What is 'pressure balancing' between spaces in 62.1?

• A. Pressure balancing is not required in 62.1.
• B. It ensures equal room pressurization across all zones at all times regardless of leakage.
• C. It is used to maintain the same temperature in all spaces.
• D. It ensures supply and exhaust air balance so that unwanted air movement does not spread contaminants.

Answer: (D)

Pressure balancing between spaces is about controlling the pressure relationship between rooms so air flows are directed in a way that prevents contaminants from spreading. By balancing supply and exhaust air, the system maintains the intended pressure differences, which keeps cleaner spaces protected from leakage of more contaminated ones.

This concept is not about making every space pressurized the same at all times, nor about equalizing temperature across spaces. Temperature control is a different function. The best description is that supply and exhaust balance to avoid unwanted interzonal air movement and contamination spread.