LF Liquid Filling Machine

Filling a container, step by step

The empty container is placed on the 400 × 400 mm weighing platform and positioned under the filling nozzle. If net filling is selected, the machine first tares the container; in gross mode container and contents are targeted together. The valve then opens wide and the container starts filling in the fast stage. As the weight approaches the target, the valve throttles back, the last portion is completed in the slow stage and flow is cut at the target value. The container is lifted off and the next one takes its place.

The point of two stages is this: with a single-speed valve you sacrifice either speed or accuracy. On the LF the bulk of each fill goes in quickly, which keeps the cycle short, while the last grams arrive at a low rate so filling stops without overshooting. Weight is followed with a 10 g resolution; on a 20 kg tin, for example, that is a reading step of about one two-thousandth of the target.

Which containers suit the LF?

In the standard configuration the container is defined as at most 400 mm in diameter and 500 mm high; the weighing platform is 400 × 400 mm and the maximum capacity is 30 kg. These dimensions cover the tins used for paint and varnish, 20-litre jerrycans and pails. When the fill weight drops below 10 kg or the container exceeds these dimensions, a 200-litre drum for instance, the platform and capacity have to be reviewed for your container. That is why we ask for container size and fill weight together before quoting.

With a narrow-neck jerrycan, the nozzle has to fit into the neck without effort and the lightweight plastic container must not shift during filling; with a wide pail, the liquid should go in without splashing. These points are about the fit between container and nozzle rather than the machine itself, and they are set up for your container during installation.

What does the hourly output depend on?

The LF’s filling rate is given as 120–240 containers per hour, which works out at roughly a 15–30 second cycle per container. Three things decide whether you run near the top or the bottom of it: how runny the liquid is, the fill weight and how quickly containers are put on and taken off the platform. With a water-thin product the fast stage is short; a thick filler paint takes longer to fill the same container.

A quick example helps you size your need: filling 180 tins of 20 kg an hour means 3.6 tonnes of product an hour. If your daily target is 25 tonnes in an 8-hour shift, that is about 3.1 tonnes an hour, or 156 containers of 20 kg an hour, which sits inside the range. If the target goes beyond 240 containers, a second station or a container feed arrangement should be discussed.

Installation site and utilities

The LF runs on electricity and compressed air. Air pressure must be in the 0.4–0.8 MPa range (about 4–8 bar); if your plant has no compressed-air line, it has to be added to the installation plan. Power supply is AC 110 V or 220 V, 50/60 Hz. The operating temperature range is −10 °C to 40 °C; keep this in mind if the station will run in an unheated warehouse or a hot filling area in summer.

For stable readings, the weighing platform should stand on a solid floor free of vibration. Shaking from pumps, mixers or forklift traffic directly affects accuracy at the end of the fill, so the station is placed away from such sources where possible. Setting each container down in the same spot on the platform also improves repeatability; a simple mark or guide on the platform is usually enough for this.

Valve material and the Ex-proof option

The filling valve is chosen in AISI 304 or AISI 316 stainless steel. As a rule, 304 is sufficient for food liquids and products with low corrosivity; for products containing salt or chlorides, or more aggressive chemicals, molybdenum-bearing 316 is preferred. Telling us the chemical make-up of your product is enough to pick the right material.

If solvent-based paint, thinner or similar hazardous substances are filled, the LF is configured with the Ex-proof option. In that case you need to state the plant’s hazardous-area zone at the quotation stage; the equipment is chosen on that basis.