Positive Displacement Machines

Positive displacement liquid filler are designed to use either a piston or pump to displace the proper volume of product into a container or bottle. Positive displacement fillers can also be used to fill pastes, up to a certain viscosity, into a container.

Positive displacement fillers that use pumps rely on the known quantity of product displaced by one revolution (or fraction thereof) of the pump to dispense the proper amount of product into a container. To reach a certain fill volume, the pump is rotated the proper number of times to reach that volume.

Positive displacement fillers that use pistons to fill the proper volume of product into a container rely on knowing the volume of the piston. A piston filler is designed so that the piston draws back within the cylinder (increasing the volume of the cylinder); product is drawn into the cylinder to fill the empty space (volume). A rotary drum valve is then rotated to change the connection of the cylinder from the product tank to the fill nozzle. The piston is then pushed into the cylinder reducing the volume in the cylinder and pushing product out through the fill nozzle. The rotary drum valve then rotates again to connect the cylinder to the product tank preparing for the next fill. The volume of the fill can be adjusted by changing the amount of draw on the piston, which changes the amount of volume in the cylinder once the piston is drawn back.