During a blast pressure event, what follows the initial high-pressure phase?

During a blast pressure event, what follows the initial high-pressure phase?

• A. Positive Phase
• B. Negative Phase
• C. Neutral Phase
• D. Secondary Phase

Answer: (B)

After the rapid rise in pressure of the initial shock (the overpressure), the air expands and the pressure drops below ambient. This drop is the negative phase (underpressure) caused by the rarefaction wave following the blast front. It’s the immediate second phase in the blast sequence and can contribute to damage through suction effects. In some environments, reflections can create later oscillations, but the phase that follows the initial high-pressure spike is the negative phase.

After the rapid rise in pressure of the initial shock (the overpressure), the air expands and the pressure drops below ambient. This drop is the negative phase (underpressure) caused by the rarefaction wave following the blast front. It’s the immediate second phase in the blast sequence and can contribute to damage through suction effects. In some environments, reflections can create later oscillations, but the phase that follows the initial high-pressure spike is the negative phase.