Which of the following is NOT a type of pump typically used in marine sanitation systems?

In marine sanitation systems, the type of pump used plays a crucial role in the effective movement of waste fluids. The correct answer identifies a type of pump that is generally not employed in these systems, which is the gear pump.

Gear pumps operate by the meshing of gears to pump fluid, generally used for applications involving fairly low viscosity fluids and are known for creating high pressures. However, in marine sanitation systems, the typical applications involve handling waste products that may contain solid materials, making the design and operational characteristics of gear pumps ill-suited for this purpose.

Other options commonly utilized in marine sanitation include flexible impeller pumps, which are well-regarded for their ability to handle varying viscosities and solids without clogging, diaphragm pumps, known for their reliability and capability to create a seal that prevents leakage of fluids, and simple piston pumps, which provide efficient transfer of fluids while also allowing for handling solids. Each of these types is better suited for the unique challenges presented by marine waste systems than a gear pump would be.