Troubleshooting Liquid Fillers - Inconsistent Fills

One of the biggest advantages of a liquid filling machine is the addition of consistency to the filling process.  So of course when a cycle results in inconsistently filled bottles, this is a source of frustration for the packager.  While there can be many reasons for the inconsistency, the good news is that in most cases, the fix is quick and easy.  Below we take a look at some of the most common solutions for inconsistent fills.

 

 

Given the filling principle of filling to a level, visually inconsistent fills are the most worrisome for those using an overflow filler.  However, many times the differing levels are the result of a simple mistake during set up.  Overflow fillers can require the removal or addition of spacers on each nozzle when changing over from one bottle to the next.  The spacers should always be the first item checked when experiencing inconsistent levels.  If each individual nozzle does not hold the same spacers, make the necessary corrections.  Packagers using an overflow filler should also check the bottle seals for wear and tear, as a bad seal can also lead to inconsistent product levels.  Finally, all air lines and the product pathway should be checked as well.  Low air pressure, or pressure anywhere along the product pathway can cause inconsistency.  Check all hose barbs, locking collars or other components that may have become loose or could otherwise allow air into the pathway.

 

As to fills that are inconsistent on a volumetric level, this is not always an issue for overflow fillers.  As noted above, overflow machines fill to a level, regardless of the interior volume of the bottles.  In most cases, similar bottles will have a narrow range of interior volumes.  If volumes are way off, a packager's most likely solution is to talk to their bottle supplier about inconsistencies in the manufacture of the bottle, or change bottle suppliers. 

 

 

Gravity fillers, pump fillers and piston filling machines do not fill to a level, but rather to an accurate volume.  Visual inconsistencies in fill levels with these machines can once again mean a discussion with, or a change of, bottle suppliers.  If the bottles are not the issue, visually changes in fill levels might mean a change in product viscosity.  Some products will flow more freely or become more viscous with temperature changes.  The solution in this situation may be an attempt to control the temperature of the product during the storage and fill process, or as otherwise necessary to keep fills consistent.  Where this simply is not possible, a change in fill times, described below, may also provide a solution.

 

Fills that are inconsistent in volume are a bigger concern to most packagers using a non-overflow filling principle.  There are a number of reasons that volume can change on gravity, pump or piston fillers.  One of the most common again stems from set up or changeover of bottles on the filling machine.  Automatic machines will use a touch screen interface to enter a number of delay and duration times, including fill times.  These times may need to be adjusted for different bottles or even different fill heads when completing a volumetric fill.  As noted above, a change in product viscosity may also require a change to fill times.

 

For machines using a supply tank, a change in the head pressure can also cause inconsistent fills.  Again, on the operator interface, packagers should check the set up screen to ensure that the fill hold and supply hold are both on.  These two items will, in general terms, help to stabilize the head pressure during fill cycles by pausing the fill or the resupply when necessary.  Finally, air can once again be the culprit behind inconsistent fill levels.  Just like with the overflow filler, packagers using a volumetric filling principle should check their air lines and product pathways to ensure that no air is entering the pathway during the cycle.  

 

Of course, the above is not an exhaustive list of possible causes or solutions for inconsistent fills, but they do represent the most common issues.  If these simple fixes do not lead to consistent and reliable performance, it is probably time to call a Packaging Specialist and troubleshoot in more detail.