Full-scale collector being tested under artificial sun.

Hydro has carried out some of the toughest high-temperature corrosion tests ever performed, together with Solartechnik Prüfung Forschung (SPF) in Switzerland.

These tests confirm that aluminium tubes in Hydro’s HyLife™ Solar alloy are fit for use in solar thermal systems and that they can be expected to last for 20 years, as long as the following design criteria are met:

• Aluminium tubes should only be used in the collector circuit and for closed systems that are hermetically sealed.
• Aluminium tubes should only be used in systems that include a glycol with an inhibitor in the heat transfer fluid. The amount of glycol in the mixture shall follow the producer’s guidelines. The following products may be used with Hydro’s HyLife™ Solar aluminium tubes:
                  • Antifrogen® SOL HT Conc. (*) from Clariant International Ltd
                  • Antifrogen® SOL HT from Clariant International Ltd
                  • Coracon Sol 5 (*) from Aqua Concept GmbH
                  • Coracon Sol 5F from Aqua Concept GmbH
                  • ®PEKASOLar 100 (*) from pro KÜHLSOLE GmbH 
                  • ®PEKASOLar 50 from pro KÜHLSOLE GmbH
                  • Solarliquid L (*) from Staub & Co Chemiehandels GmbH
                  • Solarliquid L gebrauchsfertig from Staub & Co Chemiehandels GmbH
                  • Tyfocor ® L Concentrate (*) from Tyforop GmbH
                  • Tyfocor ® L from Tyforop GmbH

(*) concentrated products. Antifrogen® SOL HT Conc., Coracon Sol 5 and Solarliquid L to be diluted with a max. amount of 50% vol. distilled water. ®PEKASOLar 50 to be diluted with a max. amount of 55% distilled water, Tyfocor ® L Concentrate to be diluted with a max. amount of 60% vol. distilled water.

• The aluminium tubes should only be brazed with an AlSi based filler material that does not contain zinc.
• Any fittings to the absorber/collector, either on the collector or the connecting lines, should be in aluminium or stainless steel. It is important not to use brass fittings which contain zinc.
• Any fittings, or other connections, between aluminium tubes and other materials, should be externally covered by a permeation tight and sealed heat shrink cover or similar protection.
• It is recommended to only use a non-corrosive flux without chlorides when brazing. Corrosive fluxes require careful post-brazing cleaning of the brazed area in order to prevent it from corrosion.

To read the entire test report, download by clicking here:
HyLife™ Solar high temperature corrosion test results