To achieve these aims, a mass flow meter and control valve combination will increase process quality and efficiency. However, it’s also important to ensure optimal integration and specification within the process infrastructure to achieve the best performance and control across a water treatment application.

Across all chemical or gas dosing requirements for water treatment processes, technology specification is vital for accurate measurement and control. Prior to selecting the flow metering and control hardware, the first step is to ensure that the pipework is optimised for the application. Process application engineers commonly oversize pipework with the goal of reducing pressure drops across the system, as well as offering the flexibility of upscaling capacity at a later date. However, oversized pipe diameters and inappropriate configurations can cause inaccuracies that impact the quality of the process as a whole.

Flow measurement of liquids & gases is essential for determining the volumes of additive that need to be dispensed; maintaining accurate flow readings is important for the whole process. However, an oversized pipe typically means low velocity flow, which generally causes inaccuracies in flow measurement, because it creates an uneven or transitional flow profile characteristic across the sensor.

This creates a fluctuating flow reading that causes a corresponding variable output, with a knock-on effect to additional equipment such as pumps and valves. In liquid flow applications, 1m/sec is generally the optimal “out of the box” factory-calibrated flow velocity for most flow measuring technologies, because of its stable flow profile for reliable measurement. Even for entry-level budget devices right through to more complex advanced flow measuring technologies, manufacturers will usually state that accuracy is improved when measurement is taken at around 1m/sec.

For designers and engineers, this increase in velocity can often be achieved just by reducing the pipe diameter. Even a single standardised line size reduction can have a big impact on improving the accuracy of flow sensor measurement. However, if the existing line size is maintained, users risk velocities that are lower than the minimum capability of the measurement technology.

Oversizing the pipe will also increase the wear on a valve, particularly its seals, through the hunting effect. A fluctuating input means that the control valve opens and closes at a frequent and uncontrolled rate in an attempt to identify the correct position and maintain the target flow point. This can also impact pump operation, leading to a similar acceleration in lifetime wear, increasing costs in maintenance, hardware and through downtime.

The position of the flow meter within the system is also crucial to ensure accurate readings. Bends in pipework in close proximity to the sensor, as well as obstructions, such as additional components, can also cause turbulent, slow or uneven flow characteristics such as eddies. These factors can create the same challenges as an oversized pipe.

In gas applications, changes in velocities before the metering system will impact on the measurement stability. This will create an unstable flow profile that is not representative of factory-calibrated conditions.

Operators and commissioning engineers can often dampen a sensor’s output in an attempt to stabilise the control loop, but this is only masking the accuracy issue. The process will not be as accurate as designing and installing the optimal line size or location and these factors should be addressed at outset.

Adding a modulating control valve to the system can also help to increase dosing accuracy. Controlling pressure and/or flow, a control valve provides responsive control that improves the accuracy and repeatability of the process. It provides precise control trimming and can also regulate multiple channels from a single source.

Ideally, a control valve establishes a linear increase between the Kv value, the amount of flow at a given valve position with a pressure loss of 1 bar, to stroke opening. This control curve ratio changes based on the type of control valve used, as well as the position of the designed valve. The flow control partner will be able to specify the ideal technology, as well as assist in accurately sizing the valve, including calculation of the inlet and changing outlet pressures. Dynamic, multipoint performance data can help to specify an accurate and predictable valve, optimised for the application’s characteristics and requirements.

Increased application accuracy and repeatability will not only improve process performance and end-product quality, but it can also help to reduce process costs by optimising the volume of the chemical being dosed. Improvement in metering and control typically means using a lower volume of chemicals with no loss in quality.

In a recent example, a Bürkert customer involved in wastewater treatment had inadequate monitoring over sludge thickness that caused fluctuations in the polymers introduced for the dewatering process. This resulted in excessive chemical use and poor sludge thickness from the process. Introducing a mass flow meter and control valve could have enabled close correlation between sludge level and polymer dosing, reducing process costs in raw materials.

While combining sizing techniques and technology specification can improve process optimisation, integrating the required technologies is also important to ensure reliability. An integrated flow control portfolio enables repeatable performance, communications compatibility and ultimately, ensures system uptime and throughput.

Bürkert is ideally positioned to achieve these requirements to optimise existing as well as new water treatment processes.

Continual, online monitoring provides the greatest reliability in measurement, and new sensors from Bürkert offer a cost-effective solution to enhance water quality and reduce the time required for testing.

