Over the past year, Viking has conducted extensive testing of FM Approved and UL Listed Oxeo inert gas fire extinguishing systems to push industry understanding of clean-agent performance in challenging real-world scenarios. We’re excited to share results that open new doors for designers and engineers approaching Class B fuel hazards and rooms with unclosable openings when using nitrogen.
Clean agent fire suppression systems are widely specified for Class B hazards (flammable liquids, fuels, etc.) because they protect both people and sensitive equipment without leaving residue. However, real facilities often have conditions that fall outside traditional design assumptions, like unclosable openings such as voids, vents, corridors, or permanent penetrations that cannot be sealed. Historically, these openings have required additional agents to ensure the system can achieve and hold design concentration long enough to extinguish a fire.
The goal of our testing was to determine if additional nitrogen was required to maintain 85% of the design concentration for the required 10-minute hold time.
To evaluate whether nitrogen-based Oxeo systems can maintain their target design concentrations in rooms with unclosable openings, Viking conducted a series of controlled tests with multiple variables.
Elevation
The first round of testing took place in Caledonia, Michigan (approximately 810 ft. [247 m] above sea level), followed by a second round in Aurora, Colorado (approximately 6,229 ft. [1,899 m] above sea level). Testing at these locations allowed us to assess system performance across a broad range of geographic conditions and elevations.
Unclosable Opening Location
Multiple test configurations were evaluated at each location. While the room dimensions remained consistent throughout the testing, the location of the unclosable opening varied between setups. In Setup A, the lower vent was open, while in Setup B, the upper vent was open. The vents were approximately 5 sq. ft. in area.
Concentration Target
For each elevation and setup location, there were also 30% and 50% concentration targets being tested.
The testing found that regardless of the Oxeo system’s geographic location, no additional nitrogen was needed for design concentrations up to 50% in a room with 0.5% openings of total enclosed boundaries (including walls and floors).
Thanks to these validated findings:
The 2025 Oxeo testing effort represents a major step forward in understanding how inert gas systems perform in real world, imperfect enclosure conditions. With proven nitrogen performance up to 0.5% in areas with unclosable openings, designers and engineers can specify Oxeo systems with more confidence and greater flexibility. That’s why robust fire protection solutions from Viking are trusted above all.
If you’d like more details on Oxeo and its testing, please see the resources below.