Our Solutions: Testing
Combustible Dust Testing & Dust Explosion Analysis
7–10 Day Turnaround | NFPA 652 / NFPA 660 Laboratory Testing
Comprehensive laboratory testing is an important first step in an effective combustible dust safety program. This testing helps determine whether a facility’s dusts or powders can catch fire or cause explosions, which supports hazard identification and risk assessments, equipment design, and compliance with NFPA 652/NFPA 660 standards.
Testing typically starts with initial screening tests to determine if materials create fire or explosion hazards. The Combustibility Screening (Burning Behavior) test identifies if materials can ignite and sustain burning when present as a settled dust layer, indicating a potential fire hazard. The Explosibility Screening (Go / No Go) test gives a clear ‘yes or no’ answer on whether materials can explode when dispersed as a dust cloud, which pose an explosion hazard.
By starting with these screening tests, facilities can confirm if further detailed testing is needed.
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Using our combustible dust testing services, you will:
- Receive fast, reliable results within 7–10 business days to keep your Dust Hazard Analysis and compliance projects on schedule.
- Obtain accurate, test-based data that meets NFPA 652 and NFPA 660 requirements for thorough hazard evaluation and regulatory compliance.
- Make informed risk reduction and protection design decisions based on verified ignition sensitivity and explosion severity data to guide safety measures and reduce combustible dust risk.
- Receive the critical data needed to inform your Dust Hazard Analysis (DHA), enabling proactive identification of combustible dust hazards to help prevent costly incidents and operational downtime.
When explosibility is confirmed, NFPA recommends conducting three important follow-up tests to measure how easily the dust ignites and how severe an explosion could be.
Sigma-HSE’s accredited laboratory performs all combustible dust tests in accordance with ASTM standards and referenced by NFPA 652 / NFPA 660, including:
- Minimum Ignition Energy (MIE): Determines the lowest energy needed to ignite a dust cloud.
- Explosion Severity (Pmax, dP/dtmax, KSt): Measures the maximum rate of pressure rise (KSt) and maximum explosion pressure (Pmax) of a dust cloud explosion.
- Minimum Explosible Concentration (MEC): Identifies the lowest concentration of dust in air that can propagate an explosion.
Additional Material Property Assessments
Beyond referenced tests, our lab offers a complete set of material property assessments to give you a detailed understanding of your dust’s behavior:
- Minimum Ignition Temperature Cloud (MIT Cloud): The lowest temperature at which a dust cloud could ignite.
- Minimum Ignition Temperature Layer (MIT Layer): The lowest temperature for ignition of a dust layer.
- Limiting Oxygen Concentration (LOC): The minimum oxygen level below which an explosion is unlikely.
A comprehensive approach to combustible dust safety combines laboratory testing with on-site risk assessments and compliance consulting.
Please contact us if you have specialized combustible dust testing needs, or if you require a Dust Hazard Analysis (DHA) or other services related to powder and combustible dust explosion safety.
Discover Our Range of Combustible Dust Testing Solutions
Protecting people, workplaces, and equipment from dust-related explosions and fires begins with understanding the hazards.
Sigma-HSE’s combustible dust testing laboratory provides comprehensive testing solutions with a standard turnaround of 7–10 business days from sample receipt. These services help identify and characterize material dust hazards and evaluate the associated fire and explosion risks.
All testing is conducted in accordance with internationally recognized standards, ensuring accurate, consistent, and reliable results for safer operations.
Explosibility Screening (Go / No Go Testing)
Standards & Schedule of Accreditation
ASTM E1226 / BS EN ISO IEC 80079-20-2
Test
This test is conducted to assess whether dust or powder will form a flammable atmosphere or support flame propagation when dispersed as a dust cloud in the air. It’s a purely qualitative test that categorizes a dust or powder into one of two groups:
Explosible – Explosible within a dust cloud
Non-Explosible –Non-explosible within a dust cloud
Varying concentrations of dust are dispersed into a 20L explosion vessel and exposed to at least 5-kJ (10-kJ preferred) ignition source. Piezoelectric transducers then monitor a vessels atmosphere for ignition in the form of pressure rise.
Dust and powders that are found to be explosible will present a flammable atmosphere when dispersed as a cloud. Therefore, if a sufficient ignition source is present then there is a serious risk of hazardous situations arising.
NFPA 652 requires an on-site Dust Hazards Analysis (DHA) within a facility that has explosible and/or combustible materials in process. These combustible dust hazards may result in product loss and, potential operator injury or fatality. Additional testing is required to develop a suitable basis of safety for each process handling an explosible and/or combustible powder.