To ensure public health, the quality of the water we consume, whether straight out of the tap, from bottled spring water, or from processed drinks and foods producers, has to achieve safe limits of its compositional elements. One group of compounds present in water that must fall within safe limits includes nitrates (NO_3-), and while naturally occurring in vegetables and the human body, excessive levels present a risk to health. With up to 50 parts per million (ppm) considered safe for children, and adults with immune system vulnerabilities, the UK and EU have set this figure as a maximum level within water for consumption. In addition to nitrates, drinking water must also be disinfected to leave only safe levels of bacteria.

Critical for the food and beverage industry, taste is also impacted by nitrate levels and organic impurities. These compounds and organic matter also have to be closely monitored to ensure end-product quality for other sectors that rely on pure water, such as pharmaceutical production. Even industries that only use water to enable a process have to ensure that nitrate levels don’t adversely affect the end result, for example in textile and paper manufacture, where colour can be affected.

The most common source of nitrates in water is from agricultural production, with nitrates from fertiliser and manure seeping into the ground, running into the feed of boreholes, streams, natural springs, and reservoirs. Whether capitalising on the benefits of a local source for provenance and taste, like for bottled spring water and beer, or using a private source to remove the higher cost of supply from the utilities, organisations with their own water supply take on the responsibility of testing for nitrates and organic impurities. Even for water utility companies, in water source areas susceptible to higher nitrate concentrations, they also need to be able to check quickly and accurately to ascertain whether more precise nitrate testing is required.

For most organisations, the financially viable and typical nitrates test method is a periodic spot check, with a sample taken at intervals, rather than continuously. Dependent on the end users’ capabilities and facilities, samples can be tested with their own analysers, or they can be sent to a lab for analysis. To monitor organic impurity bacteria levels, the five-day jar test is the typical check for pollution of a biological oxygen demand (BOD), with a two-to-three-hour test to check chemical oxygen demand (COD) organic. Both tests measure a sample from just a single moment of time. Whether an individual sample is tested by the end user or sent to a lab, environmental conditions don’t stay the same for long and a changing situation, such as overnight rain, could quickly increase the level of nitrates and impurities. Any water produced between test results has the potential to be wasted if parameters are found to have been exceeded, therefore reducing this time period to almost zero saves any wastage.

To increase the frequency and accuracy of measuring nitrates and organic impurities in water, giving a more reliable overall picture of the levels, Bürkert has added two new sensor probes to its online, real time water analysis system. The Type MS09 nitrate sensor provides constant, high accuracy measurement of nitrate with precision between 0-50 mg/l. Utilising a xenon flash lamp to measure nitrate by UV optical absorption, organic and turbidity compensation removes negative influences to optimise measurement reliability.

In addition, the MS08 SAC254 sensor, utilising spectral absorption coefficient (SAC) UV light at 254 nm, provides optical absorption measurement of organic impurities with reliable LED technology. Providing continual monitoring of dissolved organic compounds, including BOD and COD matter, the sensor also measures TOC (total organic carbon) with monitoring of activated carbon filters to determine saturation levels.

Continual, automated monitoring removes the resources required for periodic testing as well as the delay awaiting lab-based test results. This technique also safeguards against the potential of high volume scrappage. The sensors are also quick to install and configure, featuring plug-and-play operation with Bürkert’s online water analysis system via the included fieldbus gateway. With no moving parts, the sensors are also maintenance-free and optical measurement ensures long-life operation.

Bürkert’s online analysis system, available in the Type 8905 compact modular platform and the Type 8906 cabinet format, monitors all important water parameters on one platform, now adding nitrates and organic impurities to the measurement of pH, chlorine/chlorine dioxide, conductivity, redox potential, turbidity, and temperature. Based on highly reliable CANbus, the prevalent protocol within the automotive sector, Bürkert’s EDIP network enables fast integration with the PLC and Ethernet-based network of choice.

From the outset, the system requires accurate sizing and, combined with precise control enabled by automation, this will ensure product quality as well as a cost-effective process in the long term.

Accuracy is a key requirement for feeding gas in a water treatment process. This ranges from applications that require neutralisation of pH levels with carbon dioxide, removing iron or manganese to create process water, or oxygenating wastewater to assist the bacterial breakdown process. Imprecise gas insertion can result in reduced process performance and a lower quality end-product. Moreover, excess gas use can significantly increase process costs over the long term.

