Modified Atmosphere Packing Systems for Ridged Containers

Colby 3 Chamber Vacuumaster

Colby can supply a complete range of Modified Atmosphere Packing Systems (MAP) for retail packaged products.

We have different products and systems to provide low oxygen environments for sachets, sticks, pouches, cans, jars and bottles. Our systems can use a variety of mixed gasses to replace air and consistently achieve residual oxygen levels of less than 1%.

To do this Colby can use conventional post-gassing, in a Colby Vacuumaster, or use our latest pre-gassing technology.

GEA Colby have supplied more than sixty Colbe Vacuumaster Post-Gassing Machines, and twelve Colby Pre-Gassing Systems.  The advantages and disadvantages of each system are described below:

Post-Gassing

Post-gassing is the oldest and most common methos.  This process involves:

• Filling un-gassed powder into the can
• Clinching the end onto the filled can
• Removing air from the can in a vacuum chamber and replacing it with inert gas
• Seaming the end onto the can to produce a hermatic seal.

The main advantages and disadvantages of this process are:

• Requires a large, critical hygiene filling room
• Higher cost to construct and operate the filling room especially the HEPA air conditioning system
• Four (4) machines (filler, clincher, gassing chamber and seamer) to operate, to maintain, to clean and to change over to a different can diameter. Keeping machines free of dust is critical in the E. Sakazakii environment
• Lower inert gas consumption, typically 5-6 litres/kg of product for a 900 gram fill
• Higher electrical power consumption (more machines, especially vacuum pumps) and compressed air consumption
• Higher spare parts inventory.

Conventional post-gassing systems cannot be used for composite (paperboard body with metal ends) cans or plastic containers.

Pre-Gassing

Pre-Gassing is a much newer method. This process involves:

• Purging air from the empty cans using static gassing rail plenums
• Flushing the powder with nitrogren gas in the buffer hopper above the filler
• Filling cans in an inert environment
• Maintaining the inert environment from the filler to the seamer and until the end is seamed onto the can.

The main advantages and disadvantages of this process are:

• Requires a much smaller, critical hygiene filling room
• Lower cost to construct and operate the filling room especially the HEPA air conditioning system
• Two (2) machines (filler and seamer) to operate, to change over to another can diameter, to maintain and to clean
• Higher nitrogen gas consumption, typically 35-40 litres/kg of product
• Lower electrical power consumption and compressed air consumption
• Lower capital cost and lower labour operating cost
• Less machines means higher overall filling line efficiency
• Quicker and/or lower labour cost to change the line over to a different can diameter so higher line uptime
• Lower spare parts inventory

If only nitrogen gas is used the gas rail plenum is mounted above the can conveyor.

If a mix of nitrogen and carbon dioxide gasses are used then the gas rail plenum is inside a sealed tunnel, the filler enclosure is sealed and the seamer is in a sealed enclosure to prevent the carbon dioxide gas entering the filling room environment.

A pre-gassing filling line can handle three piece tin plate cans, composite cans (paperboard body with metal ends) and plastic containers.

To ensure reliable operation and good filling accuracy a filling machine needs a constant supply of powder and so it is normal practice to have a 0.5 - 2.0 m³ buffer hopper above the filler.

This is the same for both post-gassing and pre-gassing systems.

In a pre-gassing system this hopper has gassing elements to reduce the residual oxygen (RO) level in the can to less than 1.0%.

As the gassing rails are static they require very little maintenance and are easy to clean.

No change parts are required for the gassing rails and can height adjustments are made via an electric drive and take less than 5 minutes.

Utilities Consumption

For a system packing 900 gram cans at 100 cpm the estimated relative utilities consumptiosn of the two gassing and seaming systems for are typically:

Open Container Gassing

About 97% of all post-gassing systems use the conventional clinch / gas / seam process.

Jorgensen Engineering has supplied a small number of “Open Container” gassing systems. Some of these systems have been supplied to handle composite containers where a conventional system cannot be used.

In this system there is no clincher and the filled, open container is transported directly to the gassing machine. The open container is processed to the required RO level and is then transported to the seamer or sealing machine on conveyors that are housed in an inert gas tunnel.

The large gassing machine outfeed mattop accumulation conveyor is also housed in a sealed enclosure to prevent the open container from being exposed to the filling room environment.

In normal operation the filler would be cleaned daily to prevent even a film of powder building up on any part of the machine.

As the container is open during the entire loading/gassing/unloading cycle it is possible for small quantities of powder to be spilled from the container.

As the system uses mattop conveyors on the infeed, inside the vacuum chamber and the enclosed outfeed mattop conveyor we believe that cleaning these conveyors frequently would result in very high levels of filling line down time.

Post-Gassing System

Pre-Gassing System