Anti-Corrosion Treatment by Blygold Australia

Protection Against Corrision in the HVAC Environment

Corrosion is one of the most avoidable but common reasons for declining performance and efficiency of air conditioning systems.

Ways to prevent corrosion and protect assets against early decline are easy to implement. Please read the following article and follow the link to the Blygold Australia website.

As most facility managers are aware, operating your HVAC (Heating, Ventilation, Air Conditioning) equipment accounts for 40-70% of your energy bill.

As a result many engineers work hard to improve their facility and make it more energy efficient and economical. This happens not only out of concern about the quality of the facility, but also out of the necessity to work within budgets while providing optimal service delivery.

Nowadays we see that the number of services provided everywhere expand rapidly. Public and staff have high expectations regarding the delivery of these services as well as the facilities that they are delivered in and governments, investors, developers and owners expect quick results and return on investment.

One aspect of creating quality facilities is implementing short term plans that create medium and long term results with positive budget implications. This brings us to areas like energy efficiency and sustainability.

A number of important observations are relevant in regards to creating these efficiencies:

  1. It makes most sense to target high energy use areas of operations
  2. It makes most sense to target those areas that haven’t been targeted yet
  3. HVAC will account for 40 to 70% of your energy bill
  4. HVAC is a major capital expense in your facility
  5. HVAC is one of the most basic but important facility services.

So what is it that we can do in Air Conditioning that can substantially decrease facility costs and / or increase efficiency? One of the core problems facing many facility managers is the degradation of the HVAC equipment and the subsequent inefficiencies such as increased maintenance and energy costs.

The specifications that make our coatings unique are:

An important part of this degradation is due to corrosion in the coils of the chillers. 3 important things to remember:

  1. Corrosion will occur in every AC chiller coil
  2. Corrosion is the most important factor in the decrease of efficiency of your chiller
  3. Corrosion is also one of the easiest to tackle and avoid.

Chiller Coils

Most chiller coils are built out of aluminium fins around copper tubes. Copper and aluminium aren’t compatible metals and copper being the superior metal will slowly degrade the aluminium fin, make it brittle and thin and cause so-called ‘galvanic corrosion’.

This image shows Galvanic corrosion in existing coil. The copper tubes corrode the aluminium fins until they fall apart and disintegrate.

HVAC Coil Corrosion

Another concern is environmental and industrial corrosion, caused by for example car exhaust gasses, industrial pollution, salt in the air etc. Due to this corrosion the fins will reduce their heat transfer / conductivity very significantly, clog up with dirt and salt adhesion, become brittle and will literally fall apart, sometimes in a matter of years.

The clogged-up coils will have greatly reduced airflow,therefore, they will loose efficiency and a generate a substantially higher energy bill to generate the same outcome.

This image shows corroded coils due to salt and pollution.

So in doubling that lifespan of your coils you have in effect saved yourself hundreds of thousands of dollars in premature capital investments. There are a great number of anti-corrosion treatments available on the market, some more effective than others.

Your options in your facility will be as follows:

    Do nothing and hope for the best. This is not a good option in the short, medium or longer term as corrosion will continue to ravage your chiller coils and the inefficiencies in your chillers can reach levels of increased energy use of 40 to 70%.

    The image to the right is a coil tested by the BSRIA Institute, an independent research house in the UK. The coil is virtually destroyed after only 4000 hours of salt spray (six months).

    Treat your existing HVAC units on site with an effective anti-corrosion coating. One of the most successful coatings that can be applied on site is Blygold’s PoluAl XT coating. It is a very effective way to protect your chiller coils from further corrosion as the coating is a spray-on application, a so-called ‘post coat application'. This coating can be applied in situ, has a metal pigmentation so the conductivity of your coils is maintained, is UV resistant and boasts a salt and acid test resistance of 4000 hours.

    Ensure that all new coils are treated before installation on your site. This way you get the best and most affordable option. However, this is only relevant for new units and will not be available to existing units.

