MechChem Africa November-December 2023

Ruaan Venter, Business Development Manager at IPR, the distributor of Toyo heavy duty slurry pumps in southern Africa, sheds light on the functions and applications of cutter fans in pump systems. The role of cutter fans in pump agitation ⎪ Water, wastewater and pumping solutions ⎪

T he integration of innovative features during pump design has enhanced performance and efficiency, with sig nificant benefits for lowering total cost of ownership. One such component, the cutter fan, plays a crucial role in achieving effective agitation and solids handling. “The cutter fan, also known as an agitator, has revolutionised heavy-duty submersible dredge pumps. Toyo Pumps was the pioneer ing manufacturer to incorporate this type of agitation into its designs,” says Venter, adding that its patented curved three-blade stirring attachment, threaded onto the pump shaft just below the suction inlet, became a gamechanger in handling solids-laden slurries. The primary function of the cutter fan is to dislodge and re-suspend solids, creating a slurry. As fluid flows towards the pump suction, the cutter fan redirects a portion of the fluid away from the pump, generating a fanning effect. This redirection and cyclic process results in a concentrated ‘pocket’ of high solid-content slurry directly in front of the pump suction inlet. This maximises the pumping efficiency and ef fectiveness, making it an essential feature for dredge pumps. To protect the cutter fan, a stand is attached to the bottom of the pump. For larger pumps, an additional stub shaft is placed between the pump's main shaft and the cutter fan, providing extra protection and stability during operation. During pump installation, it is crucial to differentiate the cutter fan from other com ponents. Operating the pump with a reversed rotation can lead to unscrewing of components during operation, resulting in potential damages and costly repairs.

To identify a cutter fan correctly, it is advisable to consult the pump's rotational arrow. The cutter fan is easily visible and recognisable as it pushes fluid away from the pump for agitation purposes. Observing the marked arrow during pump wiring ensures the correct rotation and installation of the cutter fan. Cutter fans have contributed significantly to the efficiency and effectiveness of pump systems, particularly in managing solids and enhancing agitation. A deeper understanding of the roles played by the cutter fan’s ability to redirect fluid and maximise solids management exemplifies the advancements in pump technol ogy. By correctly identifying and using cutter fans, pump operators can ensure optimal per formance and avoid unnecessary operational issues,” Venter concludes. www.pumprental.co.za

The cutter fan, also known as an agitator, has revolutionised heavy-duty submersible dredge pumps.

Left: Toyo heavy duty slurry pump can be fitted with cutter fans to achieve effective agitation and solids handling in arduous pumping applications. Right: A view of a Toyo pump's cutter fan or agitator with a competitor's agitator (black component) showing the size comparison.

November-December 2023 • MechChem Africa ¦ 9