Oxygen reduction (or hypoxic) systems are being used in warehouse facilities as an alternative to sprinkler protection. The basic principle of operation is to displace the ambient oxygen in an enclosed environment with one or more nitrogen generators. Two test methods that are available today to determine the reduced oxygen level needed for property fire protection purposes are described in the following documents: VdS 3527, Oxygen Reduction Systems Planning and Installation British Standards Institution PAS 95 (BSI PAS 95), Hypoxic Air Fire Prevention Systems
Concerns with these two methods have been expressed by Nilsson and van Hees1, which include:
- The point of igniter application is not defined (research indicates this affects test outcome)
- No sustained external heat flux is maintained once the initial igniter is removed, and under actual real-world conditions an ignition source may be sustained (such as an electrical ignition source or exposure to a fire)
- Behavior of composite materials is not addressed
- Behavior of a smoldering fire is not evaluated
- Generation of products of combustion is not evaluated
The conclusion is that the reduced oxygen levels established by these two tests are only valid for the tested conditions and may not represent real-world conditions. This conclusion is supported by Xin and Khan2, where laboratory scale testing suggested that lower oxygen concentrations than those found using the VdS 3527 or BSI PAS 95 methods are necessary for adequate fire protection.
Research goal: Conduct a literature review to clarify the current state of oxygen reduction system design and testing and perform a gap analysis by comparing current approaches to real-world applications.
Download the project summary. (PDF)
1 M. Nilsson and P. van Hees, “Advantages and challenges with using hypoxic air venting as fire protection,” Fire and Materials, 38, p. 559-575, 2014.
2 Y. Xin and M. Khan, “Flammability of combustible materials in reduced oxygen environment,” Fire Safety Journal, 42(8), p. 536-547, November 2007.