Which type of pump is known to be self-priming?

A flexible impeller pump is known to be self-priming due to its design and operation principles. This type of pump features a rotatable flexible impeller that allows for the movement of liquids even in the presence of air. The flexible vanes of the impeller can bend and uncouple from the pump body, creating a vacuum that effectively draws in fluid from the source, which means it does not require a separate priming mechanism to start the liquid flow.

This is particularly advantageous in applications where the liquid level may vary, or when the pump must start from a dry state. In contrast, centrifugal pumps generally rely on having liquid in the pump chamber for proper operation and usually require manual priming before they can function effectively. Variable volume gear pumps, while efficient for certain fluid handling, are also not self-priming and often require the system to be filled beforehand. The unique characteristics of the flexible impeller make it suitable for challenges involving air and liquid mixtures, affirming its self-priming capability.