Three sets of experiments were conducted for each aerator, with incremental tests
of performance while increasing the speed of A/C power supply to the motor: 30;
35; 37; 40; 42; 45; 50 Hz (paddling near 62; 73; 76; 82; 87; 93; 103 rpm). We plotted
the increasing trend of each speed-control series, and report the mean and standard
error of the three samples of data at each speed. The mean oxygen transfer rating