Once the engine is shut off, what is the maximum allowable drop in system vacuum within 5 minutes?

The maximum allowable drop in system vacuum within 5 minutes is a key parameter to monitor in mobile water supply systems. A drop of no more than 10 inches reflects an acceptable level of system integrity and performance. This limit is critical because it indicates that the system is still operational and capable of maintaining its suction capability, which ensures that water can be drawn effectively from the supply source.

A drop greater than this could signal potential issues such as leaks or compromised seals in the system, which could lead to inefficiencies or failures during firefighting operations. Maintaining the vacuum within this threshold helps to ensure that the supply system remains functional, maximizing the effectiveness and safety of operations during emergencies.