Why Moisture Control Matters in Dry-Pipe Sprinkler Systems
Many construction teams treat nitrogen generators as the default fix for dry-pipe sprinkler corrosion, assuming oxygen removal solves the problem. However, moisture, not oxygen alone, can quietly drive pipe failure long after installation. Understanding why moisture control matters in dry-pipe sprinkler systems tells a simpler story.
Recognizing the primacy of moisture control, some manufacturers have shifted their focus from oxygen displacement alone to directly managing moisture itself. General Air Products‘ Dry Air Pac systems exemplify this approach. The system is built specifically for dry-pipe and preaction sprinkler systems with moisture control as the core mission.
How Moisture Fuels Corrosion in Dry-Pipe Systems
Dry-pipe sprinkler systems rely on steel piping, and steel corrodes when metal, oxygen and water combine. Atmospheric oxygen fills the empty pipe between activations, supplying that second ingredient automatically. Water is the one variable teams can control, which makes it the thing most deserving of attention.
Two routine procedures introduce unexpected water. Hydrostatic testing fills the entire pipe network before installation, and trip tests release stored air to confirm the system functions properly. Both leave residual water behind even after the system drains, which settles in spots that are difficult to catch during a routine inspection.
Low points in piping compound the problem. Gravity pulls residual water toward sags, elbows and low-lying runs, where it collects into standing pools that keep feeding corrosion long after the visible pipe looks dry. These pockets sit in the exact locations teams are least likely to check during a walk-through.
This pattern is not just an industry assumption. NFPA’s 2024 coverage of new vacuum, or negative-pressure, dry-pipe technology confirms that the vacuum pump removes residual moisture to inhibit corrosion, independent of oxygen displacement alone. That reinforces moisture control as a recognized corrosion-fighting mechanism in its own right, not simply a by-product of removing oxygen, and it’s the same principle behind General Air Products’ dry-air systems.
Why Nitrogen Isn’t the Only Fire Sprinkler Corrosion Prevention Equipment Option
Nitrogen generators have been the default choice for many contractors. They are genuinely effective at displacing oxygen, flooding the pipe network with an inert gas and cutting off one leg of the corrosion triangle. However, this still leaves open the separate question of whether residual moisture, the piece that settles into low points and resists inspection, is being addressed at all.
Since moisture is the central issue, any method that removes or prevents moisture buildup deserves equal consideration alongside oxygen-focused solutions. The real question for each project is whether nitrogen alone covers everything a dry-pipe system actually needs.
Exploring Nitrogen Generator Alternatives for Dry-Pipe Systems
Other corrosion-control approaches address the same problem from different angles. Desiccant-based drying systems remove moisture mechanically, pulling it from the air supply before it ever reaches the pipe. Vapor corrosion inhibitors take a different approach entirely, forming a protective layer on metal surfaces rather than directly removing water or oxygen.
Dry air operates on a simpler mechanical principle than nitrogen generation, stripping moisture from compressed air before it enters the piping network and directly addressing the corrosion trigger. That principle is the foundation of General Air Products’ dry-air systems, which deliver dried air directly into dry and preaction sprinkler piping. This FM-approved twin-tower regenerative compressor and dryer package maintains a -40° Fahrenheit dew point, directly targeting the moisture that drives corrosion.
The field-tested track record of General Air Products’ Dry Air Pac makes the case in plain terms. Pipe samples ranging from three to 13 years old, pulled from active jobsites running the system, went to a third-party metallurgical lab for evaluation. Three of the four samples came back showing no corrosion at all.
Code bodies are taking note as well. NFSA’s coverage of the 2025 edition of NFPA 13 confirms the standard now formally recognizes additional corrosion-fighting technology, expanding beyond nitrogen-only solutions and giving fire protection teams more latitude to choose the method that fits their project.
Frequently Asked Questions
Construction teams weighing a switch to dry air often ask the following two questions.
Is dry air a good alternative to nitrogen in dry pipe sprinkler systems?
Dry air is gaining traction as an alternative for nitrogen generation because it targets moisture directly rather than just displacing oxygen. Lab testing of pipe samples pulled from active jobsites running General Air Products’ Dry Air Pac systems, ranging from three to 13 years old, found no corrosion in three of four samples. That track record makes dry air worth evaluating for many dry-pipe and preaction systems, particularly on projects where moisture control is the main concern.
What causes corrosion in dry-pipe sprinkler systems?
Corrosion happens when metal, oxygen and water combine inside the piping. Oxygen fills the pipe naturally between activations, but water is a controllable variable. It often lingers after hydrostatic testing or trip tests, settling into low points where it keeps feeding corrosion out of sight. The compressed air feeding the system can carry moisture in as well, which is why General Air Products’ Dry Air Pac dries that air to a -40° Fahrenheit dew point before it ever enters the pipe.
Keeping Dry-Pipe Systems Better Protected for the Long Haul
Moisture control, not just oxygen removal, sits at the center of long-term corrosion prevention for dry-pipe systems. As code bodies and contractors alike recognize how much residual water matters, the question is no longer which single method to default to.
The combination of equipment should fit the project’s age, layout and maintenance plan. Evaluating options with that full picture in mind can support a longer, more reliable sprinkler system service life. Contractors ready to make moisture control part of that plan can explore General Air Products’ Dry Air Pac systems to find the right fit for each project.
*Please note that this list includes sponsored content. Some of the companies, products, or services featured have entered into commercial agreements for placement. Sponsored placements do not necessarily reflect an endorsement and should be considered alongside other options in the marketplace.