Combiblock for 5 L and Large-format Bottles (3–16 L)

1. What changes when the bottle passes 3 L

Large-format bottling is not small-format bottling running slowly. Above roughly 3 L a different set of physical limits takes over, and each one pushes output down and cost per bottle up. Buyers who scale a 12,000 BPH water quotation down to a 5 L bottle and expect the same machine at a lower price are working from the wrong model.

• The preform is heavy. More material to heat evenly, and a thick wall that takes longer to cool once blown.
• The dose is large. Filling 5 L through a practical valve takes several seconds, not a fraction of one.
• The bottle cannot be air conveyed. Above about 2 L, empty containers travel on slat conveyors carried by their base.
• Handles enter the design. Anything a customer carries one-handed needs a grip, and that grip is a manufacturing decision.
• Packing changes shape. Fewer units per layer, fewer layers per pallet, and top load becomes a live constraint rather than a formality.

A combiblock still earns its place here, but for a different reason than on small-format water. There the saving is in bottle weight and the deleted air conveyor. Here the saving is in the empty-bottle handling that large containers otherwise force on you: a long slat conveyor run, an accumulation table sized for containers that occupy real floor area, and in many plants an empty-bottle store.

2. Preform, mould and the blowing cycle

A 5 L still water bottle sits indicatively in the 80–120 g band, with 10–16 L containers running considerably heavier. That weight is not simply five times a small bottle; it is set by the top load the pack has to survive and by how the container behaves when a customer lifts it full.

2.1 Heating

Preform heating time rises sharply with wall thickness, because heat has to reach the core without overheating the surface. Practically that means a longer oven with more lamp modules, a slower preform speed through it, or both. It also means the heating profile is less forgiving: a heavy preform that is hot outside and cold inside produces uneven wall distribution that shows up as a soft panel or a thin base.

2.2 Cooling in the mould

The blown bottle must be held against the cooled cavity until the wall is dimensionally stable. Thicker walls need longer, and that time cannot be bought back with a bigger machine — only with more cavities. Chilled water capacity and flow through the mould matter more here than on small formats, and an undersized chiller is a common reason a large-format line never reaches its rated output.

2.3 Cavity count and clamping

Large bottles need large cavities, which means fewer of them across the same clamp and a higher clamping force per cavity. This is why the cavity count on a large-format block is a small number, and why the step from 3 L to 10 L is a machine change rather than a mould change.

3. Handles: three ways to give a big bottle a grip

Anything above about 3 L is carried, not just picked up, and the handle decision affects the machine as much as the bottle.

For a combiblock the clip-on route is usually the pragmatic answer, because it leaves the blowing station alone. The trade-off is a bought-in component on every bottle, which at high volume is a genuine cost line. Decide it with the bottle drawing, not afterwards.

4. Filling time is what sets the valve count

The number of filling valves on a large-format machine surprises buyers. The arithmetic is straightforward and worth doing before reading any quotation.

1. Start from the dose time. How many seconds does one container take to fill at a flow rate the product and the neck opening allow, including the slow-down at the end to hit the level or weight?
2. Convert to a carousel period. Only part of one revolution is available for filling — the rest is infeed, transfer and outfeed. Assume roughly 60–70% of the revolution is usable, so the revolution period is about the dose time divided by 0.65.
3. Convert to a valve count. Each station handles one container per revolution, so valves ≈ bottles per hour × revolution period in seconds ÷ 3,600.

Treat the table as a sizing method rather than a specification — real dose times depend on valve type, neck opening, product and how much foaming can be tolerated. The point it makes is structural: a 5 L machine needs roughly three times the valves of a 0.5 L machine to reach the same bottles per hour, and every valve is cost, weight and carousel diameter. This is the real reason large-format lines are quoted at lower outputs.

5. Weighing or volumetric — choosing the valve

Four valve families appear on 3–16 L work and the choice is genuinely open, unlike small-format water where the cheapest option usually wins.

The decision rule is about absolute quantity, not percentage. A 0.5% error on 0.5 L is 2.5 ml and nobody notices. The same 0.5% on 10 L is 50 ml given away or short-filled on every container, and at large-format volumes that adds up quickly in either direction. That is why load cell filling, which is hard to justify on small water bottles, becomes a reasonable purchase above 5 L. Full comparison in load cell vs volumetric vs mechanical filling valve.

6. Capacity bands and what limits them

Within each band, the top figure belongs to the smallest bottle in the band and the bottom figure to the largest. A machine quoted for 3–7 L will not hold its 3 L rate on a 7 L container. State the size mix you actually intend to run, in the proportions you intend to run it, because a line specified on the smallest format and then loaded with the largest will miss its plan. Sizing method across the whole range is in combiblock capacity selection, and the comparable small-format page is combiblock for still water.

7. 5 L home pack and 19 L returnable are different businesses

These two are constantly confused at enquiry stage, and the confusion wastes weeks.

7.1 Single-trip 3–16 L

A new PET bottle is blown, filled, capped and sold. The container is part of the cost of goods and is discarded or recycled by the consumer. Everything in this article applies. The commercial pressure is on bottle weight and on pack cost, because the container is bought fresh with every sale.

7.2 Returnable 19 L / 5-gallon

The container circulates. The line is built around reconditioning it: decapping, external washing, internal washing and rinsing, inspection for residue and odour, then filling and capping. Container purchase is a one-off capital item amortised over many trips, and the operating cost sits in washing, in losses and in logistics. A 19 L line and a 5 L line share the filling principle and almost nothing else — see the 19 L / 5-gallon line overview.

8. Downstream, and how to choose

8.1 Conveying and packing

Filled large-format bottles are heavy and comparatively unstable, so conveyor width, chain selection and speed all change. Packing usually means shrink film with or without a tray, in small counts — frequently four or six units — and the film has to tolerate handles if handles are fitted. Palletising is lower and wider than on small formats: fewer units per layer, fewer layers, and a pallet pattern that has to be agreed with your distribution before the palletiser is specified.

8.2 Top load

Top load is where lightweighting stops on this format. The bottom bottle in a stack carries everything above it through a warehouse summer, and the pack has to survive it. Test to your own stacking height and your own climate rather than to a generic figure.

8.3 A short decision sequence

1. If the container is single-trip PET below about 7 L, then a combiblock removes the empty-bottle conveying and storage that this format otherwise forces on the layout.
2. If the container is returnable, then you need a washing line, and blowing is irrelevant.
3. If the declared quantity is volume and the format is 3–7 L, then a volumetric valve is normally sufficient.
4. If containers are 5 L and above, or sold by mass, then price the load cell configuration and compare absolute give-away, not percentage accuracy.
5. If a handle is required, then settle the handle route with the bottle drawing, because it decides whether an extra machine enters the line.
6. If you also run small formats, then plan two lines rather than one compromise machine.

Sunswell has delivered multi-line programmes covering several formats, including eight bottling and canning lines for Rauan in Kazakhstan at 12,000–24,000 output levels, and builds mechanical, volumetric and load cell fillers across the 3–15 L range. Configuration and investment levels are compared in still and mineral water configuration comparison, with the full selection method in the water machine selection guide.

Frequently asked questions