Glass Bottle Filling Machines: How to Compare Filling Principles

Compare filling machines by working out what the product, the bottle and the rest of the line require, and only then by how each filling principle behaves. A carbonated product, a viscous sauce with particulates and a still wine each call for a different filling method, and a machine rated for one may be unsuitable for another.

This guide is a selection aid, not a test report or a ranking. It covers five filling principles (gravity, vacuum or gravity-vacuum, counter-pressure, piston, and flowmeter or mass-meter), separates machines that fill to a level from those that fill by volume or mass, and ends with questions for suppliers. It names no best machine and gives no speeds or accuracies, because those depend on the product, container and configuration quoted.

What are you filling?

The product decides which principles are candidates. Write down the following before you contact a supplier:

• Still or carbonated. Carbonated products need the bottle held under pressure during filling so dissolved gas stays in solution. IC Filling Systems, an Italian filler maker, explains that any pressure variation in a carbonated product during filling expands the gas and creates foam, and that warmer product foams more.
• Viscosity and particulates. Several equipment makers’ guides treat viscosity as the main driver of filler choice. They describe gravity-type fillers as suited to free-flowing liquids and piston or pump fillers as better for thick products or those with particles, such as sauces and dressings.
• Foaming tendency. Protein content is one factor IC Filling Systems names for beer.
• Oxygen sensitivity. The Australian Wine Research Institute (AWRI) notes that headspace oxygen can be reduced through counter-pressure fillers, vacuum or inert gas application. Whether that matters depends on the product’s shelf-life requirements.
• Temperature. Hot filling, cold filling and ambient filling make different demands on valves, seals and the bottle.
• Volume claim. If the label declares an exact volume or weight, the filler’s measurement basis matters more.

Applications are covered in the guides to wine bottling equipment, beer bottling equipment and sauce and dressing bottling lines.

Which bottle and closure will you use?

The container is the other half of the specification. The filler has to seal against the bottle finish, center on it and, depending on the principle, fill to a point on the bottle or deliver a measured amount into it.

Collect the finish designation, the fill point or fill height, the brimful capacity and its tolerance, and the closure type, then compare them with what the filler supplier expects. Neck finishes and closure compatibility explains how to read finish designations. The glass bottle specifications checklist lists the dimensions worth putting on a drawing. The closure matters at this stage because it affects headspace. For wine, AWRI states that standard screw-cap finish bottles need more ullage (empty space) than cork-finish bottles, and that screw-cap headspace oxygen is generally higher because of this; the headspace and fill height you specify therefore depend on the closure you choose. The capping equipment guide covers the closure side.

How filling principles differ

Every filling principle either fills to level or fills by volume or mass. Filling to level stops the flow when the liquid reaches a set height in the bottle, so each bottle looks equally full. Filling by volume or mass stops the flow when a measured quantity has gone in, so each bottle gets the same amount. CFT, a food-machinery maker, notes that level filling compensates for small differences in container capacity but that the actual volume can then differ slightly between units, whereas a flowmeter delivers the exact volume regardless of container shape. Level filling is common for clear glass because the bottles look uniform.

The grouping in the diagram is a simplification. One maker, LPS, describes gravity fillers as dispensing by volume with a pre-set amount, while other sources describe gravity and counter-pressure glass-bottle fillers as stopping at a level. Ask each supplier which measurement basis its proposed machine uses.

Principle	How it fills	What stops the fill	Sources associate it with	Points to confirm
Gravity	Product flows from a raised tank into the bottle	Level or timed or set volume, depending on design	Free-flowing, still liquids	Foaming, oxygen exposure, measurement basis
Vacuum or gravity-vacuum	Vacuum in the bottle draws or assists product in	Level, set by the filling element	Still wines and similar products	Vacuum source, gas return, product carried back
Counter-pressure (isobaric)	Bottle is pressurized to match the tank, then fills	Level, as in a gravity filler	Carbonated products	Pre-evacuation, gas supply, snift, foam control
Piston	A cylinder draws in and pushes out a set volume	Piston stroke	Viscous products and those with particulates	Valve passage for particles, shear, cleaning
Flowmeter or mass meter	A meter measures what passes through the valve	Meter reading reaches target	Still and carbonated beverages, wide viscosity range	Product conductivity (for electromagnetic meters), calibration, cleaning

Gravity

Equipment guides describe a gravity filler as a tank above the fill heads that lets product flow into the container with no other force. Volumetric Technologies, a filler supplier, associates gravity fillers with low-viscosity, free-flowing products. A wine-production textbook lists gravity, counter-pressure, and vacuum with counter-pressure as the three classes used in wine bottling and calls gravity the simplest.

