Why Am I Getting Uneven Fills with My Overflow Filler?

Overflow filling machines are made to fill each bottle to a specific level. These bottle fillers use a special nozzle that includes a return port, so that once liquid reaches that pre-set level, it overflows through a return port. The level fill is ideal for those packaging products into clear glass or plastic containers, adding aesthetic value to those products when they are aligned on the shelf for consumers. For this reason, uneven or unlevel fills can be frustrating for packagers. There are several reasons why this may occur for the user of an overflow filler, and below we will go over the most common issues causing this problem.

Fill Nozzle Set Up

Overflow fill heads dive into each bottle to create a seal, which stops the overflow from spilling out of the bottle and allows for the level fill. Each time a new bottle is run on the liquid filler, the fill head dive must be adjusted (assuming the bottles are different heights). By raising the fill heads and placing bottles in position under the fill heads, the correct height can be achieved for the bottles in production. Using either the power height on automatic machines or the hand crank height on semi-automatic machines, the nozzles can then be lowered until the springs on the fill heads are compressed. Typically, the springs should compress rather tightly, until a fingernail can be inserted between the coils. If compression is not correct on the nozzles, return ports may not open correctly, causing fills to be inconsistent.

Mismatched Spacers

Overflow nozzles use spacers to allow the operator of the filling machine to set the fill level. The spacers are usually hard plastic pieces found just above the nozzle tip and seal. For each fill head on a multi-head machine to fill to the same level, the spacers on each nozzle must be identical. For example, one bottle may use a half-inch and quarter-inch spacer to achieve the desired fill level. Another bottle may use a half-inch and eighth-inch spacer. If the inconsistent fills started after a changeover, the packager should always check to ensure that the correct spacers are on each nozzle on the machine.

Worn Components

Like almost all packaging machines, the overflow filler uses several wear parts when running production and filling bottles. Wear parts are those components that come in contact with product, bottles or other components of the machine and, as the name suggests, will suffer from wear over time. On overflow bottle filling machines, the nozzles include O-rings and nozzle seals that will occasionally need to be replaced. Worn nozzle seals can allow air to seep into the bottle or liquid to leak out of the bottle, which can both lead to inconsistent fills. Similarly, a worn O-ring can allow product to leak from the nozzle itself, never reaching the bottle. Operators can usually eyeball the nozzle to look for wear on the seal or leaking around the nozzle tip or body. These items are simple to replace, and users of overflow fillers should always keep spare seals and rings in stock to allow for the quick fix.

Loose Hose Clamps and Product Pathways

Finally, air leaking into the product pathway at some point during the fill can also cause unlevel fill results. When this is the case, operators should check hose clamps or other connections to ensure that there is no leaking and that the connections are tight. While air can get in through a crack in tubing or at other locations, the most likely culprit in these situations is a loose connection. If a loose connection is found, simply tighten that connection and try running production again.

In a majority of cases, one of the four situations described above will be the cause of inconsistent fills on an overflow filler. However, in rare cases more investigation may be necessary. Packagers suffering from unlevel fills can always call Liquid Packaging Solutions for troubleshooting assistance to help identify the issue. Packaging Specialists are available Monday through Friday during normal business hours to assist, and can be reached Toll Free at 1-888-393-3693 or by using the quick connect box found on the LPS website.