evaluated the SUNA V2 in well water and Matt says: “It performed well – we took grab samples for laboratory analysis and the SUNA data matched the lab data perfectly. We are therefore excited about the opportunity this presents to measure nitrate continuously, because this will inform our understanding of nitrate pollution and its sources, as well as the relationship between groundwater and surface water.”

Summary
The new capability for high-resolution monitoring of nutrients such as phosphorus will enable improved understanding of its effects on ecological status, and in turn will inform decisions on what acceptable P concentrations will be for individual rivers. This is vitally important because the cost of removing P from wastewater can be high, so the requirements and discharge limits that are placed on industrial and wastewater companies need to be science based and supported by reliable data. Similarly, nitrate pollution from fertilizer runoff, industrial activities and wastewater discharge, has been difficult to monitor effectively in the past because of the technology limitations. So, as improved monitoring equipment is developed, it will be possible to better understand the sources and effects, and thereby implement effective prevention and mitigation strategies.

@OTTHydrometry @EnvAgency @CEHScienceNews #Water #Environment

Helping provide reliable flood protection in Switzerland.

11/04/2018

Extreme weather is becoming increasingly common throughout the world, making flooding a growing threat. Flood defence measures have traditionally been based on mechanical equipment, but innovative automation technology can now be used to provide greater protection for people and the local environment. AWA – the Office for Water and Waste in the Swiss canton of Berne – is using this latest technology to regulate water levels at the region’s Brienzersee, Thuner and Bielersee lakes, 24 hours a day, 365 days a year.

“Water level regulation must protect people from flooding and prevent damage – ideally in an economically justifiable way,” said Dr Bernhard Wehren, head of maritime regulation at AWA. “Some of our important control operations are particularly time-critical, but until recently, we relied on dataloggers that only sent the different measurements we require every few hours or so. Now, thanks to the new state-of-the-art technology we have implemented, this happens in real time. It is therefore very important that the data communications technology supports this by reliably meeting all the challenges and requirements of our unique mission-critical communications infrastructure.”

Modernising facilities
To help provide the most reliable flood protection, AWA decided to modernise its water regulation facilities for the lakes, encompassing four historic locks, the large Port of Bruggweir and accompanying hydropower plant, and a flood relief tunnel. Due to the increasing demand for the availability of more data, AWA also decided to upgrade all the measurement stations with state-of-the-art technology. The measurement stations play a crucial role in regulating water levels in the lakes.

When developing a plan to modernise the equipment, great attention was paid to both operational safety and system redundancy. There was a need to address the obsolete electrical engineering at Port of Brugg. This would include the conversion of all existing drives and the renewal of the energy supply, a large part of the cabling and the control and monitoring elements for the five weirs. Regulation and control technology also needed attention. Not only was there a need for redundancy in the event of a device failure or a line interruption, but also in case of communication disruptions, such as interruptions to the internet connection.

BKW Energie AG was appointed as the technical service provider and after a thorough review of suitable data communications technology companies, they chose Westermo to provide its robust networking solutions for the project.

Fast communication performance
“Crucial to the selection of Westermo was that their products met our high standards and requirements for the project. This included fast communication performance, multiple routing ports per device, high MTBF periods, extended temperature ranges and very low power consumption,” said Rénald Marmet, project engineer at BKW Energie. “Another factor was the operation and parameterisation of the networking hardware via the WeOS operating system. Also, the extremely efficient and time-saving update capability provided by the WeConfig network management software, which enables the central configuration and management of all Westermo devices.”

The main control network incorporates the AWA control centre in the capital, Berne,and further control centres at the water locks, Thun and Interlaken, each with one SCADA server and redundant controller. The control centres connect to 29 substations (measuring points). Eight SCADA clients access these servers. There is also a SCADA server located in the hydropower plant, providing BKW employees with access. The hydropower plant part is monitored by the BKW control centre in Mühleberg.

Westermo networking technology allows all data to be transferred in real-time between the participating sites. Should an emergency arise, this enables those responsible to take the appropriate measures immediately to ensure the best possible protection against flooding. Also, maintenance and software updates for all the installed Westermo networking devices can be performed easily and quickly with just a few mouse clicks.

In total, Westermo provided thirty of its RFIR-227 Industrial Routing Switches, twenty-seven VDSL Routers, twenty-fiveMRD-4554G Mobile Routers, thirty-five Lynx 210-F2G Managed Ethernet Switches with Routing Capability, thirty-six L110-F2G Industrial Layer -2 Ethernet Switches, and over eighty 100 Mbps and 1 Gbps SFP fibre optic transceivers via multimode and single-mode fibre for distances up to 80km.

