What is the minimum pressure needed for the 10-20-30 rule calculation?

The correct answer is based on the fundamental understanding of the 10-20-30 rule, which is used in firefighting operations to estimate the required pressure needed for effective fire hose operations over a typical distance. This rule states that for every 100 feet of hose used, an increase in pressure is required to ensure adequate flow and reach.

In the context of the question, the minimum pressure of 55 PSI is essential because it serves as a baseline to ensure that firefighting systems function optimally. Operating below this pressure could result in insufficient water flow, ultimately affecting the effectiveness of firefighting efforts.

Specific values like 40 PSI, 50 PSI, and 60 PSI do not provide the necessary minimum for various scenarios where sufficient flow and reach are critical. Therefore, understanding the 10-20-30 rule and its requirements helps fire operators to make informed decisions about maintaining the appropriate pressure level for successful firefighting.