Nitrogen Purge Systems: Gas Versus Liquid

Nitrogen Purge Systems: Gas versus Liquid

We have had a good number of inquiries lately about nitrogen purge systems and the difference between a gas system and a system that uses liquid nitrogen.  So though we have covered this before, we wanted to post a quick refresher on the similarities and differences between the two.  In general, a nitrogen purge system will sit between the filling machine and capping machine on a packaging line, and the gas or liquid is used to displace oxygen either within the entire container or within the bottle headspace.  
Purge systems using nitrogen in a gaseous from are generally in service to remove the detrimental effects of oxygen on a product.  For example, some foods and beverages will spoil more quickly with oxygen present, depending on their ingredients.  Replacing the oxygen within the headspace of a filled container just before sealing the container can help to stop these detrimental effects.  By replacing the oxygen with nitrogen, a packager may extend the shelf life of a product, while also maintaining the the flavor, color and texture of the product for a longer period of time.  Obviously, the less waste produced by expired products and short shelf lives will influence a company's bottom line, making a nitrogen purge system an economical addition to a number of different packaging lines.
Liquid nitrogen is also capable of purging oxygen from the inside of a container, and actually turns into a gas immediately after being dispensed.  So of course, the obvious question is why is liquid nitrogen even necessary?   A liquid nitrogen doser will often be used before containers are filled, versus between the filling machine and capping equipment, to serve a completely different function from that of a gas purge system.  A liquid nitrogen dosing system can release liquid that not only turns to gas as it enters an empty container, but also expands when doing so.  The expansion creates pressure inside the bottle, which can add rigidity to certain containers, such as plastic bottles.  The end result is a stronger bottle, despite what might be a thin walled container.  Of course, the liquid nitrogen can also be used to extend the shelf life of a product as well, by displacing oxygen just as is done by the gas purge system.  
Whether a packager is interested in extending shelf life or adding rigidity to containers, a nitrogen purge system can be manufactured to work with existing packaging systems.  Machines can be manufactured to connect to a conveyor or can even be built with a portable frame to roll up to more than one packaging line per day.  For more information on how a purge system may benefit your own packaging process, or for more detailed information on the two different systems, feel free to contact one of our Packaging Specialists toll free at 1-888-393-3693.