Greater network redundancy
The three control centres all have two firewall routers connecting them to the internet providers and enabling them to receive or set up the IPsec and OpenVPN tunnels. There are also two redundant Siemens Simatic S7-400controllers installed in a demilitarized zone (DMZ) and a WinCC SCADA server connected to the local network. The AWA SCADA station has the same design, but without the control functionality.

BKW took care not only to create network redundancy, but also to set up redundant routes to the internet providers. The VDSL routers use the service provider Swisscom, and the MRD-455 4G mobile radio routers are equipped with SIM-cards from Sunrise. The heart of the main network – the three control centres and the AWA control centre- are linked by IPsec-VPN Tunnels and Generic Routing Encapsulation(GRE) and form the automation backbone via Open Shortest Path First(OSPF) technology.

The result of this is that even should there be simultaneous connection failure to an internet provider in one location and the other provider at another station, or the total failure of one provider, communication between all centres, the connected remote stations and the remote access by BKW or AWA is still possible.

For increased safety, the external zones are segmented further. The service technicians can connect to the control centres through an OpenVPN tunnel and have access to all measuring stations on the network.

There are two different types of measuring stations. The high availability station consists of two completely separate networks. Each PLC is installed ‘behind’ a Westermo Lynx 210 device, which acts as a firewall and establishes the connection to the control centre via an OpenVPN tunnel. The redundant internet access is provided either via a VDSL router, which is connected to Swisscom, or a MRD-455 with Sunrise as the provider. A ‘standard’ station has only one PLC with a Lynx 210 acting as a firewall router and building the VPN tunnels in parallel via the two internet routers.

Security requirements
As well as network redundancy, security was also part of the requirements to guarantee high communication availability. The network implemented by BKW and Westermo provides the necessary security in accordance with recommendations found in the BDEW whitepaper and IEC-62443 standard. The outstations not only form their own zone, but other areas are also segmented where necessary. The network for the SCADA servers in the control centres is also decoupled from the backbone using two VRRP routers.

The flood defence system now has one of the most modern data communication systems in Switzerland. Explaining why this is so important to AWA, Dr Bernhard Wehren said: “Protection against flooding must be guaranteed at all times. Depending on the meteorological or hydrological situation, the availability of the required measured values is critical. Because access to the measuring stations in the extensive regions of the canton is generally very time-consuming, network device failures and communication interruption must be kept to a minimum. It is therefore extremely important that all components of our communication systems meet the highest standards, offer extreme reliability and can be upgraded to meet new requirements.”

“We were able to simplify processes, make them secure, redundant and transparent for the engineering department via VPN connections. This contributes significantly to the simple, safe and efficient maintenance of the system,” Rénald Marmet said. “Thanks to the extensive cooperation with Westermo network engineers, we were able to create the ideal solution that meets all requirements and was delivered on time. Westermo’s reliable networking technologies have given AWA and BKW the opportunity to build individual data communication solutions for critical industrial applications, while providing scalable, future-proof applications. The solution also offers all involved a high degree of investment security.”

#Switzerland. @Westermo @bkw #Environment #PAuto

Treating wastewater as a resource.

27/09/2016
A number of British landfill operators are turning wastewater into a resource by utilising OTT monitoring and control systems to manage the irrigation of Willow crops (for renewable energy generation) with pre-treated effluent.

Background
Leachate from landfill sites represents a significant potential environmental liability, extending long into the future after a landfill site has closed. Conventional treatment and disposal options involve biological treatment and consented discharge to either the wastewater treatment network or to the environment. Alternatively, effluent may be collected by tanker for treatment and disposal off-site. However, to improve sustainability and broaden the treatment options, work initiated in the 1990s developed an approach that sought to use effluent as a source of nutrients and water for a Short Rotation Coppice (SRC) crop planted upon the restored landfill.

Willows fed on wastewater!

Willows fed on wastewater!

Following the success of early trials, the Environment Agency published a Regulatory Position Statement in 2008, which said: ‘SRC as part of a landfill leachate treatment process… is a technique (that) can be an environmentally acceptable option if managed appropriately.’

Early systems were operated and managed manually but with the addition of OTT sensors, telemetry and control systems, the process was automated to optimise irrigation and maximise both the disposal of effluent and biomass yield.

Willow SRC has become increasingly popular in environmental restoration work, providing a cost-effective material for stabilisation and reclamation of disturbed landscapes, bioremediation and biomass production.

