How to choose a liquid filling machine: a technical guide for industry

A filling line is an investment that stays with the company for decades: the mechanical life of a good filling machine comfortably outlasts the control systems that govern it. So the choice is not only about the purchase price, but about the total cost over time: how much product is wasted through inaccuracy, how much time is lost on each format changeover, how much it costs to clean between batches, and how easy it will be to get spare parts and service ten years later.

The most common mistake is to start from the machine catalogue instead of starting from the product itself. Two plants that both fill "one litre" may need completely different equipment if one fills water and the other a foaming adhesive. The right machine is the one that adapts to your product, your container and your rate, not the other way around.

This guide follows the same order we use when a customer contacts us: first the product, then the container, then the production, and only then the dosing technology and the type of machine. If you answer those questions in that order, the configuration almost defines itself.

The liquid you are going to fill is the variable that shapes the equipment the most. A fluid, stable product is not the same as one that foams, oxidises on contact with air, attacks materials or carries particles in suspension. Before thinking about machines, it helps to describe the product precisely.

The points that define the filling technology are viscosity, the tendency to foam, corrosiveness, flammability, the presence of solids and the working temperature range. A viscous product needs nozzles and valves designed so the jet does not draw in air; a foaming one, laminar-flow dosing; a corrosive one, special materials; a flammable one, an explosion-proof installation.

The second data point is the container: its size, material, shape and mouth type. BSC equipment covers a very wide range, from a 100 ml container to a 1000-litre IBC, and a single machine usually handles several formats with a quick recipe change. Defining the range of containers you will handle avoids buying a machine that is too small or oversized.

It also matters whether you will fill a single product or several, and whether you need a dual chamber (1+1) to fill two different products into the same container. The shape of the container (round, square, rectangular) and the cap type (threaded, press-on, valved, with dropper insert) shape the capping stage and the line integration.

As a rule of thumb: small and medium containers (100 ml to 20 litres) are handled by a linear filler or a monoblock; drums and IBCs (200 to 1000 litres) call for a dedicated drum filler; and flexible bladders, a bag-in-box filler.

The number of containers per hour you need determines the level of automation and the number of filling nozzles. It is best to think about the real production peak and the number of shifts, not just the average. A machine that runs with headroom lasts longer and fails less than one pushed to its limit.

For reference, a BSC linear filler produces around 2,000 to 4,000 bottles per hour in 1-litre containers depending on the number of nozzles, and up to 1,200 containers per hour in 20-litre jerrycans. A drum filler reaches between 5,000 and 6,000 litres per hour in 200-litre drums. These numbers are a guide; the exact configuration is defined with your product and container.

Here comes the most technical decision, and the one that most defines accuracy. Modern technology replaces the old level tank with electronic flowmeters: the product travels from a pump to the filling valve through closed piping, without oxidising and with no moving mechanical parts.

The electromagnetic flowmeter measures volume using the conductivity of the liquid (Faraday law). It is an excellent option for watery, conductive products, with very good accuracy and no maintenance. The mass flowmeter, based on the Coriolis effect, measures the mass flowing directly and does not depend on conductivity, which greatly widens the range of products that can be packaged, including non-conductive ones. For drums and IBCs, filling by weight with a scale is also used.

As a decision: if your product is watery and conductive, the electromagnetic option is usually enough and more economical; if it is non-conductive, highly varied or high value, the Coriolis mass option is the safest choice. The accuracy of BSC equipment ranges from plus/minus 0.2 % in small containers to plus/minus 0.03 % in 20-litre containers and drums.

With the product, container and production clear, the type of machine almost chooses itself. Each architecture solves a different scenario:

The linear filler is the most versatile for bottles, cans, pails and jerrycans up to 20 litres: a single machine fills several formats with quick changeovers. The monoblock combines filling and capping in a single compact machine, ideal when space is limited or to avoid moving uncapped containers between machines, and is common in chemical, pharmaceutical and veterinary work. The drum filler is designed for 200-litre drums and 1000-litre IBCs, with a bottom-up valve. The bag-in-box filler packages flexible bladders under ultra-clean conditions.

