I have a project with a typical compressed air dry sprinkler system in an unconditioned attic space (site is at 44 deg latitude). The system is 22 years old.
Site maintenance person reports that they've had issues with this system for at least 15 years. Frequent and repeated leaks, predominately pin holes in the mains. They try to repair before the system gets wet, although not always in time. They recently replaced a 3 inch main and found that it was about 30% filled with sludge. Sludge was dark brown, almost clay like, sludge. Any thoughts on how such a large volume of sludge can accumulate in a dry system? Thanks in advance. Sent in anonymously for discussion. Discuss This | Submit Your Question | Subscribe
5 Comments
Dan Wilder
1/21/2021 09:21:08 am
This is gong down the road of corrosion and/or MIC.
Reply
Jesse
1/21/2021 09:30:32 am
Its probably all related.Typically, the overall cause is the combination of water, metal, and the oxygen in the air, The overall corrosion may be MIC, galvanic, or electrochemical.
Reply
Franck
1/21/2021 10:14:44 am
You can also provide auxiliary drains to try to remove as much as possible water accumulation in the piping (they normally accumulate at the lower parts).
Reply
Jim
1/21/2021 11:49:08 am
I am in agreeance with comments thus far. I've also run across a few instances where the installing contractor did not pitch/slope the pipe in accordance with NFPA 13 causing trapped water in many areas throughout the system. Overtime these typically will be the first areas to fail.
Reply
Phil W
2/4/2021 11:35:54 am
In the UK we are mandated to use hot dipped galvanised pipe (not sure of NFPA requirements) but not everybody is convinced of the absolute effectiveness of reducing pin holes in future; I'd say if is certainly better than an plain internal pipe finish. Not certain of how this might inhibit organic matter developing; N2 is not a normal method in the UK (nor mandated) and so we would always use a compressor with a good quality de-humidifier and be sure to blow out any residual water over a period of weeks (I think you will find this process is described in some of the DPV manufacturers literature. For best results I would say N2 and hot dipped galvanised pipe is about the best you can do, coupled with regular internal inspections at random locations and especially at terminal ranges,
Reply
Leave a Reply. |
Free SignupSubscribe and learn something new each day:
CommunityThank You to Our Top
January '21 Contributors!
Your PostThe ToolkitSprinkler Designer or Engineer?
Get all of our tools, including the Sprinkler Database, Friction Loss Calculator, Fire Pump Analyzer and more: Filters
All
Archives
February 2021
Daily
Daily discussions are open-ended fire protection, fire alarm, and life safety questions submitted anonymously for the benefit of sharing expertise and learning from other perspectives. Anyone can submit a question here:
Exam Prep2020 PE Prep Guide
(Available Now!) PE Prep Series
(Available Now!) 2020 PE Prep Series
Current Leaderboard (Click to enlarge) PE Problems
Visit July-October for daily Fire Protection PE Exam sample questions.
Solutions are posted the day after posting. Comment with your solutions, questions or clarifications. Please note that questions posted are unofficial and in accordance with NCEES rules are intended to be similar to actual exam questions, not actual exam questions themselves. |