Why does chlorine dioxide dosing go wrong in the building services sector?

Let’s ask ourselves why chlorine dioxide dosing has received this negative press…

In our opinion, it is a combination of issues ranging from the blatantly obvious to the hidden, even misunderstood aspects of practices that have been developed and adopted over the years within the industry. As mentioned, the use of chlorine dioxide can be a reliable, safe and efficient method for water disinfection when used correctly.

'The obvious'

Poorly practiced installation and maintenance, in addition to operator error through lack of training, are where safety goes wrong from the onset.

Incidents which can occur from this include accidental spillages, over and under dosing of chemical reagents, corrosion and unnecessary DBPs to name a few.

'The hidden'

Generator design failures often cause ‘hidden’ issues.

These malfunctions can fail to protect the correct reaction chemistry due to inadequate metering accuracy, often lowering biocidal efficacy. Poor calibration, tampering with reagent pump settings and vulnerability in operation due to poor quality materials can also cause failures prior to PPM visits.

Other hidden issues include chemical reagent drums running unnoticed and empty, as well as maintenance companies offering service contracts for equipment which they have little expertise dealing with.

Following this, the generator slowly falls into disrepair and performs poorly often without the knowledge of the operator.

'The misunderstood'

The use of redox (reduction-oxidation) in downstream monitoring was adopted many years ago to try and limit the risk of over and under dosing, in combination with pulsed water meters.

Redox can elevate due to several factors, these can include:

• Interference through fluctuations in background free-chlorine residuals and water balance
• Inability to detect quantitative ClO2 residuals for minimum and maximum thresholds to be controlled
• Not maintaining, cleaning and replacing redox electrodes frequently
• A high acid dosing ratio

Amperometric/potentiostatic residual ClO2 measurement is implemented for downstream monitoring, adopted to help improve the limitations of earlier redox control systems.

However, this then misses the point, as these analysers were often installed to protect over and under dosing events due to poor equipment design, rather than just biocidal compliance. Poor installation and/or maintenance of the analyser causes another major vulnerability to over and under ClO2 dosing events occurring, which can be hazardous.

Industry specifications based on old practices and outdated designs, unclear industry guidance and real lack of understanding on what compliance means, are leading issues of misunderstanding.

Many choose the correct equipment installation scheme but misunderstand that WRAS only covers the components or product in contact with potable water, not the installation. The entire installation must be in accordance with local water supplier byelaws and the drinking water supply to remain wholesome at all times within the building.

Always remember, prevention is better than cure!

Protect the operator, secure the chemical reaction efficacy, build a robust product that is both simple to install, maintain and operate. This sounds easy, so why is this not happening enough in practice then?

Using the right chlorine dosing technology is key…

Technology plays a great part as we know in the advancement of improving and influencing most things we see and do every day in life. The same is no different in this case.

Take for instance the chloriDOS® iOX®, a completely unique and patented chlorine dioxide generation and dosing technology, manufactured and distributed globally by Gaffey Technical Services and their network of approved distributors.

British-built chloriDOS iOX® chlorine dioxide systems can provide a safe, reliable in-situ source of chlorine for a variety of industries and sectors, ranging from swimming pools and spas, to food processing lines and large water treatment plants.

• Offers inherently safe operation of chemical transfer and chlorine dioxide reaction under vacuum.
• Secures chemical reaction efficacy through precise volumetric measurement of the chemical blending and chlorine dioxide dilution process, all of which is calibrated for the life of the unit.
• Very few working parts to replace and constructed out of high quality PVDF/PTFE/FPM materials exposed to aggressive chemicals.
• Allows simple installation design restoring confidence and enabling dependency on the robust concept of a pulsed water meter delivering the correct ClO2 dose every time.
• Use a potentiostatic ClO2 analyser where necessary downstream to assist with monitoring/trending and not control, except for threshold limits/alerts.

  There is absolutely no reason for chlorine dioxide to be regarded as unsafe and should produce the excellent results expected. However, the industry needs the right companies, technicians, products and technologies to make it happen. Otherwise, nothing is going to change anytime soon regardless of having great technology available.

  If you would like to find out more about the benefits of chloriDOS iOX® chlorine generation systems, contact Gaffey Technical Services today or give us a call on 01254 350180.