Packaging Liquid Products With Particulates – Grit to Chunks
While a great majority of liquid products do not contain particulates, not all liquid products are 100% liquid. What? Well, items such as hand soap may contain grit to assist in the removal of dirt and grime. Jams and jellies may contain solid chunks of real fruit to boost flavor or even nutritional value. Salad dressings and food sauces may contain spices and seeds as well. So while these are still considered liquid products, they contain some solids. Each of these products must still be packaged for consumption, just like any other product, and products with particulates can require specific or even unique machinery on a packaging line. gouri
Of course, when dealing with a product, the packaging equipment that will be effected is the liquid filler. Capping machines, labeling machines and other equipment may work while the product is present, but the particulates themselves will normally not require modifications or additions to such equipment. The same is not true for the filling machinery that will have to handle the product to move it from the bulk tank into the waiting containers.
First and foremost, supply tanks on some filling machines may need to be modified to include some type of mixer. Many times particulates, especially heavier particulates like chunks of fruit, will settle to the bottom of the tank, resulting in a very inconsistent fill as far as the amount of particulate goes. The mixer, or agitator, keeps product and particulates moving before the journey to the bottle or other container begins, allowing the product and particulate to flow to each container. Once a packager ensures that the solids will not settle in the tank, there is still the task of moving both liquids and solids to the containers, which will entail the travel through pumps, plumbing, tubing, manifolds, fill heads and/or nozzles. The size and amount of the solids in the product will help determine which filling principle will be used to complete the process.
It may come as a surprise to some in the packaging industry that an overflow filling machine can be used for some free-flowing products with smaller particulates. Overflow fillers are known in the packaging industry for creating reliable, level fills on every bottle used regardless of small inconsistencies in the internal volume of the different bottles. This is an advantage for items such as salad dressings that are sometimes packaged in clear containers in that it level fills allow for aesthetic appeal when the product reaches the shelf, rather than inconsistently filled bottles of the same product sitting side by side while on display. Once product reaches a certain level in the bottle, the excess fluid “overflows” through a return port on the nozzle, allowing the consistent fill as well as the reuse of product, if feasible. For an overflow filler to be successful with these type of items, the particulates must be small enough to move through the nozzle without clogging either the fill port or the return port. Clogging either of these holes with built up solids will result in inconsistent fill levels and defeat the purpose of the machine. Along the same lines, the product itself must be fairly free-flowing, as a viscous or slow moving product can increase fill times, allow solids to accumulate or both.
For products with larger particulates, or for thick products such as jams and jellies that include solids, the overflow filler is more than likely not an option. Instead, a pump filling machine or a piston filler will be used to package the product. Pump filling machines will use a single pump for each individual fill head. These pumps may will often be gear or lobe type pumps, essentially trapping product and particulates in an empty space between the gears or the lobes, then transferring the two through the tubing to the waiting containers. Pump fillers work well with thicker products, but may reach a limit when the size of a solid in the product becomes too large.
Piston fillers use a cylinder and a three way valve to pull and push product into and out of the cylinder respectively. The pistons can vary in size, meaning that a large piston will allow a large cylinder to be filled with product. The piston filler solves the problem of large particulates such as fruit chunks in the jams and jellies. The large open space of the cylinder allows these larger solids to pass to the containers, realizing, of course, that the nozzles used to fill jars or other containers must also be able to accommodate these pieces. In other words, the entire product pathway, from the bulk tank to the containers, must allow the particulates to pass. The piston also allows thick products to be filled with a highly volumetric accuracy, as the volume of the cylinder will not change from cycle to cycle.
While there may be other solutions for unique packaging projects involving products with particulates, a majority of these projects will be solved by incorporating a mixer or agitator and using one of the above filling methods. As always, each project should be analyzed on a case-by-case basis to find the most efficient, cost-effective and reliable manner of packaging a product.