The following is paid content sponsored by BlackBox Biometrics Inc.
By Police1 BrandFocus Staff
Explosive breaching is a necessary, life-saving tool for SWAT teams and tactical operators, but the safety aspects of this practice have long been more of an art than a science. That’s beginning to change, thanks to a wearable, portable tool from BlackBox Biometrics. The Blast Gauge System, designed to monitor an individual operator’s exposure to blast shockwaves, can be used to measure the levels of pressure at various points and accurately pinpoint the minimum safe distance (MSD) for stacking up.
MSD calculation was established to ensure safe operation and avoid damage to unprotected eardrums or vital organs such as the lungs. While the MSD calculation may not prevent brain injury, it is the tool most often used by breachers to ensure that overpressure exposures remain below 4 psi. However, these calculations are often inaccurate.
Limits of the MSD equation
Variables in the standard MSD formula include the size of the charge and some basic information about the environment, but the formula doesn’t take into account every variable, such as the number of walls or obstacles in the breaching area. In a complex environment, this makes the calculation virtually meaningless.
Overpressure is both reflected and multiplied as it hits and bounces off any hard surface, competing with the original wave of overpressure. Within a confined space, officers are bombarded by all the colliding waves, with walls acting as a force multiplier. When stacked against a wall, officers are caught in a Mach stem, which is an area of increased pressure resulting from interaction of the original blast wave with the wall.
“The MSD calculation completely falls apart when you’re doing an interior, complex charge,” said Scott Featherman, a former Army breaching and explosives expert and business development manager for BlackBox Biometrics, which developed and manufactures the Blast Gauge. “In any sort of a complex environment, you can’t trust your MSD formula. The Blast Gauge can help you when it comes to all those details that no equation will ever take into account.”
Measuring overpressure with the Blast Gauge System
Using the Blast Gauge System takes the guesswork out of determining minimum safe distance and understanding the complex blast environment. The process is simple:
- Calculate MSD using the standard formula.
- Place blast gauges at the blast site, at the distance the MSD formula specifies, and at both half and twice that distance.
- Detonate the charge.
- Check the measurements as reported by the gauges.
In many cases, you’ll find that pressure is still well above 4 psi at the calculated site. The gauges provide concrete information that demonstrates what’s actually happening as opposed to what the math suggests. This information helps prevent avoidable blast injuries during training and enhances breachers’ understanding of blast pressure.
Avner Klein, an experienced SWAT officer and trainer who owns and operates Forced Entry Tactical Training, uses the Blast Gauge System to verify MSD and study the effects of blast pressure in his training operations. He says the Blast Gauge System makes it easy to demonstrate the limitations of the MSD formula and measure overpressure at various distances.
“We understood that the formula was not really accurate, but now you have a measuring device that is able to show you – hey, the math is the math, but this is reality,” said Klein. “You can now put sensors around the area where you’re going to detonate the device, and within a few seconds get the actual results. It’s a great tool, and it fills a wide gap that we’ve had for many years in explosive breaching.”
Shrapnel and burns are not the only hazards of explosive breaching. Blast overpressure, even at the widely accepted “safe” level of 4 psi, can cause traumatic brain injury and neurological deficits after multiple exposures. The Blast Gauge System is an objective tool that can improve officer safety by accurately measuring minimum safe distance in addition to monitoring individual officers’ exposure to overpressure.
For more information on blast sensors, contact BlackBox Biometrics Inc.