1. Corrosion on HVAC equipment
Causes & Remedies
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corrosion on HVAC

2. 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
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corrosion on HVAC

3. 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).
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corrosion on HVAC

4. Decreasing Capacity Q-AIR Condenser Capacity (m3/h) (kW) 84.400 258
-50%
-36%
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5. Increasing power consumption
Case Study
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corrosion on HVAC

6. Shortening Life Expectancy
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corrosion on HVAC

7. 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

8. 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
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corrosion on HVAC

9. Environmental Corrosion
Types of Corrosion
Galvanic Corrosion
Cause
Effect
Visual Appearance
Environmental Corrosion
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corrosion on HVAC

10. 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

11. 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)
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corrosion on HVAC

12. Visual Appearance of Galvanic Corrosion
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corrosion on HVAC

13. 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

14. 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

15. 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.
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corrosion on HVAC

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

17. On Copper Visual Appearance of Environmental Corrosion
Different colors shows different corrosion process
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corrosion on HVAC

18. 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

19. 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.
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corrosion on HVAC

20. Quality standards Neutral Salt Spray Test
Marine by ASTM B-117 / ISO 9227 / SS DIN This salt spray test shows no defects after 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 City life causes acid rain, Thermoguard shows no defects after hours. Reflecting nine years of exposure to an urban climate.
Kesternich Test
DIN / SFW 2,0S Hundred and twenty cycles or ten years of heavy polluted sulfuric air have been a proven success for Thermoguard.
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corrosion on HVAC

21. Quality standards Abrasion Resistance Test
ASTM D 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 Metal expand and shrink by fluctuations in temperature. Flexibility is measured by Erichsen tests.
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22. Mass loss in acetic salt spray test
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23. 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
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corrosion on HVAC

24. 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)
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corrosion on HVAC

25. Pre-Coating
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26. 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
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corrosion on HVAC

27. 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!
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corrosion on HVAC

28. 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%)
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corrosion on HVAC

29. 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
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corrosion on HVAC

30. 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
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corrosion on HVAC

31. 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.
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corrosion on HVAC

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

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

34. 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
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corrosion on HVAC

35. 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
Hours
< 1000 Hours
Salt Spray ASTM G85
+3000 Hours
< Hours
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corrosion on HVAC

36. 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.
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corrosion on HVAC

37. Anti-Microbial
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corrosion on HVAC

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

39. 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)
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corrosion on HVAC

40. Anti-Microbial
After
Before
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41. Power consumption of an unprotected system vs. post- coating
CO2 Emission Reduction
Power consumption of an unprotected system vs. post- coating
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corrosion on HVAC

42. 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)
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corrosion on HVAC

43. Organization and Application Facilities
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corrosion on HVAC

44. 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