KST for gases

Gas Explosion (Pmax and Kg)

The gas explosion severity test is performed to determine the degree of “explosibility’’ of combustible gases characterized by the dust explosibility parameters, maximum explosion pressure, Pmax and explosibility index, Kg, under specified operating conditions. Kg is the rate of pressure increase during a combustible gas explosion event. Pmax provides insight into the maximum achievable pressure generated during a combustible gas explosion event.


The testing principle is similar to dust explosion measurements with the only difference 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 gas is varied across the three series while adjusting the evacuation pressure accordingly. Electrical arc discharge form a spark generator or chemical ignitors of 10J energy is typically used as the ignition source. Pressure transducers are used to measure the maximum explosion pressure, Pmax and the explosibility index Kg.


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


The material is classified as St-1 (Kg between 1-200 bar.m/s), St-2 (Kg between 200-300 bar.m/s) and St-3 (Kg equal to or greater than 300 bar.m/s). St-1 rated gases have weak explosion characteristics while St-2 and St-3 rated gases have strong and very strong explosion characteristics respectively.  The significance or application of the Gas Explosion Severity Test lies in its crucial role in assessing and understanding the potential risks associated with combustible gases. This test provides valuable information about the severity and explosibility of gases, offering critical insights for industries dealing with combustible gases. The results of this test can be used to design deflagration containment, venting and suppression systems. These values are applicable to the design of protective measures, such as deflagration venting per NFPA 68, VDI Method 3673 or ISO Method 6184.


When gases are determined to be explosible (Go), they must be subjected to the explosion severity test to determine the degree to which the gas can explode. Performing the Gas Explosion Severity Test at appropriate intervals, especially during material changes, process modifications, or as mandated by regulations, is crucial to ensure workplace safety and prevent potential dust-related incidents in industries where combustible gas is present.

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.