OVERFLOW FILLERS A Frain Industries Packaging Equipment Whitepaper There are several dozen styles of liquid filler available from over 100 US manufacturers. All have advantages and disadvantages and the range of choice may be overwhelming to the buyer who wants to know what kind of filler is "best". This whitepaper will discuss the class of filler commonly called "overflow" fillers. Subsequent whitepapers will discuss other filling architectures. There are two broad classifications of internal volume can vary significantly liquid filler. Volumetric fillers measure especially for blown glass bottles. If and dispense an amount of liquid filled volumetrically, the level of product independent of the container size. will vary creating an appearance of over and under fill. This is especially true The second class, level fillers, rely on when products are displayed side by the internal volume of the container. side on the store shelf. Level fillers are Level fillers fill the product a certain sometimes called "cosmetic" fillers distance from the top of the neck. This because they give the cosmetic distance will remain constant regardless appearance of a constant fill volume. of the container's internal volume. This www.fraingroup.com l (630) 629-9900 2 Volumetrically identical fill volume Cosmetically similar fill volume Level fillers are available in inline or There are two main disadvantages to rotary configurations for fill volumes level filling. One is that the fill quantity is from an ounce or less to multiple gallons dependent upon the container volume. If and speeds from 5-10cpm (containers the container's internal volume varies, per minute) to 1,200ppm and more. as with glass bottles, the amount of They are available for still liquids, as product in the container will vary. If the will be discussed here. They are also container volume can be well controlled, available for carbonated beverages there will be little variation in actual fill such as soft drinks and beer. This volumes and product giveaway is requires specialized configuration minimized. beyond the scope of this paper. Level fillers are also not generally Level fillers are generally simpler than suitable for viscous, non-free-flowing volumetric fillers of similar capacities. products that will not settle quickly to a This simplicity makes them easier to level surface. Filling in a hot, run, clean, set up and maintain. nonviscous, state may allow a work- Simplicity also makes them less around with some products. expensive to buy and operate. www.fraingroup.com l (630) 629-9900 3 This paper will confine itself to overflow cascade fillers, do this by passing the style fillers as they are the most can under a continuous stream of common and versatile. As the name product, tilting the can to control implies, they fill the container until it overflow volume. Excess product runs overflows. Some can fillers, called into a trough below for recirculation. Cascade Filler From Packaging Machinery Handbook These work well and can run at very to a can of Vienna sausages. A high (2,000+cpm) speeds. One disadvantage is that the container must advantage is that they can be used to be washed after closing. top off containers, such as adding brine www.fraingroup.com l (630) 629-9900 4 Overflow Fillers A much more common application uses sufficient time for a complete fill has a controlled overflow and been allowed, the nozzle is withdrawn. recirculation. The basic principle of As it is withdrawn, the spring closes the operation is that a filling nozzle is nozzle stopping product flow. Foamy inserted into the container and makes a products may be a problem in other seal with the container neck. As the types of filler but not in these generally nozzle continues into the container as the foam is driven out the overflow neck, the nozzle tip is forced open and back to the recirculation tank. allowing product to flow into the container via one of two channels. Air is Fill level (and volume) is determined by vented through the other. Once the how far the nozzle is inserted into the product level reaches the vent, it container as the product level can rise escapes through the vent and is no higher than the overflow vent. captured in a tank for recirculation. After Spacers or washers added to the nozzle control the entry depth. www.fraingroup.com l (630) 629-9900 5 This picture shows the typical nozzle with inflow and vent: Nozzles are commonly fabricated from The "O" ring, which seals the nozzle stainless steel but may be made from when closed, and the neck seal must be plastic and other materials as needed. chosen for product compatibility. www.fraingroup.com l (630) 629-9900 6 Gravity Configuration Overflow fillers may be gravity, A gravity configuration is shown below: pressure or vacuum. This configuration uses a gravity tank pump maintains a constant level in the above the filling nozzles. As the nozzles gravity tank. A constant level is are forced into the bottles and opened, important as changes in the head product flows into the bottle by gravity. pressure can result in changes in fill The height of the product above the volume. This occurs because during bottle determines the pressure and flow filling some bottles, especially rate. Normally a bulk reservoir with lightweight non-round bottles can www.fraingroup.com l (630) 629-9900 7 expand slightly. When the nozzles are Gravity fillers are generally suitable only removed, the bottle relaxes and the fill for low viscosity, water-like, products. level increases, sometimes to the point Viscous, products, heavier than a light of overflowing the neck. oil, will not flow quickly enough by gravity. Pressure Format The pressure format replaces the excessive pressure. gravity tank with a pump. This is often a centrifugal, non-positive displacement If the product being filled is a pump. Diaphragm and other positive suspension, it may be desirable to keep displacement pumps can also be used. it moving at all times to prevent the Pumps should generally be started particles settling. This may be done by when the fill nozzle opens and stopped keeping the pump running at all times as it closes. This is especially important with a bypass allowing circulation if a positive displacement pump is used directly to the overflow tank when not to avoid damage to the system from actually filling. www.fraingroup.com l (630) 629-9900 8 Vacuum Format The third arrangement is for vacuum and bottle there will be leakage out in filling. This is similar to the gravity the gravity and pressure configuration. arrangement but the overflow catch tank In the vacuum configuration, a damaged is sealed and maintained under neck will allow air to leak in rather than vacuum. The vacuum in the overflow product leaking out. tank creates a vacuum in the container when the valve opens "pulling" the One drawback to the vacuum product into the container. This can be configuration is that the container must useful with messy or flammable be rigid. Glass is fine, a heavy plastic products such as nail polish. In the bottle may also work well. If a light event of a damaged neck or other defect weight, non-rigid, container is used, the preventing a good seal between nozzle vacuum will collapse the container and little or no filling will take place. www.fraingroup.com l (630) 629-9900 9 Gravity Configuration Variation A variation on the gravity configuration The nozzles are similar to the others in is continuous motion rotary that they allow product to enter on one machines commonly used for milk and side and air to escape on the other. water filling. The product reservoir is Instead of overflowing to a catch tank, mounted above and rotates with the the air escapes through a standpipe in main turret. The filler nozzles are the bowl above the product level. There permanently mounted to the reservoir. is no actual product overflow or recirculation. If the product is filled cold (<100 de- Overflow fillers use the bottle neck to grees F or so) rubber or silicone di- push them open either by lowering the aphragms may be used instead of nozzle into the bottle or pushing the bot- springs. Hot-filled products will require tle up to open the nozzle. Some bottles all metal construction with springs and may be too lightweight to resist this high temperature "O" rings. downforce and will collapse. www.fraingroup.com l (630) 629-9900 10 In these cases, it will be necessary to Inline fillers generally use a drip tray that use a neck support to prevent collapse. moves under the nozzles as they are For an inline filler, this may be a "V" withdrawn from the bottles. Rotary ma- block that moves in to capture and sup- chines usually use a semi-circular tray port the neck during filling. A rotary filler that extends about 45 degrees of the may use a starwheel to support the neck turret. This keeps the tray under the as the bottle rotates around on the tur- nozzles at all times that the nozzle is not ret. Not all bottles have suitable neck over the bottle. rings so these must be specified when required. Overflow fillers can be a good choice for filling flammable products. They are sim- Dripping is another issue that must be ple enough that they can be built with addressed. The nozzles themselves pneumatic controls and pumps. The ab- have a simple "O" ring seal and should sence of electricity makes them inher- not drip if the "O" ring is in good condi- ently safe. This eliminates the complex tion.