Gas monitoring is critical in frozen food storage and processing facilities because gases such as carbon dioxide (CO2), nitrogen (N2), liquid nitrogen (LN2), and ammonia (NH3) can create hazardous conditions if they leak, accumulate, or are released in an enclosed or poorly ventilated area.
Many of these gases cannot be reliably detected by sight or smell. A leak from a refrigeration system, compressed gas cylinder, storage tank, supply line, cryogenic freezer, or processing equipment can expose workers to elevated gas concentrations or create an oxygen-deficient atmosphere.
Continuous gas monitoring provides an early warning so employees can respond to potentially hazardous conditions before exposure becomes dangerous.
OSHA and NIOSH CO2 Exposure Limits
Carbon dioxide is colorless and odorless, which makes direct CO2 detection especially important in facilities where significant quantities of CO2 are used or stored.
OSHA establishes a permissible exposure limit (PEL) of 5,000 ppm CO2 as an 8-hour time-weighted average (TWA).
NIOSH recommends:
- 5,000ppm as a time-weighted average exposure limit
- 30,000ppm as a short-term exposure limit (STEL)
- 40,000ppm as Immediately Dangerous to Life or Health (IDLH)
These values represent different types of occupational exposure limits and should not be interpreted as interchangeable alarm setpoints. Gas detector alarm settings should be established according to applicable regulations, codes, manufacturer recommendations, and the facility's specific safety requirements.
Oxygen Deficiency in Cold Storage Facilities
Nitrogen, liquid nitrogen, and other gases can also create an oxygen-deficiency hazard by displacing normal atmospheric air.
OSHA defines an oxygen-deficient atmosphere as one containing less than 19.5% oxygen by volume.
This can be a particular concern in enclosed areas such as cryogenic freezing rooms, cold storage areas, laboratories, and processing spaces where nitrogen or other inert gases are used.
An oxygen deficiency monitor continuously measures the oxygen concentration and can alert personnel when O2 levels fall below configured safety thresholds.
CO2 Monitoring vs. Oxygen Deficiency Monitoring
It is important to understand that an oxygen deficiency monitor is not a substitute for a CO2 monitor when carbon dioxide is the primary hazard.
A CO2 concentration can become hazardous before enough oxygen has been displaced to activate a typical low-oxygen alarm. Therefore, facilities using significant quantities of carbon dioxide should evaluate the need for direct CO2 monitoring rather than relying solely on oxygen deficiency detection.
Similarly, areas where nitrogen or other inert gases present the primary displacement hazard may require oxygen deficiency monitoring.
The correct gas detection strategy truly depends on the gases present, potential leak sources, room volume, ventilation, equipment layout and facility-specific risk assessment.
Common Gases in Frozen Food Storage and Their Risks
- Liquid Nitrogen (LN2) is often used for quick freezing of food products known as cryogenic freezing. It has an extremely low boiling point of -196° degrees Celsius (-321° degrees Fahrenheit), making it highly effective for rapidly reducing the temperature of food.
- Nitrogen (N2) is used in several ways in the frozen food industry, for inert gas blanketing to displace oxygen and create a protective atmosphere in food packaging and to prevent oxidation. With the use of nitrogen, food manufacturers can preserve and maintain food quality as well as increase the shelf life of fresh food.
- Carbon Dioxide (CO2) can be used as a refrigerant in modified atmosphere packaging (MAP) to control the gas composition or to extend the shelf life and preserve product quality. It can also be used to carbonate frozen beverages and add flavor to carbonated products. Further, CO2 is also used as dry ice for food refrigeration in transit and short-term storage.
- Oxygen (O2). While oxygen is not used in frozen food processing, its exclusion through modified atmosphere packaging or inert gas blanketing helps prevent oxidation and maintains the quality of frozen products.
- Helium (He). Although less common, helium can be used in cryogenic cooling and freezing applications. Liquid helium is extremely cold and non-reactive, making it suitable for specific freezing processes. However, it's recent scarcity has limited its use in food preservation.
