This paper presents a comparison between the results from a test program carried out to characterize the blast load environment within BakerRisk's Deflagration Load Generator (DLG) test rig, and predictions made using the FLACS computational fluid dynamics (CFD) code. The test data was also compared to internal peak pressure predictions made using the National Fire Protection Association's Standard on Explosion Protection by Deflagration Venting (NFPA 68) [1]. The purpose of these tests was to provide data for comparison with standard methods used to predict internal blast loads in a vented deflagration. The tests also provided a characterization of the internal DLG blast load environment for equipment qualification testing.The DLG test rig is 48 feet wide × 24 feet deep × 12 feet tall and is enclosed by three solid walls, a roof, and floor, with venting through one of the long walls (i.e., 48-foot by 12-foot). During testing, the venting face of the rig was sealed with a 6 mil (0.15 mm) thick plastic vapor barrier to allow for the formation of a near-stoichiometric propane-air mixture throughout the rig. The flammable gas cloud was ignited near the center of the rear wall. Congestion inside the rig was provided by a regular array of vertical cylinders (2-inch outer diameter) that occupied the rear half of the rig; the front half of the rig was uncongested (i.e., as would be the case for equipment qualification testing). Forty-three pressure transducers were deployed internal and external to the rig to measure blast pressure histories.Three series of tests were conducted with congestion levels varying from an area blockage ratio (ABR) of 11% in Test Series A to ABR values of 7.6% and 4.2%, respectively, in Test Series B and C. The obstacle-to-enclosure surface area ratio (Ar), a perameter used within the NFPA 68 correlations to quantify congestion, was equal to 0.45, 0.32, and 0.17 for test series A, B and C, respectively. The peak pressures and impulses for each test are provided, along with pressure histories internal and external to the rig for selected tests. Comparisons of the test data to predictions made using the FLACS CFD code and NFPA 68 venting correlations are also provided.

Hydrogen is a key energy carrier for modern society. The breaking of the hydrogen bonds within traditional hydrocarbon molecules has been the primary mode of energy utilization since the industrial revolution. An increased focus on "net-zero" greenhouse gas emissions, specifically carbon dioxide and methane, has resulted in a global push for lower carbon energy vectors, including pure hydrogen. Accurately modeling the dispersion, fire, and explosion hazards associated with new and existing hydrogen production, distribution and transportation networks, and consumption is a key component to the safe expansion of these networks. BakerRisk performed a series of very lean hydrogen-air vapor cloud explosion (VCE) tests as part of an internal research effort. The goal of these tests was to better understand the VCE hazards associated with very lean hydrogen-air mixtures (≤14% H 2 ). Flame speeds and blast loads were measured using high-speed video and an array of dynamic pressure transducers. This paper discusses the test setup and test results, including a comparison with data from prior tests. The measured flame speeds are compared to those predicted using computational fluid dynamics analysis and referenced to deflagrationto-detonation criteria. Discussion regarding the application of these test results to facility siting studies is also provided.

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