Steel pipes corrode quickly in dry sprinkler systems. The concepts behind corrosion and MIC are explained in this blog:Understanding Corrosion and Microbiologically Induced Corrosion (MIC). Both wet and dry (pre-action) sprinkler systems have corrosion issues, but they are dramatically worse in dry systems.
Corrosion exists in almost every fire sprinkler system installed. Some systems are always filled with water – wet pipe systems. Some systems have air in the pipes until the system is called to fill with water – dry pipe and pre-action systems. Both wet and dry systems have corrosion issues, but they are dramatically worse in dry systems.
If you think it might be handy to have a quick reference guide to the NFPA, Fire Protection Systems: Inspection, Test & Maintenance Manual, you are not alone. ORR Protection Systems has put together an easy to reference, quick guide to give a clear timeline (e.g. weekly, monthly, quarterly, annually) of requirements for functional testing and visual inspection.
The ability for the gaseous agent to be retained in the protected room for an extended period of time is critical to the performance of any total flooding clean agent fire extinguishing system. NFPA 2001, Standard on Clean Agent Fire Extinguishing Systems, requires that a minimum concentration of 85% of the adjusted minimum design concentration be held at the highest level of combustibles for a minimum period of 10 minutes. Those installing these systems are required to perform a Room Integrity Fan Test to assure the protected room will hold the agent for the required period of time.