The effects of clogging in pumps are manifold and change over time. This is demonstrated with time-resolved observations of the operating data on a test rig at the chair of fluid system dynamics of the Technische Universität Berlin. On the test rig, the head, flow, power consumption and efficiency of different pumps operating with artificial wastewater are recorded.
In the data, different clogging behavior reflect in the operating parameters. There are three major clogging-induced characteristics to be differentiated in the time-resolved measurements. For some aggregates there is a rapid drop in the hydraulic parameters right from the start due to initial clogging, with following stagnating performance. This is showcased on a semi-open two-channel impeller, where efficiency drops by 40 % at the very beginning of the measurement and subsequently stagnates. In other cases, like demonstrated here on a closed two-channel impeller, the operating parameters decline continuously over the entire measurement period due to increasing clogging. In the showcased example, the efficiency drops by over 40% in the first six minutes of the measurement due to initial clogging and keeps declining till the end for another 6%. Lastly, there are cases where self-cleansing mechanisms are identified. It is further shown that this phenomenon also highly varies in its timing and hydraulic effects.
Finally, it is concluded that all operating parameters must be monitored to generate sufficient knowledge about the clogging behavior of a given aggregate. Additionally, longer observation times are necessary to sufficiently identify effects like the self-cleansing of an impeller.