Up until now a method presented by MuscheIknautz has been used to predict the pressure gradient for pneumatic conveying in horizontal pipes. This method was developed from the basic approach of Earth and has been improved several times. Nevertheless, it has a considerable disadvantage in that detailed calculations are required. Wirth suggested a state diagram representing stable strand flow. However, all the non-dimensional groups in this state diagram contains parameters which have to be determined experimentally. The present work is concerned with a simple modification of Wirth’s diagram avoiding the disadvantages mentioned above. A comparison of measured results indicates the applicability of the new diagram even for flow regimes which exceeds strand flow type of conveyance.