    On-site treatment of existing chiller coils by Blygold staff. This treatment will include; thorough cleaning of the coil, drying, application of anti-corrosion coating from both sides of the coils, covering the fins, tubes and headers.

    Pre-coat and Post-coat Anti-corrosion Coatings

    There are the so-called ‘pre-coat’ options, which is a coating applied to big sheets of aluminium during the production process. These sheets are then cut in strips the width of the coil fins and the holes for the tubes are punched in. Then the coil is put together. Blue fin and Gold fin are the most commonly known of these coatings.

    The image to the right is a Gold fin pre-coated coil tested by the BSRIA Institute in the UK. The coil is corroding significantly after 1000 hours of salt spray, i.e. a month and a half. Corrosion is most evident around the tubes where there is bare aluminium.

    The biggest advantage of a pre-coat process is that it is fast, automated and cheap. The biggest drawback is that it is not very effective as it will have bare aluminium where the sheets have been cut and the holes been punched. This is exactly around the tubes and the edges of the fins, where normally your corrosion will occur. Other coatings might dip or submerge the coils. Advantage is that it is cheaper, but also that the coating thickness is uneven, most coatings are not UV resistant and the coating can’t be applied or maintained on site.

    The most effective option is to apply the earlier mentioned ‘post-coating’ on the new coils too, which means that the coating is applied after the coil has been fully assembled. The coating is applied with a spray-on application and the coating will not only cover the fins, but also the connection between the fins and the tubes and the tubes themselves as well as the headers. This way you’ll get a fully protected coil that can stop the corrosion from occurring.

    The image to the right is Spray-on application of coating on new coil. This coating is: Blygold polyurethane based coating with metal pigmentation, is only 25 microns thick once dry is flexible and UV resistant, is salt and acid spray resistance of 4000 hours, doubles lifespan of the coils and saves up to 20% energy.

    You might now think, what about the newest coils that are made out of aluminium only? Surely they don’t need protection? Well, we have to disagree here as these MCHX aluminium coils (MCHX stands for Multi Channel Heat Exchanger) obviously don’t have the galvanic corrosion as discussed earlier, but by being exposed to air the aluminium will oxidize and therefore will become thinner and more brittle over time. An effective coating here can save you very substantial money too.

    As you see, we can confidently state that an anti-corrosion coating can be a very worthwhile initiative as it can actually realize very substantial savings for you. As always: the devil is in the detail, so make sure you are well informed before making any decisions.

    A lot of problems in the performance of your chillers can be avoided and with the right support you can optimise the functioning of your AC installation for a long time to come. Most brands will offer the factory applied Bluefin coating, depending on the specifications of the project. However, the Blygold coatings are also supported by all major HVAC brands and do not influence the warranty on their units.

    All companies warrant their coating for12 months, Blygold warranty is valid for 5 years and can be extended on an annual basis.

    A lot of coatings have a limited lifespan where the post coatings normally last the lifespan of the coils and don’t have to be re-applied.

    Benefits of Blygold Treatment

    • save up to 20% on energy use
    • double the lifespan of the heat exchangers
    • ensure the highest level of performance of heat exchangers
    • increase reliability of the climate control system
    • provide cleaner air to staff, visitors and other users
    • in general our services earn themselves back within 12 months.

    Specifications for Application of Blygold Anti-Corrosion Coating

    • Polyurethane based coating, not epoxy
    • Salt and Acid test resistant for 4000 hours
    • Is a post-coating, i.e. applied after full assembly of the coil
    • Has metal pigmentation to maintain conductivity, no drop in efficiency
    • Is UV resistant and flexible
    • Only 25 to 30 micron thick once dry
    • Coating can be applied and maintained on-site as well as in our workshops
    • Full penetration due to spray-on application, no dipping
    • Has standard warranty of 5 years, which can be extended on an annual basis (conditions apply)
    • Is approved by EcoSpecifier
    • Member of the GBCA


    Ecospecifier    Green Building Council Australia Member