FEATURE HVAC
ASTM STANDARDS ENSURE fluids don’t corrode HVAC systems
time is needed for maintenance, minimising business downtime and the need to replace expensive capital equipment. This is especially important for industries where production processes need to remain operational or when an optimum temperature is needed to preserve product quality and safety.
Andrew Murray, Senior Manager at Kilfrost’s Speciality Fluids Division, describes the ASTM D1384-05 corrosion test standard, the impact of heat transfer fluids on the longevity of HVAC systems and the benefits of inhibited glycols
D
espite the wide spread use of heating, ventilation and air
conditioning (HVAC) systems not all companies are paying sufficient attention to the composition or quality of the heat transfer fluids deployed. If sourced or used incorrectly, heat transfer fluid can become the most expensive aspect of an HVAC system, despite the relatively low initial cost to the customer. A key consideration, and one that is all too often overlooked, is the corrosion caused by the heat transfer fluid. Many heat transfer fluids are glycol- based that, when diluted with water to achieve the required frost protection, can become corrosive. Bacterial growth and scaling within the system can also result from using hard and/or inferior water. As the industry recognises the
challenges of system corrosion, an international test created by the American Society for Testing and Materials (ASTM), known as the ASTM D1384-05 corrosion test standard, is playing an increasingly important role. The ASTM standard is carried out in
laboratory conditions where specified pieces of metals that are commonly used
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in HVAC systems, including aluminium, iron, steel, brass, solder and copper, are weighed then immersed in an inhibited glycol/water mixture which is aerated to simulate in-situ conditions at 88oC. At the end of the four week test, the pieces of metal are weighed again and analysed for signs of corrosion. In order to pass, the mass change in the metals before and after the test must not exceed stipulated levels. Despite the existence of the ASTM standard, it does remain voluntary and there is still a lack of understanding in the HVAC industry. However, some heat transfer fluid manufacturers such as Kilfrost are choosing to adhere to the ASTM standard to give customers greater confidence in our products. Any fluid can claim to contain corrosion inhibitors, but without the presence of a test standard, the extent of protection is hard to gauge.
SO WHAT CAN BE DONE TO PREVENT CORROSION WITHIN HVAC SYSTEMS? Using a less corrosive heat transfer fluid – such as an inhibited glycol mixed with water of a sufficient quality - enables the cooling system to last longer and less
Careful maintenance of an HVAC system can ensure optimsed performance, running cost efficiency and prolong the life of the system
SYSTEM MAINTENANCE Maintenance regimes should also be assessed to ensure HVAC systems are kept in good condition. During servicing, fluids should be checked periodically for pressure and the presence of any foreign bodies which may indicate the breaking down of the fluid. In addition, the various conditions under which fluids are transferred, stored, heated and applied can all have an impact on the fluid’s performance. Regular quality checks should be performed in order to ensure that fluids are in a satisfactory condition for use all year round. It is also important to combine regular maintenance checks with an examination of the glycol content within the system in order to maintain sufficient frost protection. Finally, there is a growing focus on the
environmental benefits of glycol inhibitors with corn-derived inhibited glycol-based heat transfer fluids providing sustainable, biodegradable options to the HVAC industry. Many of these types of fluid also have low toxicity levels, making them ideally suited to applications such as food and beverage processing and manufacturing. To summarise, the ASTM corrosion test
standard offers a credible way for companies to ensure the fluid their HVAC system uses will not shorten the life expectancy of the asset. One such fluid is inhibited glycols that, when mixed with good quality water can overcome the challenge of system corrosion and, alongside a rigorous maintenance regime, can reduce business downtime and the need to replace equipment. Happy end users are those who experience time and cost savings due to the quality of the systems in use.
Kilfrost
www.kilfrost.com 01434 321 500
Enter 204 / ENERGYMANAGEMENT
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