All Hydratech heat transfer fluids are formulated with synergistic inhibitors that neutralise the natural tendency of water to corrode, scale and foul pipe-work systems. If corrosion inhibitors are absent from aqueous based antifreeze formulations, oxidation corrosion is almost instantaneous due to dissolved oxygen retained within the water. Soon after oxidation corrosion occurs galvanic activity will develop leading to pitting corrosion.
Both oxidation and galvanic corrosion will be accelerated as the antifreeze turns acidic and bio-films form. I.E. a cycle of corrosion will result if corrosion inhibitors are omitted or allowed to deplete.
Scale deposits are a serious concern for open systems that require constant make-up with fresh water. The problem is far less of an issue for closed loop systems that are filled once or require negligible top-up. As a precaution all Hydratech formulations include polyacrylates that prevent solid particles adhering to pipe walls or other system components.
Biological contamination is a very common problem within aqueous-based cooling and heating system. Bacteria and algae will breed quickly, especially in systems that have not been properly flushed and cleansed prior to commissioning. If a biological film is allowed to establish itself within heat transfer systems then the rate of that heat transfer can be severely impinged. All Hydratech heat transfer fluids are formulated with one or more non-oxidising biocides that remain active for many months and sometimes years after initial filling.
Before reviewing the different chemical methods of preventing system corrosion, it is worth listing a few design principles that will work in conjunction with any corrosion inhibitors.
Choose metals that have reasonable resistance to the various forms of corrosion common within heating and cooling systems. As a rule of thumb steer away from the less noble metals, especially magnesium, zinc and galvanised coatings.
Design the pipework and system in a way that reduces pumping losses and keeps sharp bends to a minimum. The objective is to maintain turbulent flow within heat exchangers and laminar flow in all other pipework.
Sealed and pressurised systems are far less prone to absorb fresh oxygen in comparison to systems with open header tanks.
Include sufficient automatic vent valves that can constantly remove any air that might enter the system.
Consider a side-stream filtration system that constantly removes any corrosion by-products and debris.
Coupon corrosion rigs are not expensive and provide a good indication of internal corrosion.
- Keep the system pressure high enough to minimise vapour coming out of solution and thus prevent cavitation corrosion.
Corrosion Inhibitor formulations play a vital role in maintaining pipework systems and capital equipment. By blending together several chemicals it is often possible to achieve synergistic results - specifically where two or more chemicals work better together than in isolation. Individual manufacturers of Heat Transfer Fluids should know which formulations provide the greatest long-term protection for systems fabricated from various metals and plastics. Hydratech has extensive expertise in corrosion inhibitor technology and works with individual customers to ensure the correct fluid and inhibitor combination is selected.
Hydratech blend many different corrosion inhibitor formulations for use in cooling and heating systems. Some formulations are specifically for mixing with other antifreeze chemicals, while others can be added to 'water only' systems.
To ensure that corrosion inhibitor packages continue to provide long-term system protection, Hydratech operate the SureFlow Fluid Maintenance Program, where customers periodically send fluid samples to our laboratory for testing. Subject to the test results we will sometimes make recommendations to add additional inhibitors.