When Is An Antifreeze Sprinkler System Better Than A Dry System?
During the years when there were no listed antifreezes to protect fire sprinklers from freezing in severely cold weather, dry pipe systems were often chosen to fill the void after NPFA put into place new regulations requiring listed antifreezes for new systems. The most common applications affected by this included attics, unheated warehouses, commercial freezers, overhead canopies, loading docks and parking garages. Now that listed antifreezes are commercially available, however, it’s worth evaluating experiences from the field where dry system use increased in situations where it might not have been best suited. While these systems can be the right solution in some scenarios, they can have significant drawbacks in others.
In order for fire sprinkler systems to do their lifesaving work, they must be protected from damaging corrosion, which can flourish in both wet and dry sprinkler systems. While wet systems are permanently charged with static water that is released when the sprinkler activates, the term “dry” system is something of a misnomer, in the sense that this type of fire protection is subject to condensation from the compressed air equipment that charges the pipework in such systems. To address the issue, and because inert nitrogen acts as a drying agent, some facilities opt to replace the atmospheric air of the dry system with a costly nitrogen generator instead of a compressor.
To avoid corrosion in dry systems, the sprinkler system piping must be pitched to promote drainage of condensation at its lowest points. The arrangement requires piping to be pitched ½ inch per 10 feet (4 mm/m) for all branch lines, and ¼ inch per 10 feet (2 mm/m) for all other sprinkler piping. This adds to the installed costs of such a system, which also requires auxiliary drains for each pipe section to collect condensates from the pressurized air while minimizing loss of air pressure during maintenance. These systems are also often equipped with heat tracing to provide freeze protection, the cost of which ranges widely. Further, the need for pitched piping presents installation and inspection challenges in smaller facilities or those with complex roof systems.
Besides requiring dedicated staff time to inspect and drain, dry pipe sprinkler systems typically require ten additional system components, compared to just four for antifreeze systems. Additionally, maintaining dry systems can be three to four times higher than the initial installed cost, especially if a dry pipe valve has been persistently leaking or the compressor has needed excessive repair.
Shown is a comparison of a dry system's components against the simpler antifreeze system.
Overcoming Dry Sprinkler System Costs With freezemaster™ Antifreeze
A listed freeze protection product such as freezemaster™ antifreeze is formulated to meet NFPA requirements for all new fire sprinkler systems now and all existing systems by September 30, 2022. Building on more than 30 years in fire protection, Lubrizol formulated UL listed freezemaster™ antifreeze, a safe-to-use, factory premixed freeze protection technology with cold temperature protection down to -12ºF (-24ºC). freezemasterTM antifreeze stands out from the other listed alternative in that it:
- Provides the best protection against system failure and costly repairs
- Is dyed blue for easy identification of a fully flushed and filled system, saving installers from having to constantly test a clear fluid
- Is the only listed antifreeze approved for use with galvanized steel piping
- Offers breakthrough corrosion resistance that outperforms listed alternatives, effectively reducing pipe corrosion by up to 65 percent.
Once installed, the system need only be tested annually by a qualified inspector to ensure the freeze point is being maintained. Watch this video to learn more or download the Installation Guide for detailed instructions.