- The significance of the acceleration zone is expressed when designing a straight pipeline that follows either the feeding point or a bend in a pneumatic conveying system. It is an effective and reliable system that takes into account the acceleration zone in the design process. The current paper presents a thorough experimental investigation of particle velocity profile at the acceleration region obtained from 3-in, 2-in and 1-in horizontal dilute phase pneumatic conveying systems with various operating conditions and conveyed materials. The velocity was obtained by using a high speed camera combined with image processing. Investigation of the statistical velocity distribution resulted in a new correlation for the particle velocity profile throughout the acceleration zone and the acceleration length in the range of the tested operating conditions.