Close That Loop
Locations where predominantly closed loop recalculating systems are utilized generally consider themselves safe from corrosion, fouling and scaling because they are theoretically closed from fresh makeup, contact no air, and should be in a state of equilibrium. Unfortunately it is very rare for theory to become reality. More often than not, failure to attend to the needs of the waterside of such a system results in inconvenient - if not disastrous -results.
What To Do
There are a number of inexpensive steps that can be taken - beginning at startup - to prolong the life of a closed loop indefinitely. In addition to being certain that the systems design is indeed correct mechanically (usually the engineer is hired for this, but it should be reviewed by the mechanical contractor as well as the maintenance department for possible omissions - once it is in, who's fault a mistake is does not matter.)
The following items need to be included in the plans for startup and maintenance of the system
- Pre-startup Cleaning - not just a water flush, but a proper chemical cleaning overseen by someone who knows the proper steps to take.
- Post Cleaning Flush - a necessary final step in the above, this should include a final water analysis to be sure all the cleaning material has been removed along with the dirt.
- Initial Treatment Addition - a Re-calculated amount of treatment additive should be charged to the system to get the program off to a good start. Again supervision is an important feature.
- Subsequent Regular Checks - the system should be regularly checked by both program administrators (the Water Treatment Firm) and maintenance personnel.
Taking these steps can help your facility enjoy the benefits of a properly treated and operated closed loop, avoiding some of the nightmares we have seen in improperly treated systems.
We have seen many, including a school heating loop that was so dirty the water looked like India Ink. The reports sent in response to samples sent away always said "Add more chemicals". We were called in when the loop water began emitting a foul odor, manifest when a pipe leaked in a classroom. The loop had to be dumped, disinfected, flushed, cleaned, flushed and put back on line (all over a weekend). Since then proper procedures keep the loop operating as designed.
It turned out the loop had never been cleaned, and the dirt settled out of the samples in transit to the water treater, so he was unaware of the gravity of the problem.