Safe Use of Liquid Nitrogen in Food Processing Plants

 

In December 2020,  two employees working at a Vernon, California food processing plant lost consciousness and died following an apparent liquid nitrogen leak. On January 28, 2021, there were several fatalities, and many other employees became sick, after being exposed to nitrogen gas when a liquid nitrogen line ruptured at a food processing plant in Gainesville, Georgia.According to the Occupational Safety and Health Administration (OSHA), a total of fourteen workers died from asphyxiation linked to nitrogen gas in twelve separate workplace accidents recorded between 2012 and 2020, and 2021 is already off to a sad start.  Tragically, these accidents illustrate the dangers of working with liquid nitrogen.

Importance of Liquid Nitrogen in Food Processing

Liquid nitrogen (LN2) is used in food processing in a number of applications, including grinding, mixing, coating, freezing, and packaging foods. Food processors may use liquid nitrogen in the production of a variety of foods, such as meat, poultry, seafood, fruits, vegetables, baked goods, and prepackaged meals. The very low temperature of LN2 is used to flash-freeze foods to help prevent microbial growth that can lead to food spoilage, and to maintain the foods’ original freshness, flavor, and textures.

Oxygen Monitors Can Reduce the Risk of Liquid Nitrogen Accidents

While the use of liquid nitrogen is important in food processing, it is not without risk. When liquid nitrogen is exposed to the air (which happens when leaks occur), it will evaporate, changing from a liquid to an oxygen-depleting gas. Oxygen deprivation can put employees in real danger if there are leaks from pressurized LN2 freezer lines, exhaust systems, or on-site storage containers. In the event of a liquid nitrogen leak, food processing workers could become disoriented, lose consciousness, or even suffocate from breathing oxygen-deficient air. Since LN2 is both odorless and colorless, workers would, in the absence of appropriate monitoring, have no way of knowing that there has been a liquid nitrogen leak.

However, by utilizing a top-quality oxygen deficiency monitor, food plant personnel can safely track oxygen levels and detect leaks before workers’ health is jeopardized.Best practice calls for oxygen deficiency monitors to be installed anywhere there is a risk of liquid nitrogen gas leaks. The monitor should be placed wherever liquid nitrogen is stored, and in all areas where liquid nitrogen is used. The monitoring equipment should include visual and audible alarms that would be activated in the event of liquid nitrogen leaks and a decrease in oxygen levels.

PureAire Monitors

PureAire Monitoring Systems’ line of oxygen deficiency monitors, including a water-resistant unit for facilities requiring daily wash-downs, offers thorough air monitoring, with no time-consuming maintenance or calibration required. In the event of a liquid nitrogen leak, and a decrease in oxygen to an unsafe level, PureAire’s oxygen deficiency monitor will set off an alarm, complete with horns and flashing lights, alerting personnel to evacuate the area. PureAire oxygen deficiency monitors are ideally suited for use in food processing facilities because the monitors can withstand temperatures as low as -40 Celsius. Each PureAire O2 monitor has an easy to read screen, which displays current oxygen levels, for at-a-glance reading by food processing employees, who derive peace of mind from the monitor’s presence and reliable performance.

The Benefits of Nitrogen and Carbon Dioxide for Food Processing

A blend of gases -- carbon dioxide, oxygen, and nitrogen -- help preserve packaged food by reducing the amount of oxygen inside the sealed package. Gas flushing or Modified Atmosphere Packaging, as the process is called, also reduces the amount of processing that food must undergo. This preserves the quality and nutrient content of meats, vegetables, and other foods.

Estimates suggest that 25-40 percent of fresh food does not reach consumers due to spoilage in transit. Modified Atmosphere Packaging enables fresh food to stay fresh by slowing down the food spoilage process, reduces food waste, and allows consumers to store purchased foods for longer. 

Without Modified Atmosphere Packaging, oxygen levels inside food packages would be 20.9 percent. By introducing nitrogen into the package, facilities strive to lower oxygen levels, sometimes as far as zero. With no oxygen inside the package, bacteria will be unable to grow and the food will not oxidize. Carbon dioxide also inhibits bacteria growth and lowers the pH of preserved food. Carbon monoxide is often used in meat packaging, as it can preserve the red color. Packing plants use either low-barrier, breathable film that allows fruits and vegetables to breathe, or high-barrier film that prevents gas inside packaged meat, fish, or cheese from seeping out. 

As oxygen is flushed out of the package, the blend of nitrogen and carbon dioxide or carbon monoxide is piped in and the package is sealed, trapping the inert gases inside.

While the process of Modified Atmosphere Packaging revolutionized food packing, it isn't without risk. Nitrogen gas, a critical component of the gas flushing blend, has the potential to create an oxygen deficient environment if a leak occurs. As nitrogen leaks, it physically displaces oxygen, often in a matter of minutes. As employees breathe air that does not have enough oxygen, they may become tired and confused or experience difficulty breathing. Within minutes, employees could die from asphyxiation as a result of breathing oxygen-deficient air. 

Since nitrogen gas has no color or odor, secondary measures must be used to detect a leak before staff experience life-threatening symptoms. One simple and cost-effective way to monitor the food packing facility for leaks is by using an oxygen monitor. 

How an Oxygen Monitor Protects Workers in Food Packing Plants

While it's critical to maintain the right blend of gas in packaged foods, it's also important to ensure that gas used in food packing equipment does not leak out of the machines. Gases used in food packing, including nitrogen, are colorless and odorless, so staff would be unable to detect a leak visually. By installing an oxygen monitor in the food packing facility, employers can detect leaks before workers' health is adversely affected. 

Since nitrogen gas depletes oxygen, it's easy to tell whether nitrogen is leaking by taking continual measures of oxygen. The secure, wall-mounted oxygen monitor checks the levels of oxygen in the room and remains silent as long as oxygen is above the minimum amount. 

The oxygen monitor will sound an alarm if oxygen falls to 19.5% or 18.0%. The 90 db alarm is designed to be heard over the sound of the equipment, and there's also a flashing light to warn employees of a drop in oxygen levels. Employees can then leave the room before the oxygen falls below the acceptable threshold and staff begin to experience health problems. 

In addition to using oxygen monitors on the food packing line, facilities should also use oxygen monitors wherever inert gases are stored. Oxygen deficiency monitors from PureAire are designed to last for a minimum of 10 years with no maintenance or annual calibration. The monitors feature a digital display that's easy to read, and do not drift as a result of barometric pressure. If you're looking for an oxygen monitor that's low maintenance, accurate, and easy to use, consider PureAire. Visit www.pureairemonitoring.com to learn more.