TREATMENTS AND FLUIDS


Why protecting yo for the environme pocket


After a 10 year study and research program by BOC and Kings College London, an air quality index has been established to reduce the high pollution within London city centre. Frank Frayling of Bronz- Glow explains how this is eff ects air conditioning units.


D id you know that NOx /NO2 and SO2 in


combination are highly corrosive to both copper and aluminium? And these are found in our air today in high quantities – both are produced by diesel vehicles.


Copper


Copper is used for heat transfer coils in air conditioners and although early chamber studies had shown that NO2


has little impact on copper


at concentrations of 1.3PPM and that hydrogen sulphide (H2


S), SO2 on copper than NOx and SO3 . Later chamber studies found that NO2 +SO2 were


synergistic and increased the observed corrosion rate of copper by 10 to 20 times than the observed rate under single gas flow conditions.


Aluminium


Aluminium is used for the fins on air conditioning units and it has been noted that the wetness of aluminium correlates with NOx


concentrations all had more impact but it could not be concluded that NOx was of any


importance in the aluminium corrosion process. In a chamber study it was shown that NO2


was synergistic with SO2 did


not significantly absorb on aluminium but, at 90% RH NO2


three times the corrosion of either pollutant alone.


It was demonstrated in another chamber study that the interaction of NO2


was complex and it


was concluded that the water acted to displace NO2


on the surface and corrosion occurred simultaneously with the absorption/displacement process.


In a real three year UK environment study if was found that a suitably coated coil can reduce the need to clean the condenser, keeping not only the corrosion at bay but also the ability to reduce the accumulation of contaminants due to the nature of its smooth surface, reducing friction and making the air passage much more efficient. Below are photographs of two separate condensers in a motorway service station type


and caused nearly


54 June 2017


www.acr-news.com


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