An airlock installed for an underground mine entrance must be capable of withstanding a pressure pulse of what value while open?

• A. 10 kPa
• B. 70 kPa
• C. 5 kPa
• D. 150 kPa

Answer: (B)

An airlock at a mine entrance is designed to survive a sudden pressure surge that can occur when the doors are open, such as from a nearby blast or rapid changes in ventilation. The pulse creates a brief, high differential pressure across the portal, and the airlock must stay intact so people can pass safely and the structure won’t fail.

The value used in practice is around seventy kilopascals. This level reflects a significant yet achievable blast overpressure that the portal could experience, ensuring the airlock can withstand the surge without deformation or failure during opening. Lower figures wouldn’t provide adequate protection against blasts, while much higher figures would be unnecessarily costly and complex to achieve.

So, the typical design requirement is a pressure pulse capability of about seventy kilopascals when the airlock is open.