A two-stage fire pump can operate in series/pressure mode or what other mode?

In the context of fire pump operations, a two-stage fire pump can indeed operate in two primary configurations: series/pressure mode and parallel/volume mode. In series mode, the pump stages work together to increase the available pressure, which is essential for reaching higher elevations or delivering water to systems that require significant pressure.

When operating in parallel/volume mode, both stages of the pump work simultaneously to increase the volume of water being delivered, which can be advantageous when there is a need for a high flow rate rather than high pressure. This mode is particularly useful in scenarios where large volumes of water must be supplied, such as in firefighting efforts at large fires or when feeding multiple lines simultaneously.

This understanding of pump modes is vital in selecting the appropriate configuration depending on the firefighting scenario, as it directly impacts the pump's effectiveness in addressing the fire. The other options do not reflect recognized modes of operation for two-stage fire pumps, thus reinforcing the choice of parallel/volume mode as the correct answer.