- Ammonia (NH3) is used in many industrial refrigeration systems for maintaining low temperatures in storage and transportation of frozen food products. However, it is highly toxic and flammable. In addition, long-term exposure can lead to irreversible side effects.
Which Frozen Food Storage Applications use Gas?
Food production, preservation, flash freezing and transportation involve many industries and are applied to a wide range of food products. Below we highlight some of the industries in food production that utilize preservation, cold storage, freezing, and transport using gas.
Modified Atmosphere Packaging
Modified atmospheric conditions are now commonplace in the packaging, storage, and transport of all kinds of food products, from fresh to frozen produce. High carbon dioxide and reduced oxygen levels are used to slow spoilage, to kill insect species, and to limit microorganisms that would otherwise grow on stored foodstuffs.
High nitrogen concentrations can additionally be used as a humidity control for dried foods as it can help preserve food quality while extending lifetime. By using gas mixtures to replace insecticides, and the addition of preservatives such as nitrites to meats, modified atmosphere packaging offers a versatile way to preserve foods without the need to add additional chemicals or processing.
Beverage Industry
The carbonation of beverages, such as soft drinks, sparkling water, and beer, involve the use of carbon dioxide (CO2) gas to create effervescence. In addition, nitrogen can also be used to give a frothy texture to certain beverages, such as stout beer or nitro coffee. Blanketing with gases, usually nitrogen, can be used in addition to create a protective atmosphere above the liquid in storage tanks.
Baking and Pastry Production
In the baking and pastry industry, carbon dioxide is produced to help dough rise, resulting in baked goods like bread, cakes, and pastries with a light, airy texture. When fillings or toppings, such as those in quiches, expand and set during baking, gas production can also play a role in the desired texture or appearance. Nitrogen is also for cooling, chilling, and food freezing.
Dairy Industry
The dairy industry uses gases in various applications, including the injection of nitrogen gas into milk to remove oxygen, extend shelf life, and preserve the flavor and nutritional quality. Gases may also be used to control the temperature and humidity in dairy storage facilities, ensuring that dairy products are stored in the appropriate conditions to maintain their quality and safety.
Freezing and Cryogenic Cooling
Gases such as liquid nitrogen (LN2) are used for rapid freezing and cryogenic cooling in various food industries to preserve the quality of products during the freezing process. This process involves lowering the temperatures of food to a point where most of the water in the food turns to ice. Freezing also prevents microbial growth and enzymatic activity that can spoil the food. There are different methods of freezing, such as air-blast freezing, contact freezing, and cryogenic freezing.
Animal Processing and Euthanasia
The euthanasia of livestock in poultry farms, in dog pounds and in animal testing labs can use carbon dioxide to stun animals before slaughter. CO2 induces unconsciousness and alleviates pain and distress.
Food Distribution and Transportation
Transportation and delivering of food products to consumers, retailers, or end users requires maintaining the "cold chain," a system of refrigerated storage and transportation that ensures the food remains safe throughout its journey. For example, nitrogen is often used to create an inert atmosphere during food storage that prevents oxidation and microbial growth.
Canning and Food Preservation
Gases such as nitrogen can be used to create a protective atmosphere in canned food products to prevent oxidation and maintain product quality. In the canning process, inert gases like nitrogen are used to displace oxygen within the cans before sealing. This inert gas blanket prevents the oxidation of the food, which can lead to spoilage, off-flavors, and color changes.
Frozen Food Compressed Gas Hazards
Within food production and manufacturing there are several sub-industries we previously touched on, all that use compressed gases as an essential component of their day-to-day process. The use of these compressed gases can present various hazards, and it’s essential to manage these risks by use of gas safety monitoring to ensure the safety of both workers and consumers.
Common hazards associated when using compressed gases include pressure, asphyxiation, convulsions, toxicity and inadequate ventilation. Because gases are stored at such high pressures, if not properly handled, they can lead to ruptured containers, leaks, or even explosions.
