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Industrial water quality monitoring for cooling towers a success

Hydro Flow is an Australian-owned company, principally staffed by a team of engineers and scientists, that is dedicated to providing world-class water treatment programs and solutions to all market sectors. The company provides technical and project services, manufactures and supplies treatment chemicals, and installs and maintains dosing and filtration equipment.

Established in 1996, Hydro Flow is an Australian-owned company, principally staffed by a team of engineers and scientists, that is dedicated to providing world-class water treatment programs and solutions to all market sectors. The company provides technical and project services, manufactures and supplies treatment chemicals, and installs and maintains dosing and filtration equipment.
One of the principal services offered by Hydro Flow is the management of cooling towers, including water treatment, microbiological testing and corrosion monitoring. Chief among these is the monitoring necessary to eliminate the risk of bacterial growth in cooling tower water, particularly Legionella bacteria.

Legionella bacteria occur naturally within soil and water in the environment, and can enter a cooling tower system through water dispersion, where it can rapidly reproduce in the warm and moist environment it provides, particularly in the presence of nutrients and sunlight. It can then escape the system within aerosols and travel significant distances to potentially enter a person’s respiratory system.

The importance of water quality

In Australia, legislation regarding microbiological testing for cooling towers varies between state and territory jurisdictions, but In Victoria, where Hydro Flow’s head office is located, water samples must be taken to test for Legionella (from monthly to quarterly) and Heterotrophic Colony Count (at least monthly), and the water tested by a NATA-accredited laboratory.
While laboratory testing may be a legislated requirement, the quality of the water can be controlled (and the bacterial risk mitigated) by dosing the water with antibacterial agents.

Commonly used oxidising biocides such as chlorine and bromine can kill bacteria relatively quickly, while concentrations can be monitored relatively easily. However, oxidising biocides tend to be associated with corrosion, so over-dosing needs to be avoided if possible.

Reducing maintenance with automated water monitoring

To date Hydro Flow has been monitoring cooling tower dosage with a number of other monitoring methods, measuring dosing levels and making adjustments as required. To minimise time on-site and to lower maintenance and calibration costs, the company decided to take advantage of its more than 20-year relationship with Bürkert and investigate the idea of automated water quality monitoring, while upgrading its current chlorine and pH measurement technology.

Hydro Flow’s aim was to lower maintenance and calibration workload so that its technicians can be more efficient while reducing the amount of unnecessary maintenance expenses and consumables being charged to the end-user.

Automated water quality monitoring solution benefits Hydro Flow

To help achieve the goal of automated water quality testing, Bürkert offered up its Type 8905 online water quality monitoring system, combined with a Type MZ20 automatic cleaning system.

“This was an agreement between Hydro Flow and Bürkert for the benefit of both parties,” said John Kennedy, National Water Field Segment Manager for Bürkert. “Bürkert offered Hydro Flow their latest in water quality management technology for their cooling tower application, to see how the benefits could be established in industrial water industries.

“For Hydro Flow, if the trial of the water quality monitoring system was a success, then they could also benefit from the advantages of using this technology, particularly with their other clients with a larger infrastructure, such as museums, galleries, hospitals, stadiums and inner-city spaces.”

All parameters analysed by a single unit

Typically used for drinking water quality applications, the Type 8905 Online Analysis System is a modular system for monitoring all important water parameters on one platform – pH, chlorine, chlorine dioxide, conductivity, ORP, turbidity, iron and temperature.

The Efficient Device Integration Platform (EDIP) allows a high degree of flexibility by using modularity in the hardware as well as in the software of the system. For maintenance, sensors can be removed without tools, while the remaining sensors continue to measure. The Type 8905 is available as a compact system in one housing (supporting up to six measurements), as well as a customised system supporting up to 60 measurements.

Hydro Flow decided to use the system at a site in the Melbourne CBD. The Type MZ20 automatic cleaning system was also installed, automatically cleaning the fluidic channels and the sensor surfaces in the connected sensor cubes – eliminating another element of maintenance.

The combined system also offers traditional analog outputs and fieldbus connectivity, with remote access, allowing the system to be monitored remotely.

More accuracy, more savings

In testing the system, a benefit that was sought by Hydro Flow was to lower the monthly cost of consumables – not just in dosing chemicals, but also in maintaining the measurement technology. While inaccurate dosing can mean a greater consumption of chlorine, and also a greater corrosion risk, the previous measuring equipment such as pH and chlorine sensors also utilise reference chemicals and require regular calibration.

“With existing sensors, Hydro Flow needed to replace chlorine membranes every 6-10 months and electrolyte every three months, and the system would take up to 24 hours to stabilise,” mentioned Adam Kielbaska, Water Treatment Engineer at Hydro Flow.

“More accurate sensors and less drift means getting the dosing rate right – insufficient chlorine means higher risk, while too much means more corrosion"

“Customers feel more confident in a system that works more efficiently, for the safety and reliability of customers or tenants in and around their buildings,” he emphasised.

With the Bürkert sensors, the KCl cartridge on the pH sensor need only be replaced annually and the chlorine sensor needs its MEMS sensor chip replaced on average once every two to three years – with only around five minutes labour each time. And since the Bürkert sensor cubes cannot dry out, they can be calibrated and left ‘on the shelf’ as a spare, ready to install as needed, without on-site calibration.

Confidence in Bürkert's solution

After more than two years, the system is still working and providing a low-maintenance solution within the Melbourne CBD cooling tower. Mathew French, Area Manager - Projects summed up the solution, saying, “During the pandemic in 2020 there were limitations to site access during lockdown, however we had confidence in Bürkert’s solution to continue the accurate water quality monitoring for the test site.”

Type 8905

Online Analysis System

Type 8905
  • For analysis applications for drinking water and fresh water in industrial processes
  • Modular sensor and electronic system: - up to 6 measurements in one housing - up to 30 analysis sensor cubes in one Bürkert system bus (büS)
  • Prepared for fielbus connectivity and remote access
  • MEMS technologies allows minimal footprint and minimum sample water demand

Type MZ20

Cleaning System

Type MZ20
  • Automatic cleaning for type MSxx sensor cubes
  • Protection against clogging in the system and inside the sensor cubes for long time accurate measurements
  • Different cleaning solutions for organic and inorganic contamination
  • Application specific programmable cleaning cycle

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