This system uses a Coriolis flowmeter to accurately measure the mass of product exiting the filling nozzle. Measuring the mass, rather than the actual volume, allows high precision even when the product's viscosity or density changes or when the product contains entrained air. It can be used with a pump, a pressure vessel or a gravity tank, because its motive force makes it ideal for a wide range of products, especially those containing delicate solids. Piston fillers are the traditional volumetric workhorses. They are simple, rugged and reliable.
Volume is a function of the cylinder diameter and is controlled by adjusting the piston stroke.
Pistons may be driven by a motor with a single revolution clutch or pneumatically for flammable products. Continuous motion rotary machines use a cam track to move the piston up and down. It's tough to improve on a classic, but in recent years several companies have done just that. Many manufacturers of piston fillers now offer such features as programmable stepper motor drives, ceramic pistons, electronically adjustable stroke and touchscreen controls. Fillers based on electronically controlled rotary pumps are offered by several manufacturers.