Explosibility Screening (Go / No Go Testing) Benefits
Dust particles that are found to be non-explosible will not present a flammable atmosphere when dispersed as a cloud. As a result, dust and powders that are found to be non-explosible are not subject to NFPA 652 requirements in regard to a dust cloud explosion hazard of a dust cloud*. However, you will need to confirm that your sample does not propagate a flame while in a pile/layer by testing by using the Burning Behavior/VDI method.
Utilizing the Go/No Go and Combustible Screening test to determine the Burning Behavior by using the VDI 2263/BS EN 17077. These screening methods (Go/No/Go and VDI) can save the need to conduct further dust explosion dispersive testing to establish a suitable basis of safety for combustible dust hazards.
Minimum Ignition Energy (MIE)
Standards & Schedule of Accreditation
ASTM E2019 / BS EN ISO IEC 80079-20-2/BS EN 13821 (withdrawn)
Test
The Minimum Ignition Energy (MIE) test is conducted to determine the lowest spark energy that can ignite a powder when dispersed in the air as a dust cloud. A purely capacitive generated spark is used to assess electrostatic discharges (brush, spark, transitional/propagating brush discharges).
An inductively generated spark is selected for mechanical (friction, impact and grinding) or electrical (wire short, electrical contact) spark incendivity analysis.
Working through a range of dust powder concentrations, potentially combustible dust is dispersed into a 1.2L liter glass vessel using dry compressed air. These momentarily suspended dust particles/clouds are then exposed to sparks of known energy for a selected duration. Following this, energy is then lowered, while dust powder concentration and time delay are varied until the ‘MIE’ is established.
Safety Minute-MIE -Minimum Ignition Energy -Test
Minimum Ignition Energy (MIE) Benefits
Minimum Ignition Energy (MIE) data is typically used to define the minimum spark energy needed to ignite a cloud of combustible process material in the working environment. MIE is one of three core tests where ‘Avoidance of Ignition Sources’ is the ‘basis of safety’ for the operation. This approach tests combustible dust or powders to determine how sensitive they are to ignition sources such as electrostatic discharge, mechanical & electrical sparks and hot surfaces.
The basis of safety is often used when charging vessels from sacks, IBCs or FIBCs, pneumatic conveying, milling and tableting operations. Combustible dust that can create a flammable atmosphere is found to be insensitive to ignition and therefore, it is easy, practical and cost-effective to ensure that an ignition source capable of initiating a dust explosion is not present.
A sub-group of ‘Avoidance of Ignition Sources’ are the electrostatic properties of products and materials used in a process environment. This may include the electrostatic properties of materials being processed, electrostatic properties of containers or Personal Protection Equipment (PPE). This is particularly important where process materials are found to be very sensitive to ignition.
Minimum Ignition Temperature, Cloud ( MIT cloud)
Standards & Schedule of Accreditation
ASTM E1491 / BS EN ISO IEC 80079-20-2” to the standards before BS EN 50281-2-1
Test
The Minimum Ignition Temperature, Cloud (MITcloud) test is conducted to determine the lowest temperature at which a hot surface will ignite combustible dust or powders when dispersed in air.
Working through a range of combustible dust concentrations, powders are dispersed through a heated vertical ‘Godbert-Greenwald’ furnace using compressed air. Once an ignition temperature is observed, the furnace temperature is reduced. Dispersion pressure and combustible dust powder concentration are varied until an ‘MIT’ is established.
Minimum Ignition Temperature, Cloud (MITcloud) Benefits
The MITcloud test is one of three core tests used to access combustible dust ignition sensitivity. It is generally used when the avoidance of ignition sources is the ‘basis of safety’. MIT test data is required for defining the maximum operating temperature for electrical and non-electrical equipment used in areas where test material is present.
This section seems to be talking about MIE benefits. We need to change this to something along the lines of the following:)
Avoidance of ignition source as the ‘basis of safety’ within heated atmospheres like ovens or heavy machinery. The MIT of Dust Cloud will provide the minimum temperature where the dust will react within a dust cloud. Your team can establish a temperature below the MIT level that is a safe area to operate. You can have alerts set up to shut down the operation should the temperature exceed the established temperature BELOW the MIT result.
Minimum Ignition Temperature, Layer (mIT Layer)
Standards & Schedule of Accreditation
ASTM E2021 / BS EN ISO IEC 80079-20-2 to the standards before BS EN 50281-2-1
Test
The Minimum Ignition Temperature, Layer (MITlayer) test is conducted to determine the lowest temperature at which a hot surface will ignite combustible dust or powders when settled as a dust layer.
