Filling and Sealing Packaged Foods
Practical Action
Filling viscous liquids and liquids that contain particles
Because viscous liquids do not flow easily, a dispenser or piston filler is the preferred option.
Dispensers are similar in operation to the equipment described in Fig. 1, but have a moving
piston in the cylinder to pump viscous products into the container). This equipment is relatively
low-cost but has lower production rates than piston fillers. A small gear-pump filler (Fig. 3) can
be adjusted to dispense viscous liquids at volumes from 20 -999 ml and has a an anti-drip
outlet that prevents food contaminating the sealing area of the container.
Fig. 3. Dispensing filler for viscous liquids
Photo from Glenvale Packaging Ltd.
A semi-automatic piston filler can either have a row of filling heads (Fig. 4), or they can be arranged
in a circle as a ‘carousel’ filler. In operation, a piston draws product from a hopper into a cylinder
and a rotary valve then changes position so that when the piston returns, the product is filled into
containers. Piston fillers are relatively expensive to buy and are therefore suited to higher production
volumes. This type of filler is less suitable for low-viscosity products, which can leak between the
piston and cylinder.
Fig. 4. Piston filler
Photo from Inline Filling Systems Inc.
Both low- and high-viscosity liquids may contain particles of food (e.g. fruit pulps, sauces and
pickles) and these are more difficult to fill because simple liquid fillers described above may
become blocked by particles. For manual filling, a wide-mouthed stainless steel or plastic funnel
is more suitable, and products can be pushed through the funnel using a plastic plunger. Filling
machines for high-viscosity liquids and liquids that have particles use servo pumps. Each filling
nozzle has a dedicated servo-controlled positive displacement pump, but the capital cost of this
equipment is high compared to other types of filler.
3