Workers in the food production, preservation, and chilling industries may often be at risk of injury from flying debris or the force of the gas release. In addition, some gases used in food production, like nitrogen and carbon dioxide, can displace oxygen in confined spaces. This can lead to inadequate ventilation, oxygen deficiency, or pose a risk of asphyxiation to workers and those near gas hazard points.
For some gases that react with food products or other substances in the production environment, they too can also lead to potential negative health effects or chemical reactions due to hazardous byproducts. This can further affect food quality, product, and overall safety for the consumer and end user. To mitigate these hazards, it is critical to follow strict safety procedures when dealing with compressed gases and be able to mitigate hazards before they occur.
Below we highlight the main hazard locations you should know when working near or around dangerous compressed gases in the field.
- Cold Storage Areas: Cryogenic gases like liquid nitrogen are used for rapid cooling and freezing of food products. These gases can be extremely cold and can cause frostbite or cryogenic burns if they meet skin or eyes. These areas can present fire safety concerns. For instance, a fire broke out at Buffalo Farms Freezer and Cold Storage, a fruit-packing and storage warehouse in Hammonton, New Jersey, which reportedly started from hot work activities taking place at the facility.
- Post-Lethality Region: After thermal processing, food products are typically exposed to the environment prior to freezing in an area commonly referred to as the post-lethality region. This area is a critical component of Listeria monocytogenes control.
- Gas Supply and Storage Areas: The area where compressed gas cylinders are stored and maintained can be dangerous if not managed properly. Leaking cylinders, improper storage, and mishandling pose risks to workers in this area.
- Food Production and Packaging Line: The use of compressed gases for modified atmosphere packaging is common. These gases can be used inside the food packaging yet when altered, can carry risks associated with the handling and storage of these gases. Gas leaks or incorrect gas mixtures can affect product quality and safety.
- Laboratories and Quality Control: Food production facilities often have laboratories for quality control and testing. Some of these labs may use compressed gases for various analytical processes, and potential hazards must be managed in these areas.
- Food Transportation and Handling: The transport and handling of compressed gas cylinders to and from various areas in a food production facility poses risks if not done carefully. Falling cylinders can cause injuries, leaks, and damage.
To mitigate risks in these areas, food production facilities should implement safety measures, including proper training, the use of appropriate gas safety monitoring, personal protective gear, regular inspections, and overall adherence to safety standards. Additionally, facilities should conduct risk assessments and emergency response planning to address potential compressed gas hazards effectively.
What Gas Detectors are Needed in a Cold Storage Facility?
The gas detectors needed in a cold storage or frozen food facility depend on the gases used in the refrigeration, freezing, packaging and storage processes.
Facilities using carbon dioxide may require CO2 monitors, areas using nitrogen or liquid nitrogen may require oxygen deficiency monitors, and facilities with ammonia refrigeration may require NH3 detection. Some facilities may need multiple types of gas detection to address different atmospheric hazards.
To minimize downtime and spoilage while protecting people:
- CO2 Monitoring: Use fixed CO2 storage safety alarms near cylinders, evaporators, floor-level low points, and return-air paths.
- O2 Deficiency Monitoring: Install oxygen depletion alarms in rooms using LN2 or N2 blanketing (MAP lines, spiral freezers, cryo tunnels).
- Ammonia (NH3) Detection: Position toxic gas sensors in machinery rooms and potential leak sources; integrate to auto-ventilation and emergency shut-off.
Depending on the monitoring system and facility design, fixed gas detectors may also use relays to:
- Activate mechanical ventilation or exhaust fans
- Trigger horns and strobes
- Close gas supply valves
- Send signals to a building or fire alarm system
- Provide remote warnings outside a potentially hazardous room
Portable gas detectors can provide an additional layer of protection for workers who move between areas, perform maintenance, transport dry ice, or conduct atmospheric testing where fixed detection is unavailable.