Filling is only one part. Most lines also need to cap, and often to label, case-pack and palletise. The automatic capping machine places and screws the cap container after container, with capping torque adjustable for each cap type, and can handle threaded, press-on and valved caps.

If your project covers more than filling, it is best to plan the full line from the start: the feeding table, transport between stations, capping, heat sealing, labelling, case packing and palletising. BSC integrates its fillers and cappers with equipment from partner manufacturers and delivers the whole line running, with a single point of contact for service.

Ease of cleaning defines how much real production time you get. An ultra-clean filling system has no moving parts or hard-to-reach areas, is self-draining and allows accurate filling without the valve touching the container, avoiding contamination. Its hydraulic design without dead zones prevents bacterial growth.

Clean-in-place (CIP) and sterilise-in-place (SIP) let you wash and sterilise the circuit without dismantling the machine, with superheated water or steam. In practice this cuts product changeover and washing down to a few minutes, even between very different products, and lowers the consumption of washing liquid. If you will alternate many products or colours, this point is decisive.

If you fill acids, chlorine, solvents or flammable products, safety and materials stop being a detail. The parts in contact with the product are selected for each application: AISI 316 stainless steel, PVC, titanium and EPDM, Viton or PTFE seals, to resist corrosion without contaminating the product.

For hazardous atmospheres, where the air may contain flammable vapours, there is the explosion-proof (Ex) configuration, with electrical and pneumatic installation designed for areas classified by regulation. It is not an optional accessory added later: it is best declared from the start of the project to size the equipment properly.

No catalogue figure replaces seeing the machine working with your own product. A testing bench lets you simulate real filling conditions, try different dosing nozzles and obtain a video with the productivity figures before deciding on the purchase. It is the safest way to avoid surprises.

Finally, think about the after-sales stage: availability of original spare parts, service response times, the option of remote assistance, and the ability to update the equipment in a few years without replacing the whole line. A machine built by a company that also provides the service and produces its own spare parts gives you support throughout the entire life of the equipment.

Not every plant needs the same level of automation. A manual or semi-automatic line can be the right decision when volumes are moderate, product variety is high or the initial investment is a constraint. An automatic line is justified when the volume is sustained and constant, and when the labour cost per container weighs more than the machine cost.

On drum fillers, for example, the manual version loads containers by forklift or pallet truck, while the semi-automatic one feeds them on a motorised roller conveyor and adds an infeed and outfeed buffer. The difference is not only speed: it changes the number of operators, the ergonomics and the traceability of the process. It is best to plan the level of automation around expected production growth, not just the present.

The purchase price is only a part of the real cost of a filling line. Over the years, what weighs far more is the product wasted through overfilling, the line downtime on each format changeover and cleaning, the consumption of water and washing liquid, and the cost of maintenance and spare parts.

A high-accuracy machine that overfills two grams less per container saves, across millions of containers a year, far more than the price difference against an imprecise machine costs. Likewise, a fast cleaning system (CIP/SIP) that recovers half an hour per product change frees real production capacity. When comparing quotes, it is worth translating each technical feature into its annual economic impact.

The most expensive mistake is sizing the machine only by the production average and not by the real peak: equipment pushed to its limit fails more and ages sooner. Another common mistake is not declaring from the start that the product is corrosive or flammable, and discovering later that special materials or an explosion-proof configuration are needed, which forces part of the project to be redone.

It is also common to choose thinking only about the current container and not about the formats the company will want to produce in a few years, ending up with a machine that falls short. And, above all, buying without having seen the equipment working with your own product: no datasheet replaces a real trial on the testing bench.

For the quote to be accurate and fast, it helps to arrive with these details defined. The more complete the information, the tighter the proposal.

The terms that come up most in a filling quote, one line each: