Nitrogen

Nitrogen (N₂, LIN ₂)

Nitrogen constitutes 78 percent of the atmosphere and is a constituent of all living tissues. It has two characteristics that make it the world’s most widely used gas. Liquid nitrogen is intensely cold. This makes it a highly effective (and totally non-polluting) agent for freezing and chilling. Nitrogen is also inert; under normal conditions it is not chemically active. An atmosphere of nitrogen is like a blanket that prevents oxidation and combustion from taking place. Gaseous nitrogen at atmospheric pressure has no taste, color, or odor. It’s a poor conductor of heat and electricity, and has low solubility in most common liquids. Nitrogen has no toxic properties at atmospheric pressure, other than the possible hazard of suffocation due to displacement of air.

At -320° F (-196° C) and standard atmospheric pressure gaseous nitrogen condenses into a water-white liquid, with 696.5 volumes of gaseous nitrogen becoming one volume of the liquid. The liquid is non-magnetic, stable against mechanical shock and does not produce toxic or irritating vapors. The only caution required in handling liquid nitrogen is due to its low temperature.

Liquid nitrogen is classified as Type II by the Compressed Gas Association (CGA). CGA-10.1, Type II Grade L or The National Formulary Specs (similar to USP) are considered “commercial” liquid nitrogen standards.

Large volume gaseous nitrogen requirements are met by vaporization of liquid on-site from a suitable liquid storage container. Smaller volumes of CGA Type I gaseous grades meeting any of the Compressed Gas Association’s grade requirements are supplied in various high pressure containers ranging from cylinders to tube trailers.

Safety

Nitrogen is an inert gas which cannot be sensed by odor, color, or taste. It is difficult to know when nitrogen is present and when it may be depleting oxygen for breathing. It must be used in well-ventilated areas. Efforts must always be made to avoid leaks or venting of these gases in confined spaces. Do not work with any inert gases in confined spaces such as tanks, pits or tunnels unless an adequate breathing air supply is available. Always provide good ventilation in enclosed areas where inert gases may be present.

Liquid or cold gas nitrogen can cause frostbite-type burns. Protect eyes and skin from exposure to these low temperature materials. Wear protective goggles, gloves, and clothing where cold liquid might be spilled.