Why Gas Monitoring is Crucial for Frozen Food Storage Facilities
To provide further perspective, there have been numerous accidents involving gas leaks that have been reported worldwide, hospitalizing hundreds, and even resulting in fatalities.
Typical gas leak accidents involve system wear or failure of components, lack of preventative maintenance guidelines, and lack of gas detection solutions.
For frozen food production and preservation, only a gas safety monitor or a analyzer can help mitigate hazards, maintain preservation of product and ensure employee safety for your staff and establishment.
Because gases like CO2 are so dangerous and can’t be detected by the human eye, the National Institute for Occupational Health and Safety (NIOSH) has put standards in place. These standards state that CO2 levels of 40,000ppm (4%) are immediately dangerous to life and health within 10-hour workplace exposure limits.
In fact, due to such severe incidents around the globe, the Occupational Safety and Health Administration (OSHA) has put together a list of standards for businesses to abide by when entering confined or potentially oxygen deficient spaces.
These standards state, “For any employee who must enter a confined space or potentially oxygen deficient space may require a low oxygen deficiency alarm, a respirator, or personal protection equipment." OSHA also defines an oxygen deficient atmosphere, as any atmosphere where less than 19.5% oxygen is found by volume. At lower levels, severe negative health effects can occur as follows:
It’s a popular myth in the industry that monitoring for low oxygen levels will give an appropriate carbon dioxide reading. The reality, however, is that carbon dioxide can escalate to danger before any oxygen sensor would ever alarm, because CO2 settles first at the floor and oxygen sensors are most typically mounted at eye level.
Like NIOSH, OSHA also sets a current standard for those working, using, or storing hazardous carbon dioxide gases. The current OSHA standard is 5000 ppm as an 8-hour time weighted average (TWA) concentration. Concentrations of 10 (100,000 ppm) or more can further produce unconsciousness, seizures, and even fatality.
Normal levels of CO2 in fresh air are approximately 400 ppm (parts per million) or 0.04% CO2 in air by volume. The table below shows the effects of increased CO2 levels in an enclosed space as a percentage of air by volume.
Read the complete list of OSHA, NIOSH and other CO2 standards here.
Overall, when it comes to hazardous gases like nitrogen, oxygen, ammonia, and carbon dioxide; extreme exposure can be fatal. If a canister or supply line begins to leak, gas will soon enter the entire facility or if a fitting is loose, this can mean severe danger for anyone in the establishment. When this happens, hazardous gas can displace the air and since no one can tell of the leak, only a real-time gas safety monitor can indicate that danger is near.
These gas leaks, as unfortunate as they are, are common in enclosed spaces such as food production rooms, freezers, processing lines, and chillers. The easiest way to protect employees’ safety is by installing a gas safety monitor to track gas levels, sound an alarm, and warn all employees near potential leak points. These safety monitors operate by tracking gas concentrations in real-time, sounding an alarm for high concentrations, and ensuring peace of mind for your staff, employees, and establishment.
Frequently Asked Questions About Gas Safety in Frozen Food Storage
What gases are commonly used in frozen food storage facilities?
Frozen food production and storage facilities may use carbon dioxide (CO2), nitrogen (N2), liquid nitrogen (LN2), ammonia (NH3), oxygen (O2), and other gases for refrigeration, freezing, packaging, preservation and transportation. The specific gases used depend on the refrigeration system and food-processing application.
Why is gas monitoring important in cold storage facilities?
Gas monitoring helps detect hazardous gas concentrations before workers are unknowingly exposed. Refrigerant leaks, cryogenic gas releases and compressed gas leaks can create toxic, high-CO2 or oxygen-deficient atmospheres. Fixed gas monitors provide continuous measurements and can activate audible and visual alarms when configured safety thresholds are reached.
What gases should be monitored in a walk-in freezer or cold room?
The appropriate gas monitor depends on the gases and refrigeration systems used in the facility. Areas using CO2 should be evaluated for carbon dioxide monitoring, while areas using nitrogen or liquid nitrogen may require oxygen deficiency monitoring. Facilities using ammonia refrigeration should evaluate the need for ammonia gas detection.
