HVAC
CORROSION: THE HIDDEN SCOURGE OF CLOSED-CIRCUIT HVAC
Steven Booth from Guardian Water Treatment, part of Marlowe Environmental Services, explains the causes of corrosion in close-circuit HVAC and the important role real-time monitoring plays in keeping this hidden affliction at bay.
Corrosion is a significant problem for heating, ventilation and air conditioning (HVAC) systems, and particularly difficult to detect in the closed-circuit variety. If not nipped in the bud, corrosion leads to inefficiencies and eventual leaks, increasing the risk of downtime and the potential for costly repairs and sometimes whole system replacement - significant issues, particularly in large commercial buildings, that put FMs at risk of fines.
“With a deeper insight into the corrosion process and how it can be mitigated, site-specific water treatment programmes can be implemented that tackle the root cause of corrosion and reduce the risk of system failure and expensive repairs."
In theory, closed-circuit HVAC systems should be sealed and safe from the outside influences that cause corrosion. The reality is that even after the most thorough precommission cleaning and handover process, these systems are sometimes passed over to FMs with hidden issues that often don’t rear their head until it’s too late. Throughout a HVAC system’s life, any point where interference takes place – during routine maintenance, for example - the risk of contamination and unfavourable adjustments to the pre-defined set-up can occur. Changes in pressure, pH and temperature, for example, can all detrimentally effect operations.
The ‘invisible’ nature of these types of building services, therefore, presents significant challenges to FMs and building maintenance teams. If left unchecked, buildings are left vulnerable to downtime and the need for expensive repairs. Often the first sign of a problem is a leak, by which point major corrosion damage has occurred.
Water sampling, the traditional methods to check condition, while useful, has limitations that can miss critical signs of corrosion. The industry is now embracing more sophisticated, real-time monitoring solutions which crucially identify the conditions likely to cause corrosion before its repercussions have taken hold.
54 | TOMORROW’S FM Traditional corrosion detection vs.
advanced monitoring Traditionally, engineers relied on water sampling for corrosion detection. This method, however, only offers a limited view of a snapshot in time, often missing key indicators like dissolved oxygen which is difficult to accurately detect in a sample. Oxygen alone causes corrosion, and it is also a necessary ingredient for the survival of certain types of bacteria, some of which can lead to Microbial Induced Corrosion (MIC).
Advancements in real-time
corrosion monitoring The introduction of real-time monitoring technologies marks a significant shift in industry best practice as evidenced in updated guides BSRIA BG29 2020 and BG50 2021, which cover pre-commissioning cleaning and ongoing water treatment respectively.
The latest real-time monitoring solutions detect a range of critical parameters that signify corrosive conditions, including dissolved oxygen, pH, pressure, inhibitor levels and corrosion rates. Any event, whether planned or unplanned (such as leaks or loss of pressure), is flagged on the inbuilt charts.
Drawing on this cumulative data, FMs have the benefit of a true and accurate picture of system condition – an ideal basis to plan ongoing maintenance strategies.
These systems monitor various parameters continuously, providing an in-depth, real-time view of the system’s health. This approach not only allows for early detection of potential issues but also minimises the need for physical inspections. FMs are kept well and truly in the picture, with alerts sent direct to their inbox if critical levels are exceeded. Reports show trends during a period with recommendations to keep the water system healthy.
With a deeper insight into the corrosion process and how it can be mitigated, site-specific water treatment programmes can be implemented that tackle the root cause of corrosion and reduce the risk of system failure and expensive repairs.
As the FM sector increasingly adopts real-time monitoring as standard, we will see a generation of healthier buildings that perform better, use less energy and cost less to maintain.
www.gwtltd.com
twitter.com/TomorrowsFM
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