Achieving an optimal gas feed requires accurate and responsive control, and this starts with accurate sizing of the metering and control system. The fundamental requirement for measurement of gases present in water is a precise calculation of inlet pressure, referred to as P1, outlet pressure, referred to as P2, as well as the flow rate. Together, these values are used to accurately size the system’s mass flow meter (MFM) and control valves.

Within a mass flow controller, the gas flows through a control valve orifice with a smaller diameter than the main pipe. This creates a pressure drop as the flow rate becomes proportional to the downstream outlet pressure, following Bernoulli’s principle that states an increasing fluid speed creates a corresponding decrease in static pressure. This explains the importance of clarifying either the P1 (inlet pressure) or P2 (outlet pressure) to determine the potential flow rate.

Confirming the accuracy of these values is as important for optimising an existing system as it is for specifying a new application. It’s not unusual for a customer site to use a mass flow meter or controller that hasn’t been correctly sized at the outset and is therefore inaccurate and unable to achieve the required flow rate. Usually, the site’s engineers know the inlet feed pressure, though rarely the outlet figure, but a flow control specialist will be able to assist with accurate sizing and required flow rate calculation.

As well as pressure and flow rate, it’s also vital to understand the precise gas volume to achieve the desired results for a given application. With this understood, a flow control partner can also support the calibration process to confirm accuracy of the sensors specific to the gases involved.

Assuming the ability to accurately measure gas flow, precisely controlling the feed is the next step. If gas pressure, flow rate and temperature are constant, fixed manual control of gas flow can be sufficient. However, this situation is a rare occurrence. Taking a CO2 infusion application, for example, as the gas is fed in and volume of CO2 in the host container decreases, inlet pressure also decreases, impacting flow rate accordingly. Opening the mass flow controllers orifice will increase flow rate, but maintaining accuracy across this control process requires automation to achieve the required precision.

Even more basic applications with a lower dependence on gas feed accuracy require human knowledge of mechanical valve control. However, this places greater reliance and time requirements for on-site operation by engineers, as opposed to time saving, automated control.

Managing flow also depends on the changing gas levels in the water. Controlling pH, for example, can require precise adjustment based on feedback from a probe. Accurate and repeatable results rely on a rapid control response according to the changing conditions, which can only be achieved without impacting throughput by an automated process.

Automation also enables faster and more accurate documentation, removing the time requirement and potential for inaccuracies in reporting. Applications in food and beverage, for example, demand frequent data recording with evidence of accuracy from calibration records to meet national standards. While an automated system ensures a robust process, it also reduces costs in the long term, compared to human data logging.

While an experienced systems integrator might only require an accurate mass flow meter to achieve these benefits, OEMs and end-users can benefit from assistance in sizing, as well as a full package of flow system components including metering, larger control valves and sensors. Bürkert’s engineers can provide a comprehensive system that is tailored to specific requirements and designed with all the components supplied in-house to ensure compatibility and optimum performance.

This service will not only achieve an accurate gas control system to meet the application’s conditions, but it will also reduce the long term costs in raw materials, human resources and maintenance.

There are numerous parameters that need to be monitored and accuracy as well as repeatability are crucial for operators’ confidence. Bürkert’s compact, modular water quality analysis solution offers an automated process that delivers precision monitoring for a wide variety of applications.

Water is a vital resource, not only for basic living, but also in industrial settings, where it is used for manufacturing, power generation and throughout the food and beverage market. As such, the quality of the water can directly affect product quality, so regular sampling and testing is essential to ensure any remedial actions are taken promptly.

Water quality monitoring can take many forms, from the most basic manual sampling and testing to large-scale automated systems, but in every case, accuracy and repeatability are crucial. Improvements can be achieved by increasing the frequency of testing, calibrating sensors regularly and benchmarking results.

Bürkert’s Type 8905 Online Water Analysis System offers a modular format for analysing water quality, allowing operators to select exactly the parameters they need for each application. Capable of measuring turbidity, iron, chlorine, conductivity, oxidation reduction potential (ORP) and pH, using the same base unit, the 8905 offers simple operation and precision measurement.

A single 8905 unit can handle a multitude of different sample lines, which makes it ideal for monitoring a variety of processes, such as filtration, and identifying any anomalies. For simple operation, each sensor cube can be removed for maintenance without affecting the analysis process for the other parameters, minimising downtime.

