Corrosion on HVAC equipment Causes & Remedies November 2008 corrosion on HVAC

Effects of corrosion in HVAC system Decreasing the capacity of HVAC system Increasing the power consumption of HVAC system Shortening the life expectancy of HVAC system Increasing the emission of CO2 November 2008 corrosion on HVAC

By loss of bondage between copper tube and aluminum fin. Decreasing Capacity By loss of bondage between copper tube and aluminum fin. By corrosion of the fins (reduced heat transfer area). By pollution on the fins (reduced air flow). November 2008 corrosion on HVAC

Decreasing Capacity Q-AIR Condenser Capacity (m3/h) (kW) 84.400 258 84.400 258 75.960 241 67.250 222 59.080 202 50.640 183 42.200 162 25.320 111 -50% -36% November 2008 corrosion on HVAC

Increasing power consumption Case Study November 2008 corrosion on HVAC

Shortening Life Expectancy November 2008 corrosion on HVAC

Fuel + Oxygen  CO2 + Water Increasing CO2 emission Fuel + Oxygen  CO2 + Water An increase of power consumption leads to more fuel combustion. More fuel combustion leads to more CO2 emission. November 2008 corrosion on HVAC

What is corrosion? Chemical reaction of a metal and a non-metal, which produces a chemical compound. Corrosion affects all types of metals, even corrosive resistant metals, over time and under certain conditions November 2008 corrosion on HVAC

Environmental Corrosion Types of Corrosion Galvanic Corrosion Cause Effect Visual Appearance Environmental Corrosion November 2008 corrosion on HVAC

Cause of Galvanic Corrosion Two dissimilar metals (CU + Al) Electrolyte (f.e. humidity) If any of these factors is not present, galvanic corrosion will not occur November 2008 corrosion on HVAC

Effects of Galvanic Corrosion Galvanic Corrosion of the unprotected coil begins at the bi- metallic coupling between the copper tube (more noble material) and the aluminum fins (less noble material) The result leads to dissolving of the less noble material (fin) November 2008 corrosion on HVAC

Visual Appearance of Galvanic Corrosion November 2008 corrosion on HVAC

Cause of Environmental Corrosion Environmental Corrosion is the degradation of the metal, caused by a reaction with the environment, such as oxidation and chemical attack of the metal surface November 2008 corrosion on HVAC

Cause of Environmental Corrosion Environmental Corrosion can be caused by different types of environment: Marine NaCl Industrial SOx NOx Marine/Industrial NaCl SOx NOx Urban SOx NOx Rural H2S NHx NOx November 2008 corrosion on HVAC

Effect of Environmental Corrosion The effect of the formation of a non-protective layer on the material surface. Unprotected metal will continue to react with the contaminant and corrode. The fins will often become very brittle. November 2008 corrosion on HVAC

On Aluminum Visual Appearance of Environmental Corrosion November 2008 corrosion on HVAC

On Copper Visual Appearance of Environmental Corrosion Different colors shows different corrosion process November 2008 corrosion on HVAC

On Copper Visual Appearance of Environmental Corrosion November 2008 Contaminant Chem. symbols Type of Industry Source of Potential color of corrosion Sulphur Oxides SO2 SO3 *Pulp, Paper & Lumber Plants *Fuel Burning Power Generation *Diesel/Gasoline Engine Operation Process Emissions Products of Combustion Black Blue Nitrogen NOx *Incineration Facilities Green Chlorine & Chlorides Cl2 Clx *Cleaning Agent Processing Water Treatment Facilities *Salt Mining/Processing Swimming Pool Agents Water Disinfections Process by Products Brownish Yellow (non-hydrated) Green (hydrated) Ammonia & Ammonia Salts NH3 NH4 *Chemical Industries *Fertilizer Manufacturers *Agriculture Waste Digestion Animal Waste & Fertilizers Hydrogen Sulfide H2S Water Waste Treatment Facilities Pulp, Paper & Lumber Plants Sludge Processing November 2008 corrosion on HVAC

Types of Corrosion Protection Method Cost Protection area Influence on Heat Transfer Environmental Cost Treatment Remedy Cu/Cu Stainless steel High All Better than Cu + Al Lower than Cu + Al Low Difficult to manufacture. Must be done in factory. No, must replace coil! Galvanizing No influence. Difficult to treat. Must be done in factory. Pre-coating Fins only Slight lower than original fins Little higher Easy. Same process as normal heat exchanger. Post Coating Middle With high Conductivity paints, could reduce the contact resistance between fins and tubes. Easy Could be done in factory or in field. Yes, repair in fields is possible. November 2008 corrosion on HVAC

Quality standards Neutral Salt Spray Test Marine by ASTM B-117 / ISO 9227 / SS DIN 50021 This salt spray test shows no defects after 10.000 hours. Reflecting ten years extension of life time in real life at the sea side. Acid Salt Spray Test Urban by ASTM G-85 / ISO 9227 / ESS DIN 50021 City life causes acid rain, Thermoguard shows no defects after 3.000 hours. Reflecting nine years of exposure to an urban climate. Kesternich Test DIN 50018 / SFW 2,0S Hundred and twenty cycles or ten years of heavy polluted sulfuric air have been a proven success for Thermoguard. November 2008 corrosion on HVAC

