Flexible Impeller Pumps

Flexible impeller pumps are part of the positive displacement pump family. They consist of a rotating rubber impeller with supple vanes attached. As the casing is smaller than the vanes, they must bend and then straighten as the impeller turns to conform to shape of the pump internal walls. The vacuum created push the fluid round from the inlet to the outlet.

Ensuring compatibility with the fluid being pumped is a vital part of flexible impeller pump specification to avoid swelling, erosion and even melting of the impellers. Our Liverani impellers are available in Natural Rubber, Neoprene, NBR, EPDM and Silicon. Upon disclosure of the fluid you are handling we will establish the best solution. Or view our chemical compatibility table here.

Unfortunately not! The fluid acts as a lubricant and coolant as the pump runs, so as well as risking the impeller melting, the mechanical seal could crack and result in leaking if it overheats. Consider a dry run protection device or float switch if there is risk of this happening.

Flexible impeller pumps are a relatively low cost solution compared to other pumps able to handle aggressive fluids, solids and viscous liquids. They are however limited in their pressure capabilities, so are usually reserved for more steady duty requirements.

Yes. Being able to operate in both directions makes flexible impeller pumps ideal for tank to tank transfer as well as returning excess liquid out of the pipework when transfer is complete.

Yes. The impellers are made of a supple rubber type material able to bend around soft solids without damage or jamming.

Yes! Thanks to the nature of the flexible vanes meaning that they maintain a tight seal with the internal pump walls they are ideal for where suction lift is required.