Can liquid nitrogen cause oxygen deficiency?
Yes. Liquid nitrogen rapidly expands into nitrogen gas as it warms and vaporizes. In an enclosed or inadequately ventilated area, released nitrogen can displace normal atmospheric air and lower the oxygen concentration, creating a potentially dangerous oxygen-deficient atmosphere.
What oxygen level is considered oxygen deficient?
OSHA defines an oxygen-deficient atmosphere as one containing less than 19.5% oxygen by volume. Facilities using nitrogen, liquid nitrogen or other gases capable of displacing oxygen should evaluate whether oxygen deficiency monitoring is appropriate for their application.
Can CO2 become dangerous before an oxygen monitor alarms?
Yes. A carbon dioxide hazard should not be monitored solely with an oxygen deficiency sensor. CO2 concentrations can reach hazardous levels without reducing oxygen enough to activate a typical low-oxygen alarm. Facilities where carbon dioxide is a potential hazard should use an appropriate CO2 safety monitor.
What is the OSHA exposure limit for carbon dioxide?
OSHA's permissible exposure limit for carbon dioxide is 5,000 ppm as an 8-hour time-weighted average (TWA). Other occupational exposure guidelines may establish additional short-term or immediately dangerous concentration thresholds. Facilities should follow applicable OSHA, NIOSH and local safety requirements.
Where should gas detectors be installed in a cold storage facility?
Gas detector placement depends on the gas being monitored, potential leak sources, ventilation, room configuration and equipment manufacturer's instructions. Potential monitoring locations can include refrigeration machinery rooms, cold rooms, walk-in freezers, packaging lines, cylinder or tank storage areas and other locations where gas could accumulate.
Do cold storage facilities need CO2 monitors?
Facilities that use, store or generate significant quantities of carbon dioxide should evaluate the need for CO2 monitoring as part of their facility-specific risk assessment. CO2 monitoring may be particularly important around refrigeration equipment, dry ice storage, bulk CO2 systems and other areas where a release could cause elevated concentrations.
What is the difference between a CO2 monitor and an oxygen deficiency monitor?
A CO2 monitor directly measures carbon dioxide concentration, while an oxygen deficiency monitor measures the percentage of oxygen in the atmosphere. The correct monitor depends on the gas hazard. Facilities using multiple gases may require more than one type of gas detection.
Why is ammonia gas monitoring important in food refrigeration?
Ammonia is commonly used in industrial refrigeration because of its effective refrigeration properties. However, an ammonia leak can create a serious health and safety hazard. Ammonia detection systems can provide early warning of a release and may be integrated with ventilation, alarms and other facility safety controls.
Should frozen food facilities use fixed or portable gas detectors?
Many facilities use both. Fixed gas detection systems continuously monitor designated areas and can provide facility-wide alarms or control ventilation equipment. Portable gas detectors can provide personal protection, temporary monitoring or atmospheric testing when employees enter areas where gas hazards may be present.
Can gas detectors be connected to ventilation systems?
Yes. Depending on the gas detection system and facility design, fixed gas monitors can use relay outputs to activate exhaust fans, ventilation equipment, warning devices, gas shutoff valves or other safety systems when configured alarm thresholds are reached.
How often should gas safety monitors be calibrated?
Calibration and maintenance intervals depend on the specific sensor, manufacturer requirements, environmental conditions and applicable regulations. Facilities should follow the gas detector manufacturer's recommended calibration, testing and maintenance schedule to ensure the system continues to provide accurate measurements and alarms.
What is the best gas detector for a frozen food storage facility?
There is no single gas detector that is appropriate for every frozen food facility. The correct system depends on the gases being used, refrigeration equipment, room size, ventilation, potential leak locations and applicable safety requirements. A facility-specific gas hazard assessment can help determine whether CO2, oxygen, ammonia or multi-gas monitoring is needed.