SRC involves the planting of high yielding varieties of willow at a high density, typically 15,000 plants per hectare. The crop can be expected to last for around 30 years, with harvesting taking place every 3-5 years, and yields varying from 8 to 18 tonnes of dry woodchip per hectare per year. Willow grows quickly and has a particularly high demand for water, so it is ideal for the disposal of large volumes of treated effluent. In addition, the high planting density results in the development of a dense root hair system; effectively creating a biological filter for the treatment of organic compounds and the absorption of nutrients and some heavy metals. Soil fauna help to break down the effluents applied to the crop and soil particles control the availability of nutrients to the willow.

Monitoring and control
In early schemes, irrigation was managed manually on a timed basis with irrigation quantities based on external estimates of evapotranspiration. However, increased levels of monitoring and control are now possible. OTT’s Matthew Ellison explains: “The key objective is to supply the crop with an optimised amount of water, whilst minimising the requirement for staff on site. Too much irrigation would cause run-off and too little would under-utilise the treated effluent and result in poor growth conditions which would affect yield and potentially threaten the crop.

Soil moisture sensors

Soil moisture sensors

“An on-site weather station feeds local weather data to the system which uses crop data to predict evapotranspiration that is used to determine irrigation rates. Soil moisture sensors then check that soil moisture status is correct. Other sensors monitor the performance of the system; checking irrigation feed reservoir level, in-pipe pressure and there are sensors to check flow rates from the drip-feed irrigation. This communication capability is made possible with OTT’s Adcon Telemetry radio network.

“Our latest monitoring and control equipment automates the management of the system for unattended operation and staff are only required by exception. This means that the system is able to operate autonomously, delivering regular data reports, and staff are notified by email or text if alarm conditions occur.”

Emphasising the advantages of controlling the entire network, Matthew adds: “This system facilitates the ability to control and synchronise the main pump, and to open and close the valves at each irrigation zone.”

The latest OTT monitoring and control systems include:

  1. Soil moisture sensors
  2. Irrigation tank level sensors
  3. Irrigation function check sensors
  4. Pipe valves and pressure sensors
  5. Automatic weather station (to calculate local evapotranspiration)
  6. Radio telemetry
  7. ADCON Gateway and PC running addVANTAGE software
  8. Internet connectivity for remote log in

Summary
Looking back over a number of SRC projects, Stephen Farrow one of the instigators of this approach in the UK, and now an Independent Consultant says: “When viewed practically, environmentally and commercially, experience has demonstrated the viability of the overall approach.

“It is also clear that process optimisation with relatively low cost investment in OTT’s monitoring and control equipment has significantly added to the support functionality in terms of both operation and regulatory management.’’

OTT’s Matthew Ellison agrees, adding: “SRC clearly offers a sustainable option for effluent treatment, with highly positive effects on carbon footprint and biodiversity.

“In addition to the environmental benefits, process automation has significantly reduced labour requirements and helped to demonstrate compliance with the site-specific requirements of the Environment Agency.”


It’s the little things that trip you up!

22/01/2016
By Brian Booth, VP of the Water Treatment Innovation Platform, NCH Europe

There’s a lot of chemistry, physics and maths involved in perfecting your water treatment solution. To make sure you successfully treat and protect your system you need to get the equilibrium right, and this relies on balancing all the appropriate equations – even the little things you may not give much thought to. Missing something like half life out of your planning can have serious negative implications for your water treatment, especially when it comes to complying with regulations such as those for Legionella control.

When dosing your water cooling system with biocides it’s imperative that the concentration is correct and that it remains at a continuous concentration for a suitable period of time. While this sounds simple, it’s easy to forget that any bleed water required to compensate for water that may evaporate out of a system, will take a portion of your biocide with it.

Say you put 10 tonnes of make-up water into your system, and every hour 1 tonne runs off as bleed water, this will determine the half life for your system. So for example, let’s imagine the chemical you are using to meet the Government’s Health and Safety Executive (HSE) Legionella control L8 Code of Practice needs to remain at a concentration of 100 parts per million (ppm) for three hours to be successful.

If you just dose 100ppm and walk away, the concentration will gradually fall from the time of dosing and will not remain high enough for long enough as the bleed water will take a portion away with it. This will result in a failure to meet the regulation, making you negligent and leaving you liable.

This is why it’s vital to be aware of half life so that you can increase the dose of your biocide accordingly. Do you know how many hours it would take to reduce a 100ppm dose to 50ppm in your water cooling system?

