How many inches of mercury should the priming device and pump achieve?

The correct answer indicates that the priming device and pump should achieve 22 inches of mercury. This measurement is significant because it reflects the vacuum pressure necessary for effective priming in a mobile water supply system.

A pressure of 22 inches of mercury ensures that the pump can adequately lift water from a source, overcoming the gravitational force and any friction losses within the system. Achieving this level of vacuum is crucial for maintaining the efficiency and operational capability of the pump. If the priming device does not reach this level, it may fail to create sufficient suction, possibly leading to air pockets or cavitation, which can damage the pump and inhibit water flow.

Understanding the importance of this specific measurement helps to ensure the proper functioning of mobile water supply equipment in emergency situations, where reliable performance is critical. Hence, a priming device that achieves 22 inches of mercury reflects optimal operational standards necessary for mobile water supply systems.