Dear MOM,
Interesting question. It seems there are a variety of (geographical) standards involved, primarily (but not exclusively) relating to purity, ie max. levels of allowed “contaminants”.
The basic (food-grade) EC directive is probably this (2008) –
nitrogen - EC - l_25320080920en00010175.pdf 579.84KB
873 downloads
(For nitrogen see E941 ca pg157)
Other comments –
Requirements do vary from country to country concerning the specification for MAP gases.
For example, within Europe, the European Industrial Gases Association (EIGA), has developed a specification detailing the maximum contaminant levels acceptable for a gas to be considered food grade.
Nitrogen is classed as a food additive when it is in direct contact with the foodstuff and is designated an “E” number. The nomenclature for nitrogen is “E941”Compliance with the specified contaminant levels is mandatory under EU law.
PSA technology MAXIGAS nitrogen gas generators from Parker have been independently tested by an accredited UKAS scientific analysis laboratory to confirm that they fully comply, producing nitrogen gas, with residual levels well below EIGA’s specified maximums.In addition, the MAXIGAS materials of construction have been tested by the same UKAS laboratory to confirm full compliance with the United States FDA code of federal regulations title 21.
nitrogen - N2_FOOD.pdf 2.61MB
735 downloadsThe above mentioned EIGA compilation (2006) is here –
nitrogen - EIGA - Doc 126 06 E.pdf 178KB
499 downloadsAnd even further, eg -
All BIOGON®-products meet the requirements of the corresponding German and European food legislation. In particular this includes the European Regulations (EC) No. 852/2004, No. 1333/2008 and No.178/2002 as well as the Directive 2008/84/EC.
According to the german regulation about labeling of foodstuffs Lebensmittelkennzeichnungs-verordnung), gases of the product line BIOGON® do not contain allergens. In the production process no GMO-products are generated, applied or otherwise used.
nitrogen - db_biogon_n_liquid.pdf 302KB
346 downloadsVarious commercial products are offered with purities in excess of the above minimum criteria, eg see above attachs. and this –
nitrogen foodgrade - Linde - EN-PIB-0256.pdf 70.06KB
509 downloadsSo, reverting to yr original question, you would at a minimum require to get a validated analysis of the gas purity for comparison to the required chemical composition (eg E941) or yr own designated standard. Plus maybe some additional characteristics depending on yr local/specific requirements.
As an example of a possible reason to be cautious, can see this extract from an old but still readable compendium of food tips –
Locating a source of compressed nitrogen is probably as easy as looking in your local phone book under the headings "compressed gas suppliers", "gasses", or "welding supplies". Other sources might be automotive supply houses, university or college research departments, vo-tech schools, and medical supply houses.
Nitrogen is generally available in a number of forms ranging from gas intended for welding, to various purity assured types, to gas mixtures where N2 would be one of the components.
Unless you are very knowledgeable about compressed gasses and the equipment needed to use them it is strongly recommended that you not use any gas mixtures in your food storage, but rather to stay with pure nitrogen gas. Use of compressed gas mixtures requires knowledge and equipment beyond the scope of this FAQ.
IMPORTANT NOTE: Welding nitrogen is essentially a pure gas, but it has one important caveat. When a cylinder of welding gas is used there is an unknown possibility that some form of contaminant may have backfed into the cylinder from a previous user. Possibly this could happen if the tank was being used in an application where the cylinder's internal pressure fell low enough for pressure from whatever the tank had been feeding to backflush into the cylinder. Alternatively, the tank pressure may have become depleted and was repressurized using ordinary compressed service air. The most likely contaminants will be moisture, carbon monoxide, carbon dioxide, oxygen and hydrocarbons, but there is the remote possibility of something even more exotic or toxic getting into your cylinder. Welding gas cylinders may not be checked by the gas supplier before being refilled and sent back out for use. It is this remote, but unknown possibility of contamination that causes me to recommend against the use of welding grade nitrogen in food storage. If your supplier is willing to certify that welding gas cylinders are checked before refilling then they would be OK to use.
The varying types of purity assured nitrogen gas are slightly more difficult to find and slightly more expensive in cost, but I believe this is more than made up for by the fact you know exactly what you're getting. Air Liquide, as an example, offers seven types of purity assured nitrogen ranging from 99.995% to 99.9995% pure with none having a water vapor content over 1 part per million (ppm) or an oxygen content over 3 ppm. Any of them are eminently suited to the task so the most inexpensive form is all you need buy.
Nitrogen (Various Factors in Food Storage) FAQ_3_5.pdf 534.62KB
492 downloadsRgds / Charles.C