Piston Fillers for Accurate Volumetric Fill

Piston Fillers For Accurate Volumetric Fill

Piston filling machines can be manufactured as tabletop, semi-automatic or completely automatic equipment.  These machines, while ideal for thick, or viscous, products, are versatile enough to handle a wide range of products.  Below we take a closer look at exactly how the piston filling machine achieves its accurate fill.
In general, the piston filler uses a three way valve to move product from a bulk supply or a hopper into waiting containers.  As the piston draws back from its cylinder, product flows into the cylinder from the point of supply.  Once the piston reaches the desired retraction point, the three way valve will change position, cutting off the supply to the cylinder.  At the same time, the valve will now allow product to flow from the cylinder into the containers.  As the piston returns to the cylinder, the product is pushed out into the bottles or other containers.  Since the volume in the cylinder will not change from cycle to cycle (or stroke to stroke), the piston filler is able to provide an accurate, volumetric fill with each cycle.  
Of course, this does not mean only one volume can be achieved with any given piston filler.  The stroke of the piston can be changed by the operator of the machine.  Once the stroke is set, the machine will continue at that volume until altered by the operator.  This allows not only for the accurate fill, but for the machine to handle a range of container sizes.
Tabletop piston fillers are ideal for companies with smaller production demands.  These machines typically include a simple hand wheel to adjust the stroke of the piston (or the volume), and easy speed adjustment and foot pedal operation, meaning the operator simply steps on a foot pedal to begin each cycle.  Both semi-automatic and automatic piston fillers can be manufactured on a fully portable frame.  Semi-automatic machines will normally require operator interaction similar to the tabletop model, including placement of the bottles and activation of the fill cycle.  The automatic filler will use a power conveyor and an indexing system to move bottles or other containers in and out of the fill area, and will use a PLC with touchscreen operation to set up the parameters for each production run.  
Piston fillers are versatile not only because they can handle products both thick and thin, but also because they can be modified to work with other common filling concerns.  Different nozzles can be added to a piston filler to control foaming products, or nozzles may even dive into bottles to complete the fill.  The piston filler is also an ideal machine for jams and jellies with fruit, sauces with vegetable chunks and other products with particulates.  Of course, the three way valve and nozzles for products with particulates would have to be matched to the piston to allow particulates to move clearly through the entire product pathway.
For more information on these liquid fillers, jump to our piston filler page or contact a Packaging Specialist at LPS today.