NIST 3 Megawatt Quantitative Heat Release Rate Facility: Description and Procedures.
NIST 3 Megawatt Quantitative Heat Release Rate Facility:
Description and Procedures.
(3527 K)
Bryant, R. A.; Ohlemiller, T. J.; Johnsson, E. L.;
Hamins, A.; Grove, B. S.; Guthrie, W. F.; Maranghides,
A.; Mulholland, G. W.
NISTIR 7052; 130 p. September 2004.
Keywords:
heat release rate; calorimeters; uncertainty; quality
control; gas sampling; data analysis; education;
training; burners; natural gas; oxygen consumption;
response time
Abstract:
The 3 Megawatt Heat Release Rate Facility (3MWHRRF) was
developed at the National Institute of Standards and
Technology (NIST) as a first step toward having broad
capabilities for making quantitative large scale fire
measurements. Such capabilities will be used at NIST to
validate fire models and to develop sub-grid models. It
will also serve to provide a data base for studying a
broader range of fire phenomena, and to address issues
related to material acceptance and fire codes. An
equally important objective is to provide templates for
use by other laboratories including commercial testing
facilities to improve the quality of their data. Heat
release is the result of the combustion of a fuel with
the oxygen in air. The fuels of primary interest are
those found in constructed facilities and include wood,
plastics, foam materials used in furnishings (such as
polyurethane), wire insulation (such as polyvinyl
chloride), and carpet materials (such as nylon). The
rate at which heat is released is the single most
important quantity in terms of fire safety. Thus it is
important that this measurement be made in a
quantitative manner. It is a key predictor of the hazard
of a fire, directly related to the rate at which heat
and toxic gases build up in a compartment or the rate at
which they are driven into more remote spaces. Heat
release rates on the order of 1 MW to 3 MW are typical
in a room that is flashed over or from a single large
object such as a bed or sofa. It is important that heat
release rate measurements be made accurately because
fire regulations are frequently based on peak rates of
heat release. Testing laboratories must be confident
that the objects tested pass the required regulation and
manufacturers need accurate information in defining the
fire safety characteristics of their products. A second
need for accurate heat release rate data is for the
development of quantitative models for predicting heat
release rate. In comparing a fire experiment and a model
prediction, it is essential that the heat release rate
measurement have an estimated uncertainty. The 3MWHRRF
developed at NIST meets the needs described above for
objects that can be placed under the 6 m OE 6 m hood,
which is approximately 4 m above the floor, or for
enclosures whose effluent can all be directed into the
hood. It is capable of measuring heat release rates in
the range of 0.10 MW to 3.0 MW including brief peaks as
high as 5 MW. As documented in this publication, the
expanded uncertainty (95% confidence interval) is 11% of
the heat release rates in the range of 0.10 MW to 3.0 MW
including brief peaks as high as 5 MW. As documented in
this publication, the expanded uncertainty (95%
confidence interval) is 11% of the heat release rate for
fire sizes larger than 400 kW. The response time of the
system is such that it can accurately resolve dynamic
heat release rate events of 15 seconds or more.
Building and Fire Research Laboratory
National Institute of Standards and Technology
Gaithersburg, MD 20899