The NIST 20 MW Calorimetry Measurement System for Large-Fire Research
Rodney A. Bryant, Matthew F. Bundy
The National Fire Research Laboratory is a unique large-fire research facility; able to characterize the response of full-scale building systems to realistic mechanical loading and fire. The facility maintains an infrastructure of measurements necessary for accurately characterizing the heat release rate of fires, a key parameter in predicting fire hazard. This measurement infrastructure includes four oxygen consumption calorimeters to measure the heat released during fire experiments, and a fuel consumption calorimetry system (natural gas burners and flow control) to generate precise amounts of heat release. Both systems have a heat release rate capacity of 20 MW, twice the capacity of the previous facility. A rigorous evaluation of the processes for the measurements by oxygen consumption calorimetry and fuel consumption calorimetry has resulted in significant improvements in measurement uncertainty when compared to previous versions of the facility. Measurement agreement between the two independent systems has been demonstrated and provides evidence that NFRLs system of heat release rate measurements for large-scale fire research are the most accurate and highly characterized of their kind. The methodology, hardware, and performance of the large-fire calorimeters and natural gas flow system are described here to provide technical guidance on achieving accurate heat release measurements to laboratories with the mission of accurate large-scale fire testing.