What is the maximum opening for nozzles to prevent the pump from running dry?

The correct answer is based on the need to maintain pump operation without risking damage due to running dry. Allowing for a maximum opening of one third to one half of the nozzle ensures that there is enough water flow to keep the pump adequately supplied. This range allows for sufficient suction to maintain pump prime, while still accommodating variations in operation and usage demands.

If the nozzle were opened too far, such as more than half or fully, the risk increases for the pump to run dry, particularly under low supply conditions or unexpected fluctuations in water flow. Maintaining the nozzle opening within this specific range balances effective water delivery while protecting the pump from running without sufficient water, which could lead to overheating and damage.

Understanding this limit is crucial for fire rescue operations, as it helps ensure reliable pump performance and effective firefighting capabilities.