Although it’s hard to be 100 per cent accurate, you can work out your half life with this simple equation:

 

Half_Life_hours.jpg

If you know your biocide is going to take three hours to be effective, but the half life of your system is one hour you’re going to have to make some adjustments to maintain appropriate concentration. For instance, using our above example of legionella control biocide, to stay at a minimum of 100ppm for long enough you’ll need to dose to 800ppm.

A bit of predictive mathematics goes a long way towards protecting your water system and keeping you compliant. Don’t let a little thing like half life leave you vulnerable to negligence claims – do the maths first!

Half_life_in_water_treatment


Pressure Transducer Delivers water level monitoring in emergency tank shower!

24/11/2014

Applied Measurements were recently contacted by spill control and containment manufacturer Empteezy, to provide a sensor to be used within an emergency tank shower.  The emergency tank shower is ideal for use in locations where a constant water supply and adequate water pressure cannot be guaranteed.

Emergency_showerThe Challenge 
To ensure the emergency tank shower is able to provide a flow of 75.7ltrs per minute of water for 15 minutes, fulfilling the ANSI Z358.1 regulations for emergency tank showers.

The Problem 
Once a gravity fed shower is switched on and the water level within the tank drops, both the water pressure and the flow rate at the shower head decreases.  In order to achieve the flow rate of 75.7ltrs per minute of water for the full 15 minutes, the emergency tank shower needs to contain a minimum of 2000ltrs of water within the tank.

The Solution
Applied Measurements provided Empteezy with a Pi600 series pressure transducer.  The pressure transducer was connected and calibrated to the digital readout scale on the front of the shower, giving an accurate reading of the litres of water remaining in the tank.  When the water level falls below the minimum safety level, a signal is sent to the sounder strobe alarm on the front of the shower.  This signal has a dual function. Firstly, alerting safety personnel that the water level has dropped below the minimum, notifying them to refill the shower to achieve the required flow rate and water pressure. Secondly, that the shower has been operated and an injured employee may need assistance.

Pi600The Pi600 Series of Pressure Transducers
The Pi600 series of pressure sensors are designed for the measurement of gas and liquid pressure across a wide range of general purpose and industrial applications such as hydraulics, medical, research and development, meteorology and food processing.  Constructed from stainless steel with a ceramic diaphragm and viton ‘O’ ring seal as standard, they are designed to be extremely rugged, yet compact in design.

Key Features Include:

  • Ranges 0-50mbar up to 0-700bar
  • Wide Variety of Outputs: mV/ Volts / mA
  • Can be Offered Calibrated in Metres Water Gauge
  • Sealed to IP65 (plug & socket) or IP66/68 (Cable)
  • Accuracy: <±0.25%/FS (0.1% option)
  • Gauge or Absolute Versions
  • Various Pressure Port Options (G1/4” male as standard)
  • Excellent Chemical and Abrasion Resistance
  • Rugged Construction
  • Full Customisation Possible

These pressure transducers come in pressure ranges of 0-50mbar and 0-700bar in absolute or gauge versions, with a wide choice of electrical output signals from its ASIC-based amplifier circuit.  These outputs include, 4-20mA, 0-5Vdc & 0-10Vdc, 1-6Vdc and 10mV/V, as well as a ratiometric 0.5-4.5Vdc signal that requires a 5Vdc supply to suit most data loggers.  The Pi600 series of pressure transducers can also be supplied with any of our wide range of instrumentation to give you a complete calibrated system.

In addition, the series can be completely customised to suit your application including; custom process connections, alternate case and ‘O’ ring material for applications where aggressive media is present, and higher IP ratings for more challenging environments.

The Pi600 series of pressure transducers have proved vital in Empteezy’s emergency tank shower units, enabling engineers to guarantee the water pressure and flow rate of the units.  We are always looking for new and exciting challenges so contact our technical sales team today on +44 (0) 118 981 7339 or info@appmeas.co.uk to discuss your application.


Remotely operated pneumatic water pumping system keeps Guernsey dry!

11/10/2014

Festo’s CPX platform – complete automation solution

Much like the mainland Britain, Guernsey has been ravaged by the forces of nature this year. But thanks to a remotely controlled, pneumatically operated pumping station that was completed last year, one area of the island has escaped damage from the resulting floods.

On February 3rd this year (2014) Guernsey faced one of its wettest and windiest days in recent memory. Heavy rain fell throughout much of the day and by the evening Guernsey Airport had recorded 32.5mm – more than an inch – of rainfall, flooding many of the island’s major roads, making several impassable and causing widespread disruptions.

