In order to save energy, a Reducing Pressure Drop Stick (Repds) was installed in a new hydrocyclone to reduce the pressure drop. The flow field was disturbed by the introduction of the Repds and the separation efficiency was also affected. Experimental results of this study show that the circumferential position of the Repds can be neglected in reducing the pressure drop of the hydrocyclone. The drag reduction of the Repds increases with the increase of radial position of the Repds. There is an optimum ratio of the d(Repds)/D which reduces the pressure drop the most. The reduction of separation efficiency can be ignored if the parameters co-operate well. (c) 2012 Elsevier B.V. All rights reserved.