Ice Blocks in Dry and Preaction Sprinkler Systems
When fire sprinkler systems are required in freezers, dry and preaction sprinkler systems are used because system piping cannot be filled with water. Air compressors that provide supervisory air pressure in these sprinkler systems routinely introduce small amounts of condensate moisture into the air. If enough water accumulates and freezes the resulting “ice block” within the piping can compromise the function of the fire sprinkler systems or rupture the piping itself.
In order to prevent sprinkler system ice blocks from forming refrigerated and desiccant dryers are often employed to dry the air before it is introduced into the freezer. By reducing the dew point of the pressure maintenance air to less than -20°F ice blocks can be prevented.
Air dryers coupled to compressors have been used for many years to minimize ice blocks in freezer applications. However, there are several disadvantages:
- Significant upfront cost
- Require regular routine maintenance to keep the air dry
- Contribute to corrosion in the piping by adding oxygen
Dual Benefit of Nitrogen Generators for Freezer Applications
Nitrogen generators produce dry nitrogen gas at a dewpoint of -20°F to -40°F. When nitrogen is used as the supervisory gas in dry and preaction systems in freezers ice blocks cannot form. In addition, nitrogen generators do not introduce oxygen to the fire sprinkler piping which is the primary cause of corrosion in these systems. Sprinkler supply piping exposed to room temperature conditions and liquid water will no longer corrode without the presence of oxygen.
Nitrogen generators coupled to air compressors:
- Produce dry nitrogen gas that will not form ice blocks
- Produce oxygen free inerted atmosphere that stops corrosion
- Require less maintenance than dryers
- Available at comparable cost to dryers
- Offer excellent durability – long life membranes (20 years)