Vacuum and gravity-vacuum

Vacuum filling lowers the pressure in the bottle before or during the fill. In the usual description, which you should confirm with each supplier, the filling element’s return tube sets the level and any excess is drawn back. An Ohio State University extension paper says that vacuum before filling, with inert gas flushing, has been reported to lower oxygen absorption at bottling, and that a line with a vacuum filler can reduce headspace oxygen.

Counter-pressure (isobaric)

IC Filling Systems describes the cycle: the bottle is sealed by the filling valve, optionally evacuated of air (a step it says is a must for beer, cider and some delicate wines), pressurized with CO2 to the tank pressure, filled while gas escapes through a controlled vent, then depressurized and capped. Beer and some other products may be foamed slightly before capping to push air out of the neck. For specification, the gas supply, evacuation steps and foam control all depend on the product.

Piston

Piston fillers draw a fixed volume into a cylinder and push it out. CFT groups them under volumetric filling and describes a range from thin liquids to dense pastes or products with solid particles, used for sauces, jams and spreads. LPS says piston fillers may include heating for hot products and may fill thinner products when particulates are present, such as salad dressings or sauces. Ask about particle size limits and valve design.

Flowmeter and mass meter

CFT describes flowmeter filling as using electromagnetic or mass flow meters to measure the volume dispensed, suited to delivering an exact volume regardless of container shape or transparency. Electromagnetic meters need a conductive liquid; mass (Coriolis) meters measure mass directly. CFT also lists load-cell (net weight) filling as a separate technology that measures mass inside each container. Ask how the meter is calibrated.

What must match the rest of the line?

The filler is where bottle, closure and product meet, so most line interfaces touch it. The guide to planning a glass bottling line explains how to set speeds and buffers around the pacing machine; for the filler specifically, confirm these:

• Infeed and rinsing: the bottle must arrive in the orientation, spacing and condition the filler expects.
• Closing: the time between filling and capping, any foaming or purge step, and whether the filler and capper are synchronized. See capping equipment.
• Closure feed: closure type and size decide what the capper needs, so settle them before the filler order.
• Cleaning: product contact parts and cleaning method between products.
• Format changes: which valves, centering bells or starwheels change with a new bottle.
• Utilities and gases: CO2, nitrogen, compressed air, vacuum and water supplies and their quality.

Questions to send suppliers

1. Which filling principle do you propose for my product, and why does it suit the viscosity, particulates, carbonation and foaming I described?
2. Does the machine fill to level or by volume or mass, and what is the measurement basis for the fill I need to declare?
3. What bottle data do you need (finish, fill point, capacity tolerance, weight) and what tolerances do you assume?
4. What are the rated speed and the fill performance, and on what test product, bottle and conditions were they established?
5. What gases, vacuum, water and compressed air does the filler need, and at what quality?
6. How are product contact parts cleaned, and what is the cleaning cycle between products?
7. What change parts are needed for a new bottle, and what is documented for changeover?
8. How does the filler communicate with the capper, conveyors and inspection, and what happens to the line when the filler stops?
9. What is included in the quote: valves, tank, controls, guarding, spares, installation, acceptance testing?

Use the answers with the bottling equipment RFQ checklist so quotes can be compared on the same basis.

Evidence and limitations

Filling principles are described here in general terms from published explanations by equipment makers, an industry research institute and a university extension paper. Where a source describes a principle with a particular product (still wine, beer, sauce), that does not mean it applies to your product. Machine designs combine these principles in different ways, terminology varies between makers, and the same maker may place a technology in a different group than another. No source in this list gives a head-to-head comparison, so no principle is presented as better than another. Speeds and accuracies are omitted because they are configuration-specific and supplier-stated. SG Containers Review analyzes sources and does not test machines.

• Types of filling machines, CFT Food Machinery: flowmeter, level, weight and piston (volumetric) filling and what each measures.
• Counter Pressure (Isobaric) Filling, IC Filling Systems: the counter-pressure cycle, pre-evacuation and foaming behavior.
• The Most Commonly Manufactured Liquid Filling Machines, Liquid Packaging Solutions: gravity, overflow, piston and pump fillers and level versus volume filling.
• Understanding the Four Main Types of Liquid Filling Machines, Volumetric Technologies: product viscosity and filler type.
• Dissolved Oxygen During Bottling, Ohio State University (OARDC): vacuum before filling and vacuum fillers in relation to oxygen pickup.
• Oxygen pick-up during packaging: understanding total package oxygen, Australian Wine Research Institute: headspace oxygen, counter-pressure fillers and screw-cap ullage.
• Wine Bottling Operations, Apex Learning (Wine Production textbook site): gravity, counter-pressure and vacuum filling classes.