Of particular interest is the MS06 iron sensor, which is compatible with any type 8905 system. It features three bottled fluids, reagent, calibrating and cleaning solutions. Beneath every bottle is a load cell, which measures the volume of liquid in each container and these values can be sent to the central control point in the same way as the water quality data.

Testing for iron content can present several challenges, especially when it is only present in small quantities. Manual tests can deliver variable results, especially when they are carried out by different staff. However, the MS06 iron sensor can complete a test every 30 minutes and provide accurate results down to 0.03 ppm by volume.

Furthermore, whereas some iron analysis equipment can require extensive maintenance interventions to keep it operational, the 8905 has almost no need for external support.

The Type 8905, equipped with the MS06 iron sensor, offers the opportunity to monitor water quality automatically in both open and closed loop applications and ensure chemical dosing and filtration processes are operating as required. The accuracy and repeatability of this monitoring solution can help to identify process failings, minimise operational costs and offer peace of mind for the quality of the wider production process.

The pharmaceutical industry is embracing new technology that can reduce costs and simplify installation. At the production site of a multinational healthcare diagnostic test manufacturer, Bürkert’s FLOWave has proven to offer the best solution for measuring the flow of ultrapure water. In fact, a recent expansion project has placed a repeat order for the versatile flowmeter, having provided four years of faultless service in the initial installation.

Pharmaceutical manufacturing requires many stringent specifications to be met by all the components used in a production facility. Not least among these are hygiene and accuracy, but when dealing with ultrapure water, the choices for a precision flowmeter can be limited. The main reason is that this liquid has very low conductivity, which rules out mag-flow meters, and until recently, there was only one viable option for a flowmeter.

Using Surface Acoustic Wave (SAW) technology, Bürkert has developed a flowmeter in which none of the components are in direct contact with the fluid and which causes no restriction to flow. Furthermore, the internal surface of the tube can be manufactured to the same surface finish as the rest of the pipeline, meaning that in terms of hygiene, cleaning and flow conditions, there is no difference to any other piece of straight pipe within the process.

The FLOWave also solves many of the issues associated with some high-end flowmeters, such as system vibration in the plant, magnetic and electrical effects as well as the conductivity of the liquid – none of these factors have any effect on the accuracy or reliability of the flow measurements.

One of the early adoptions of the FLOWave in a pharmaceutical setting was in the healthcare diagnostics manufacturing plant, where it was used to measure ultrapure water volumes being used by a set of laboratories. The project included the installation of two FLOWaves as part of a new process build, which benefitted from the compact, precision-made and cost-effective solution.

The recent Covid pandemic has led to increased demand for laboratory diagnostic products and the decision to install a second production line that will manufacture a key component used in Covid diagnostic testing. Part of this project was awarded to KJB Water & Process Engineering, which has been responsible for the overall design of the ultrapure water system.

Within each laboratory, there are take-off points for ultrapure water, which is supplied by a ring-main. In order to ensure sufficient volumes of ultrapure water, the flowmeters are installed on the supply and return legs of the ring main; the calculated difference in flows enables the ultrapure water production system to match demand.

Dr Corby Lee, Technical Consultant at KJB Water & Process Engineering, put together the supporting evidence, with support from Bürkert, to show that the FLOWave would meet all the required specifications and be more cost effective. This demonstrated that the innovative solution could provide the required data in a hygienic setting without the drawbacks associated with more traditional instruments.

Dr Lee explains: “Now, having selected the Bürkert product for flow measurement four years previous, the latest project to install a second production line will include two more FLOWave components. Since the initial project, the customer has had no issues with the performance of the flowmeters and we were confident this latest installation would offer the same reliability.”

The features of FLOWave continue to lead the market, even against more recent developments to reduce the cost of the more traditional instruments, which were considered as part of the component analysis for the project. Thanks to Bürkert’s involvement in the project as well as excellent lead times for all the parts necessary for the installation, the FLOWave met all the project requirements and was selected again.

Dr Lee concludes: “In terms of installation, the process is significantly less complicated when using a FLOWave device as it can be mounted in any orientation and its compact design makes it easy to integrate into the overall design of the plant. Furthermore, the connectivity makes the control integration very easy and with Bürkert’s support we were able to meet the tight delivery deadlines that were set for this project.”

The trial generated accurate, reliable results for detecting trace-level impurities and chlorine with Bürkert’s 8905 analysis system and sensors. The results of the six-month trial by an environmental monitoring services company have provided confidence in the repeated accuracy of the data, now enabling investigation of wider plant automation.

