Limiting Oxygen Concentration LOC Testing

Limiting Oxygen Concentration of Combustible Gas (LOC)

The Limiting Oxygen Concentration (LOC) for combustible gas refers to the minimum oxygen level in the air at which a gas explosion or combustion involving the gas cannot be sustained, even in the presence of an ignition source or sufficient fuel. It represents the lower boundary below which the gas-air mixture is unable to support combustion or explosion. 


The testing principle is similar to the determination of LOC for dust with the only difference being that the dust dispersion step inside the sphere is omitted. The pressure before adding the combustible gas is reduced to less than 0.4 bar to leave space for the gas. For example, for the use of methane concentrations of 5 vol % and 10 vol %, the partial pressures of methane are 0.05 bar and 0.10 bar respectively, and the evacuation pressures are to be 0.35 bar and 0.3 bar respectively. The concentration of the oxygen is reduced from 21% until the amount of oxygen can no more sustain the explosion of the gas.


The Kg/Pmax test is conducted in accordance with the European Standard EN 15967


The LOC of the gas is determined from the pressure ratio generated in the Sphere. When the pressure ratio in the sphere at any gas-air mixture is 2.0 or greater, the gas is deemed to have ignited. The lowest concentration of oxygen below which ignition of the gas is not possible is deemed the limiting oxygen concentration of the gas.

WHEN TO PERFORM (LOC of combustible gas)

Determining the Limiting Oxygen Concentration (LOC) is essential in various scenarios, especially in environments where flammable materials, including combustible gas, are present. When inerting is used as a measure to prevent gas explosions, it is recommended to establish the limiting oxygen concentration to understand the highest oxygen concentration that can be allowed in the process. Performing Limiting Oxygen Concentration (LOC) assessments at appropriate intervals, especially during new material introductions, regulatory compliance checks, and incident reviews, helps in ensuring workplace safety and preventing potential fire or explosion hazards associated with combustible materials.

Why work with Prime Process Safety Center

  • Prime Process Safety Center is a leader in process safety testing with very experienced laboratory personnel. At Prime Process Safety Center our goal is to provide accurate, reliable and defensible data that meets industry and regulatory standards. We understand the need for the quality of your data, and we work assiduously to achieve just that.
  • We are knowledgeable and experienced in performing gas explosion severity testing, ensuring accurate and reliable results. 
  • We have state-of-the-art gas explosion severity testing equipment, providing precise and sensitive measurements. 
  • We follow strict testing protocols and quality control measures to ensure consistent and reliable test results. 
  • Our team can interpret and analyze the data obtained from the tests, providing valuable insights and recommendations for your specific application or research.


What causes combustible gas explosions?

Combustible gas explosions are typically caused by the ignition of a gas-air mixture in the presence of an ignition source. Common factors include leaks, inadequate ventilation, and the presence of an open flame or spark.

How can I prevent combustible gas explosions in my workplace or home?

Answer: Prevention measures include regular gas leak inspections, proper ventilation, using explosion-proof equipment, and following safety guidelines for handling and storing combustible gases. Additionally, educate individuals on proper procedures and emergency response protocols.

What should I do in case of a suspected gas leak?

Answer: If you suspect a gas leak, evacuate the area immediately. Do not use electrical switches or devices, as they can create sparks. Contact emergency services and the gas company. Wait for professionals to assess and address the situation.

Are there specific safety standards for handling combustible gases?

Answer: Yes, there are industry-specific safety standards and regulations that outline guidelines for the handling, storage, and transportation of combustible gases. Compliance with these standards is crucial for minimizing the risk of explosions.

How can I ensure the proper storage of combustible gases?

Answer: Store combustible gases in well-ventilated areas away from ignition sources. Use approved containers and follow guidelines for proper labeling. Implement safety measures such as fire-resistant cabinets and ensure employees are trained on safe storage practices.