Which reciprocating pump type can safely run dry without damage?

The diaphragm pump is designed with a flexible diaphragm that separates the pump chamber from the hydraulic fluid. This design allows for safe operation in situations where the pump might run dry, as the diaphragm can absorb changes in pressure and does not require the fluid for lubrication or cooling. As a result, diaphragm pumps can handle varying flow rates and can operate without fluid without sustaining damage, making them ideal for applications where dry running may occur.

In contrast, the other types of pumps listed, such as plunger, single-acting piston, and double-acting piston pumps, rely on the presence of fluid for lubrication and cooling of their moving parts. Running these pumps dry can lead to excessive wear, overheating, and subsequent damage to internal components, which can result in costly repairs or replacements. Thus, the diaphragm pump stands out for its unique capability to operate dry without sustaining damage.