Abstract: A fluid pumping assembly for pumping particulate material includes a pump housing defining a pump cavity including a pumping chamber for handling particulate material, a motive fluid chamber, and a moveable diaphragm. The fluid pumping assembly also includes devices for loading particulate material into the pumping chamber, and for injecting a high pressure, high volume purging fluid into the pumping chamber. Further, the fluid pumping assembly includes a control system having a control valve for shutting off flow of high pressure, high volume purging fluid into the pumping chamber when particulate material is being loaded into the pumping chamber, thus enabling dense phase loading of particulate material, and thereby optimizing a particulate material pumping capacity of the fluid pumping assembly.