It is essential that DO is low in a closed system (ideally less than 0.2 mg/L). Dissolved oxygen is the main driver of corrosion as without this there is no cathodic reaction. By measuring DO we can ensure the system is air-tight and that any oxygen introduced by fresh aerated water is quickly consumed.
A closed system must maintain a positive relative pressure at all times to avoid air being sucked into the system. We monitor this at the highest point in the building using a small satellite monitoring system.
We measure water make-up volume to indicate leaks in the system or inform us on planned flushing activities
We measure temperature to ensure that the system is operating as intended.
For systems containing aluminium we check that the pH is not going above 8.5 (otherwise the passive films break down and aluminium components such as heat exchangers can start to corrode).
When biofilms form microbial influenced corrosion often occurs and this can lead to wall thinning and pin-holing in metal pipes. We are trialling a sensor that will enable us to monitor the risk of biofilm formation.
Under-dosing with chemicals can adversely affect corrosion and performance. Conversely, over-dosing wastes money and is bad for the environment. By measuring conductivity we can tell if the concentration of the water treatment products is within recommended levels.
We have developed our own sensor to monitor the currents that occur between different metals in the system and lead to serious corrosion. In plain water galvanic currents increase in proportion to dissolved oxygen. However, inhibitors when at the correct strength passivate metal surfaces and suppress galvanic currents. This sensor enables us to check that the inhibitor is doing its job effectively, even when there is some oxygen in the system.
We have developed and patented our own sensor to detect crevice corrosion, a particularly insidious form of corrosion leading to rapid pitting attack and pin-holing. It occurs in localised regions such as weld seams and under debris where a micro-environment can be formed.
‘The Hevasure monitoring service provided us with a perfect view of all the key parameters of a heating system in real time and the monthly reports were detailed and impressive’
The organization should develop processes to provide for the systematic measurement,
monitoring, analysis and evaluation of the organization’s assets, asset management system and asset management activity on a regular basis
Hevasure have been monitoring the existing LTHW system at our prestigious 155 Bishopsgate site in Central London. Not only did this reassure us that we were maintaining the system in excellent condition but the comprehensive reports provide us with hard evidence to back this up.