Remote monitoring points the way to corrosion prevention

Corrosion of pipework and components in water based heating and cooling systems nearly always results in costly repairs and unwelcome disruption, especially where a large office block, hospital or district heating scheme is concerned. When failures occur in the low temperature hot water (LTHW) or chilled water (CHW) systems the tendency is to investigate the failed component and possibly much later to call in specialist corrosion consultants (Such as Midland Corrosion Services) to find the root cause of the problems and recommend a solution. That is all well and good, but it is a bit like closing the stable door after the horse has bolted, especially when one considers that the problems could have been predicted and therefore avoided if proper measurements of key parameters had been made from the point of installation and commissioning.

One of the basic problems has been that building maintenance / facilities management companies have relied on periodic water sampling to check on the health of the systems. Not only does this only give a partial picture (water composition is only one aspect that needs to be considered), it is a snap shot view taken at best once per month. The industry has been slow to seize on the opportunity that continuous monitoring presents; namely; monitoring and recording of all key parameters, 24×7.

By using a combination of high quality reliable sensors and data loggers, all key indicators of system problems can now be continuously monitored remotely from MCS’s main office, with alarms set if critical levels are exceeded. In addition, MCS are able to provide regular reports on the health of your heating or chilled water systems and recommend actions, if necessary. Parameters that can be monitoring include:

Dissolved oxygen: Even moderate level can give rise to corrosion of metals
Pressure: positive pressures need to be maintained at all times throughout the system to prevent air entering the system
Make-up water intake: flow on the make-up line may be indicative of a leak in the system
Conductivity: A change in the conductivity suggests that inhibitor levels are not being maintained
Galvanic current: This gives a good indication of general corrosion rates of steel
Crevice corrosion monitor (patent pending): this gives a good indication of localised corrosion rates esp. in crevices and under debris
Temperature: can check that heated water is circulating as required

Figure 3 - Sensor response to changing conditions in LTHW system — Figure 3 – Sensor response to changing conditions in LTHW system

Interpretation of the data is paramount if proper diagnosis is to be made and experienced corrosion consultancies such as MCS are well placed to offer a fully managed continuous monitoring corrosion service.

For more details contact Steve Munn at Midland Corrosion Services on +44 (0)1629 733162 or email smunn@midlandcorrosion.co.uk