Quality standards Abrasion Resistance Test ASTM D 4060 Desert Area. The Taber Abraser test concludes about exposure to erosive conditions like sandstorms. Thermoguard passed this test as extremely resistant to mechanical impacts. Cycle Exchange Test ISO 20340/B Because of insufficient correlation between the results of salt spray tests and results in the field, exchange tests are more reliable and used. Flexibility Test NEN-ISO 1520 C1 / DIN 53156 Metal expand and shrink by fluctuations in temperature. Flexibility is measured by Erichsen tests. November 2008 corrosion on HVAC

Mass loss in acetic salt spray test November 2008 corrosion on HVAC

Parameters effective coating Optimal layer thickness: thick enough for a good protection and thin enough to avoid pressure drop and bridging Negligible effect on heat conductivity UV resistance Minimal dirt adhesion Superior chemical resistance Flexible to cope with expansion and contraction Easy application (onsite / in workshop) Not sensitive to application conditions Repairable November 2008 corrosion on HVAC

Fins are made out of aluminum sheets. Pre-Coating Fins are made out of aluminum sheets. With a pre-coating those sheets are already protected by a coating before cutting After cutting the sheets, new unprotected surfaces are created (a louvered fin has more cutting edges) November 2008 corrosion on HVAC

Pre-Coating November 2008 corrosion on HVAC

Only protect part of fins: no protection on the cutting edges Pre-Coating Only protect part of fins: no protection on the cutting edges Al Pre-Coating Corrosion begins here! Unprotected at Cutting edges November 2008 corrosion on HVAC

Pre-coated material: epoxy Pre-Coating Pre-coated material: epoxy Epoxy bases pre-coating is not resistant to UV radiation, so not suitable for exposure to the sun. A condenser with pre-coated fins needs a roof to prevent decaying! November 2008 corrosion on HVAC

This decreases the heat transfer (about 5 to 7%) Pre-Coating With a pre-coated fin the coating forms an insulation between the copper tube and the aluminum fin. This decreases the heat transfer (about 5 to 7%) November 2008 corrosion on HVAC

No unprotected surfaces are present Post-Coating With a post-coating the coating is applied after full production of the coil. No unprotected surfaces are present All metals are protected from the environment by the post-coating The coating forms a barrier between the metals and the electrolytes. No galvanic corrosion can occur November 2008 corrosion on HVAC

Protect all the area of Coil! Post-Coating Protect all the area of Coil! Also Protect copper tubes of Coil! Al Double Protection Layers No open area of Al Fins and Copper Tubes November 2008 corrosion on HVAC

Post-Coating Post-Coating is a Poly Urethane, which gives a good resistance against UV radiation. Poly Urethanes are highly flexible to cope with expansion and contraction. Post-Coating contains aluminum pigments to increase the heat transfer through the coating. If there is a gap between the fin and the tube, this gap will be filled with the coating, due to the low viscosity. This results in: A better bonding (heat transfer) No more galvanic corrosion. November 2008 corrosion on HVAC

Minor effect on the heat transfer and air side pressure drop! Post-Coating Minor effect on the heat transfer and air side pressure drop! November 2008 corrosion on HVAC

The Post-Coating system can be applied: In the factory Before installation (years) after installation November 2008 corrosion on HVAC

High chemical resistance Post-Coating High chemical resistance Acids Alkalines Salts Aromatic Hydrocarbons Aliphatic Hydrocarbons Halogenated Hydrocarbons Ethers and Esters Alcohols Fuel and oil Softeners Ketones and Aldehydes Amines November 2008 corrosion on HVAC

Comparison Pre-Coating vs. Post-Coating Type Poly Urethane Epoxy Layer thickness 1 mil (25-30 micron) ± 0,4 mil (± 10 micron) Heat conductive Yes No Repairable Chemical resistance Excellent Poor Ph Resistance 0 to 14 3 to 11 UV Resistance Very bad Flexibility Good Color Silver, reflects heat Black/Yellow/Blue Warranty 3 year Maintainable at site Header treatment Cutting edge protection Casing Coating Cost Acceptable Low Surface Characteristics Smooth Very smooth Salt Spray ASTM B117 +10.000 Hours < 1000 Hours Salt Spray ASTM G85 +3000 Hours < 500 Hours November 2008 corrosion on HVAC

Anti-Microbial The function of an air-conditioning system is to maintain a good thermal climate and acceptable indoor air quality. Besides the corrosion problems, the units also have to deal with the growth of micro organism. November 2008 corrosion on HVAC

Anti-Microbial November 2008 corrosion on HVAC

Anti-Microbial An effective solution is applying a special designed coating that prevents growth of micro organism, such as: Bacteria Yeast Moulds Algae November 2008 corrosion on HVAC

Anti-Microbial By applying these special coatings, adhesion of dust, dirt and micro organism to the surface is avoided. Anti microbial is available for all types of coatings (heat exchanger, casing, floor) November 2008 corrosion on HVAC

Anti-Microbial After Before November 2008 corrosion on HVAC

Power consumption of an unprotected system vs. post- coating CO2 Emission Reduction Power consumption of an unprotected system vs. post- coating November 2008 corrosion on HVAC

Reduction of power consumption leads to a reduction of CO2 emission. CO2 Emission Reduction Reduction of power consumption leads to a reduction of CO2 emission. Calculation Sheet (website) Calculation Sheet (laptop) November 2008 corrosion on HVAC

Organization and Application Facilities November 2008 corrosion on HVAC

Applying any kind of Corrosion protection gives a lot of advantages. Conclusion Unprotected coils will have a limited lifetime and decreasing performances. Applying any kind of Corrosion protection gives a lot of advantages. Durability of a Post-Coating is better than a Pre-coating. November 2008 corrosion on HVAC