Both local radio stations were forced off air as the FM transmitter was flooded, with TV signals being unavailable for part of the night. According to Guernsey Police more than 60 roads were flooded – which outpaced the number of closed signs available. Sandbags also ran short as authorities scrambled to contain the worst of the weather.

Guernsey_water

But thanks to improvements at the Marais Stream pumping station one area of the island emerged virtually unscathed from the onslaught. The pumping station, situated off les Banques not far from the capital of Guernsey, St Peter Port, is part of a network of facilities that form Guernsey Water’s infrastructure for the catchment, storage and transfer of raw water for the production of the island’s drinking water.

“Without a doubt we would have suffered big issues this winter with the heavy rainfall if we hadn’t undertaken the work there,” Andy Benstead, Water Production Manager, at Guernsey Water says. “I can guarantee that there would have been problems if we hadn’t upgraded it.

“We don’t actually have rivers in Guernsey they are all classified as streams; the Marais Stream has a fair catchment area and it includes a bank and an insurance company, and without this work they would have been flooded.”

 The work at the pumping station was an upgrade; the whole infrastructure was changed apart from an old tank that remained. “There were two reasons for the upgrade, part age and part because the area had suffered from a flooding problem,” Benstead adds. “The equipment is much bigger, more reliable, easier to control and we can now pump up to 1000 litres a second.”

Marais Stream pumping station was originally built in 1938 and required an upgrade to allow an increased volume of water to be collected and delivered to the nearby water treatment works with less going to waste.

Geomarine, a local civil engineering contractor, was contracted by Guernsey Water to carry out these improvement works as part of on-going works on the island’s infrastructure. Before the project was started all that was on site was a holding tank and pump house.

Marais Stream collects the run-off water from the local area and this is fed via the three inlet penstocks   through fine screens that remove debris that would damage the pumps in the pumping station. The water is then pumped either into the treatment works or, in the case of heavy rainfall such as earlier this year, can be diverted and discharged straight into the sea.

The entire system is run by Festo’s CPX remotely operated control system

The entire system is run by Festo’s CPX remotely operated control system

The pumping station is the first on the Island which could be considered ‘multifunctional’, as it incorporates three vital elements. Firstly, raw water (rainfall) is caught and transferred into Longue Hougue reservoir for conversion into drinking water. Secondly, stream water is used to maintain the cleanliness of the screens at the new Belle Greve Wastewater Treatment Centre. Finally, the new pumping station enables excess water to be pumped out to sea, which might otherwise overload the capacity of the Barker’s Quarry Reservoir and lead to localised flooding.

“Festo supplied three pneumatically operated penstocks, driven by linear actuators, to isolate the flow; these were located in the incoming channel,” Tony Gillard, Business Development Manager at Festo explains. “DNC cylinders with rod clamps are used to control the raising and lowering of the penstocks. These distribute the incoming water into the storage basins. From the storage basins, the water is distributed to various parts of the site by butterfly valves operated by pneumatic quarter-turn actuators.”

The entire system is run by Festo’s CPX remotely operated control system. The site itself is unmanned and is controlled via the SCADA system from the Guernsey Water Offices based five miles away. “The CPX platform is a complete automation solution that integrates a wide choice of pneumatic and electrical, analogue and digital I/O,” Gillard explains. “CPX systems configured for specific requirements are delivered pre-built, tested and ready for installation, enabling system integrators to meet tight deadlines and budgets. For additional flexibility, the CPX platform can operate as either a self-contained industrial PLC, or as a local unit on a Fieldbus or Industrial Ethernet-based distributed system. In addition, a wide choice of I/O and connector modules makes interfacing to process sensors and actuators easy.

“Remote operation is becoming more common; with pneumatic control you have the functionality to remotely operate the system,” Gillard adds.

Unusually for the water treatment sector is the selection of pneumatically controlled valves rather than electric. “On Great Britain it is more usual to have electric actuators but the advantages of pneumatics are beginning to sway the market,” Gillard says. “In most other applications, such as petro chemical and industrial applications, pneumatics are the preferred solution, but for some reason in water treatment and sewage plants electric actuation is still predominant for now.”

Pneumatic automation presents an extremely reliable alternative to electrical automation systems and reduces the costs of investment, installation and operation compared with conventional electrical installations.”

Guernsey Water has gone down the path of changing electric actuators to pneumatic and is reaping the benefits. Pneumatic control delivers energy saving, ease of installation, safety and reliability, because of less moving parts, as well as being faster to operate and easier to control.