Pump with suction and pressure control for dry particulate material

A method of pumping powder comprising:

• applying suction to a volume to draw material into the volume and applying positive pressure to push material out of the volume, opening an inlet flow path at time T3 and closing the inlet flow path at time T4, applying the positive pressure at time T5, time T5 being after the time T4 plus a delay for response time has elapsed to ensure the inlet flow path is fully closed before time T5 occurs.

A method of pumping powder, comprising:

• applying suction to a volume during a suction cycle to draw powder into the volume, applying positive pressure to the volume to push powder out of the volume during a delivery cycle, wherein within each suction cycle is a suction duration period during which suction force is applied to the volume, the suction duration period being shorter than the suction cycle and is approximately centered within the suction cycle.

A method of pumping powder, comprising:

• applying suction to a volume at time T2, opening an inlet flow path to the volume at time T3, the time T3 being after the time T2 plus a delay so that when the inlet flow path is opened an initial higher suction force spike is applied to draw powder into the volume.

A method of pumping powder, comprising:

• applying suction to a volume to draw powder into the volume, and controlling the flow rate of air from the volume during a suction time period.