Bürkert’s client was tasked to run a water analysis trial at a gas power plant in Ireland. Steam, generated from ultra-purified water, is required to drive the plant’s turbines. Water fed from a semi-covered reservoir passes through a treatment plant featuring a reverse osmosis (RO) system and an electric deionization (EDI) process, which create the required ultra-purified water. Water conductivity from the process has to be accurately measured and reduced to approximately 15 µS and the RO system is tasked with the removal of impurities, which can deteriorate the EDI over time. Impurities penetrating the RO system can also cause stress corrosion cracking in the turbine blades.

The environmental services company was required to report on the water treatment plant’s conductivity as well as levels of chlorine, pH, ORP and turbidity. The plant’s existing analysis equipment didn’t provide sufficient data, and measurement clarity as well as repeatable accuracy were essential. Irregular power demand also meant periods of low flow, which impacted stability of measurement. Specialising in reliable online environmental monitoring, the company selected Bürkert to provide the sensors and water analysis capability as a result of the company’s expertise in rapid, accurate and reliable measurement.

A full suite of Bürkert 8905 Online Analysis System units for monitoring water parameters, combined with Type MS sensor cubes, each suited to monitor a specific characteristic, were installed into a compact panel. The trial monitored the feed into the RO system and while it was originally designed to run for three months, as a result of the Covid pandemic, the sensors were left in place for six months.

The challenge of the reservoir’s low flow was a result of its oversized construction. Designed for a maximum capacity of 50 tonnes of water per hour to support hours of peak power generation, the plant can process as little as 20 tonnes per day when on standby. Typical analytical sensors on a one-inch process line require 2-3,000 litres per hour, whereas Bürkert’s 8905 system, even with five sensors, requires just 30 litres per hour. Even when a continuous pump is required to fulfil the sensors’ minimum flow requirement, the Bürkert system provides significant reduction in wastage and cost.

Throughout the six-month period, the system ran without deviation, not requiring recalibration or inspection, which demonstrated its reliability. This was a crucial requirement for the water monitoring company and also the power plant operator, giving confidence for uninterrupted service and low maintenance requirements.

Crucially, the accuracy and sensitivity of the 8905 system showed chlorine trace not previously identified. Long term, trace levels of chlorine can degrade the RO membranes and ultimately allow the unwanted passage of chlorine through to the EDI, which it can also damage. Furthermore, the customer wanted to avoid any flow of chlorine back into the river system. A carbon filter can now be used upstream of the RO to prevent the inbound flow of chlorine.

For detection accuracy, Bürkert’s 8905 water analysis system and chlorine sensor has a t90 time, the duration that it takes the sensor to measure 90% of the chlorine concentration, of less than 30 seconds, whereas typical industry standards for chlorine sensors have a t90 time from 60 to 180 seconds.

The fast reaction time also means that the 8905 sensor is unaffected by polarization, whereby a sensor measuring zero chlorine for long periods of time can take several hours to react and measure with reliability when small amounts of chlorine are reintroduced. Typical sensors can therefore be unable to measure trace chlorine levels, which can pass through the system before they are able to react. Instead, Bürkert’s 8905 sensor is able to accurately and reliably measure chlorine even at µg/l trace level.

Faster reaction is a result of the chlorine sensor design, which features only a single membrane compared to a typical chlorine sensor which incorporates a membrane pair surrounding an electrolyte buffer. The single membrane of the 8905’s chlorine sensor means that the ions buffer through reduced resistance before chlorine trace is detected by the sensor, creating the faster response rate.

The accuracy of the Type 8905’s additional sensors also identified new data that would be useful to the plant, including pH levels up to pH12, which can be used to pursue further improvements in performance and reliability across the water treatment plant. The sensors also detected a caustic solution used as part of the cleaning process, the results of which will be used to assess the long term impact to the RO system.

Cost was also reduced in system installation. The 8905 system can be installed into a single compact panel, approximately one meter square, as opposed to utilising several larger boards, complete with transmitters. This reduces wiring costs and installation time, as well as footprint. The potential for Ethernet connectivity for plant automation will also reduce the cost of sensor outputs and increase the ease of system integration. The system can be operated by the seven-inch touch display or remotely using Bürkert’s Communicator PC tool.

The results of the trial have identified accurate, repeatable and reliable readings across the analytics, which have identified potential for a more effective water treatment system. These results can then be utilised to deliver improvements across the plant for better reliability and reduced downtime.