AbstractTime‐averaged power dissipation rates have been measured in water in a 19.4 cm diameter reciprocating plate column operating at frequencies 0.6 to 3 Hz and amplitudes 5 to 20 mm. Measurements were also taken in water in a 15 cm diameter column operated at 1 to 5.7 Hz with amplitudes 1 to 10 mm. Several different types of doughnut reciprocating plates, fitting close to the column wall, were investigated. Power consumption at high amplitudes agreed with the predicted values using the quasi‐steady flow model, while at low amplitudes the data were more in agreement with a recently proposed acoustic model. The measured power dissipations were slightly affected by the spacing between adjacent plates, and by the alignment of the holes in the case of plates with 3 holes. Flow patterns around the reciprocating plates were also observed with the aid of a thin beam of light reflecting from small particles suspended in the liquid. Well‐developed circulation patterns were observed, depending strongly on the axial spacing between the plates.