In many industrial processes where raw materials are required in bulk, pressure discharge trucks (usually referred to as PD trucks) are commonly used to transport them from the supplier's warehouse or mine to the processing plant or final client. By means of a pneumatic conveying system the content of the truck is unloaded and transported through a pipeline into a storage silo. This type of material handling system does not employ any bags and/or containers to transport the materials, it is enclosed and easy to operate, and hence, it is less expensive overall if large quantities of materials are to be transported on a regular basis.

In this article, attention is centered on the design and operation of PD trucks, from a pneumatic conveying viewpoint, including a description of several problems encountered in the field. Examples of different applications and bulk materials are also presented.