While pump design is critical to ensure its cleanability, it means nothing without a properly designed clean-in-place (CIP) system.
There are many aspects to a proper CIP systems, but let's focus on those that affect cleaning inside the pump.
Please note, these are only guidelines; each situation has unique needs.
A circumferential piston pump has tight clearances between the rotors and the housing which attributes to its high efficiency. When you are running products or cleaning solutions with different temperatures, allow enough time for all of the wetted components inside the pump to reach a steady-state temperature before running the pump. If your process does not allow you to stop the pump during this transition, you should install rotors that provide larger clearances.
To ensure that you have the proper flow rate (often 5m/s) to clean the entire circuit and adequate turbulence inside the pump, use a separate CIP supply pump and a bypass loop around the pump (see illustration).
During CIP, the pump should operate slowly (10-100 RPM). A slower rotation promotes turbulence and cleaning.
For less viscous products, differential pressure within the pump (inlet to outlet) should be at least 10 PSI to promote the resonance time of CIP solution in the pump. For higher product viscosity, the required differential pressure may need to be increased to 30-50 PSI. The means of applying back pressure is often a valve after the pump.