Massachusetts 2nd Class Fireman Practice Exam 2025 – Complete Prep Guide

To determine the absolute pressure from a gauge reading, one must understand the relationship between gauge pressure and absolute pressure. Gauge pressure only accounts for the pressure above atmospheric pressure, while absolute pressure includes both the gauge pressure and atmospheric pressure.

In this case, the pressure gauge reads 77.3 PSI. Standard atmospheric pressure at sea level is approximately 14.7 PSI. To find the absolute pressure, you simply add this atmospheric pressure to the gauge reading.

Calculating it yields:

77.3 PSI (gauge) + 14.7 PSI (atmospheric) = 92.0 PSI absolute.

The closest choice to this value is 90.3 psia when approximating, suggesting a slight difference due to possible rounding in the choices provided. This makes the first choice the most reasonable answer considering typical conditions and the close estimation to standard values.

This method serves as a foundational principle in pressure measurement, ensuring that you can accurately assess the total pressure experienced in a system, which is crucial for safety and operational practices in firefighting and engineering applications.