The Pac-Van BRM has been subjected to stronger live field blast loads than its competitors. It is common knowledge in the blast-resistant design community that it is at best very difficult and extremely expensive to attempt to reproduce a long-duration vapor cloud explosion (VCE) in a live field test. Given this reality, high explosive testing must be used alongside computational analysis to validate a BRM for vapor cloud explosions. Using advanced finite element analyses, our design team determined that a live field test utilizing 1,250 lbs of ANFO at a standoff distance of 90 ft would subject the BRM structural components and connections to forces and deflections which would match those from a VCE of 8 psi and 200 ms. More specifically, computational analysis results showed that the recorded wall deflections from the live test data were extremely close to those predicted by computational models of the same BRM for a VCE of 8 psi and 200 ms. Other BRM manufacturers openly share that they have tested their units using 1,250 lbs of ANFO at a standoff distance in the range of 100-110 ft. Had we tested our BRM using an increased distance in this same range, the unit would not have felt the intensity of an 8 psi and 200 ms VCE. Our test results and computational analysis provide us the confidence to claim that we have validated our BRMs for their intended use in environments characterized by long-duration blast loads. As you consider your options, we challenge you to explore the following:
- Has the BRM manufacturer conducted live field testing of their product through an independent 3rd party?
- What charge weight, explosive material, and standoff distance was used during live field testing?
- Can the BRM manufacturer verify that the testing was adequate to validate the unit for its intended use with long duration blast loads?
This image provides a comparison between predicted free-field blast loads for 1,250 lbs of ANFO at 90 ft and 110 ft:
The Pac-Van BRM offers a “dual wall” approach which provides a higher level of protection for internal occupants and equipment than other BRMs on the market. Many BRM manufacturers have interior wall panels which are directly connected to the exterior blast-resistant wall system. During a blast event, these interior wall panels can be subjected to accelerations on the order of 20,000 in/s2 – more than 50 times the acceleration of gravity. An occupant leaning against this wall during the blast could expect to incur severe bodily injury at best. To avoid this interior hazard, the Pac-Van BRM has a secondary interior shell which is structurally separated from the blast-resistant walls and roof. When the exterior wall deflects inwards during a blast, it will not make contact with the secondary wall. While this wall will certainly feel the “rattle” of the blast event as the entire building is set into motion, it will not experience the direct force of the blast or dangerous accelerations which are characteristic of the exterior wall. When searching for the right BRM, always ensure that the unit you are selecting provides not only a strong exterior shell, but also an interior environment which is safe for your team and critical equipment during a blast event.