In testing a water-based fire protection system, which measurement is crucial to compare with prior test results?

The crucial measurement to compare with prior test results when testing a water-based fire protection system is the water supply flow rates. This measurement is vital because it directly affects the system's ability to deliver water at adequate pressure and volume during a fire event. Consistent water flow rates are essential for ensuring that sprinklers can perform effectively, providing the necessary coverage to control or extinguish a fire.

By analyzing changes in water supply flow rates over time, inspectors can identify potential issues such as blockages, leaks, or deficiencies in the water supply infrastructure. Significant deviations from previously recorded flow rates may indicate that the system's performance is compromised, warranting further investigation or remedial measures. This ongoing monitoring helps maintain system reliability and effectiveness, ultimately ensuring safety during emergencies.

While the other measurements—system integrity, fire department connection pressure, and temperature readings—are important in assessing the overall performance and reliability of the fire protection system, flow rates provide a direct indicator of how well the system will perform under actual fire conditions. These factors may inform maintenance decisions, but flow rates are the most effective metric for ongoing comparison against past performance data.