Art, We looked into acid corrosion issues with multiple customers who had experienced leaks in anti-freeze systems. We found that in the presence of heat and oxygen both propylene glycol and ethylene glycol break down over time to form acidic byproducts (acetic, lactic, formic, etc.), most of which are highly corrosive to the mild steel in fire sprinkler piping. You can read more about it here: http://ecscorrosion.com/wp-content/uploads/2015/09/White-Paper-Acid-Based-Corrosion-in-Antifreeze-Fire-Protection-Systems.pdf
We found acid corrosion failures in both the anti-freeze system and the wet system supplying the anti-freeze system because of problems with the check valve or backflow preventer separating the systems. It's interesting that you haven't seen any problems in the anti-freeze system yet. When you say you have drained and filled the system 6 times does that also include the anti-freeze system? If not, you should trying flushing the antifreeze and starting over with a new solution and also verify that the check valve/backflow preventer separating the systems is functioning properly. Thanks, Lucas Kirn, PE Engineered Corrosion Solutions ph: (314) 415-1387 - web: www.ecscorrosion.com<http://www.ecscorrosion.com/> From: Art Tiroly [mailto:atir...@atcofirepro.com] Sent: Wednesday, July 13, 2016 12:27 PM To: sprinklerforum@lists.firesprinkler.org Subject: Acidic Corrosion We have an issue with sprinkler water becoming acidic 5.5-6 PH. System is 6 months old. The Bellville seal corrodes and cracks resulting in drips from sprinkler. 6 sprinklers so far. City water is not acidic. Test from back flow drain shows acid 5.6. Manufacturer says it is acid water corrosion. Other tests also acidic. Some black pipe, mostly CPVC in an old Frat house System drained and filled 6 times. What can be causing low PH in a few weeks. Pictures show corrosion inside the sprinkler throat and seal. There is also an antifreeze system that does not have this problem. Suggestions please Art Tiroly ATCO Fire Protection/Tiroly 24400 Highland Rd CLE 44143 216-621-8899 216-570-7030 cell [https://ipmcdn.avast.com/images/icons/icon-envelope-tick-round-orange-animated-tick-v1.gif]<https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=emailclient&utm_term=oa-2368-c> Virus-free. www.avast.com<https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=emailclient&utm_term=oa-2368-c>
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