Potentially combustible dust is placed onto an isothermally heated hotplate and formed into a 12 mm layer. Once an ignition temperature is observed, the hotplate temperature is reduced and tested. This is then repeated with fresh combustible dust until the lowest ignition temperature is established.
Minimum Ignition Temperature, Layer (MITlayer) Benefits
The MITlayer test is one of the three core tests for accessing a material’s ignition sensitivity. It is generally used when the avoidance of ignition sources’ is the ‘basis of safety’ for an operation. This data is required for defining the maximum operating temperature for electrical and non-electrical equipment used in areas where test materials are present.
The avoidance of sources of ignition as the ‘basis of safety’, is often used for processes such as charging vessels from sacks, IBCs or FIBCs, pneumatic conveying, milling and tableting operations. Many materials that can create a flammable atmosphere are found to be insensitive to ignition and therefore, it is easy, practical and cost-effective to ensure that an ignition source capable of initiating a dust explosion is not present.
Explosion Severity (Pmax, dP/dtmax, KSt)
Standards & Schedule of Accreditation
ASTM E1226 / BS EN 14034 parts 1 & 2
Test
The explosion severity test is conducted to determine the maximum explosion pressure (Pmax), maximum rate of pressure rise (dP/dt)max and the dust constant Kst value of an ignited combustible dust, dispersed in the air, as a dust cloud.
Working through a range of potentially combustible dust concentrations, powders are dispersed into a 20L explosion vessel (sphere) using dry compressed air. These suspended dust clouds are then exposed to a large 10 kJ chemical source of ignition and the following dust explosion is monitored, measured, and recorded, using high-accuracy piezoelectric transducers. Testing is conducted over a wide range of combustible dust powder concentrations that enable flammability curves of Pm, dP/dt & Kst to be generated, along peak values. Data created via the 20-Liter demonstrates what the maximum dust explosion pressure would be under optimum concentration.
Explosion Severity (Pmax, dP/dtmax, KSt) Benefits
Data generated by the explosion severity test is predominantly used for either the design of dust explosion protection systems (venting, containment or suppression) or to confirm if a material is appropriate for processes within an established hazard protection system. This data will also be used to ensure the dust collector is properly sized and vented to accommodate your material within process.
Minimum Explosion Concentration (MEC)
Standards & Schedule of Accreditation
ASTM E1515 / BS EN 14034 part 3
Test
The Minimum Explosive Concentration (MEC) or Lower Explosive Limit (LEL) test is conducted to determine the minimum quantity of combustible dust dispersed in the air, as a cloud that will form a flammable atmosphere.
Working through a range of decreasing combustible dust powder concentrations, a powder is dispersed into a 20L explosion vessel (sphere) using dry compressed air. The suspended potentially combustible dust cloud is then exposed to a large 2.5 kJ chemical ignition source and the following dust explosion is monitored, measured, and recorded, using high-accuracy piezoelectric transducers. Once ignition is achieved, the concentration of the combustible dust powder is then reduced until ignition is not possible and the ‘MEC’ is established.
Minimum Explosion Concentration Benefits
Data generated by the minimum explosive concentration test is predominantly used to ensure that levels of airborne dust are kept below the minimum threshold by which a flammable atmosphere can be created and a combustible dust explosion could occur. It may also confirm if a material is appropriate for processes with an established LEV or set dust extraction rate.
Limited Oxygen Concentration (LOC)
Standards & Schedule of Accreditation
ASTM E2931 / BS EN 14034 part 4
Test
The Limiting Oxygen Concentration (LOC) test is conducted to determine the minimum quantity of oxygen, within an atmosphere, that will enable combustible dust dispersed in the air to ignite when in contact with an ignition source.
Working through a range of combustible dust concentrations, a powder is dispersed into a 20L explosion vessel (sphere) using dry compressed air and nitrogen. Using partial pressures, oxygen content within the sphere at the time of ignition is controlled. These suspended dust clouds are then exposed to a large 2.5 kJ chemical ignition sources and the following dust explosions are monitored, measured, and recorded, using high-accuracy piezoelectric transducers. Once ignition is achieved at a specific oxygen concentration, oxygen concentration is then reduced, and powder concentration is varied, until ignition is not possible, and the ‘LOC’ is established.
Limited Oxygen Concentration Benefits
Data generated by the Limited Oxygen Concentration test is predominantly used for either the design of nitrogen inerting systems or to confirm if combustible dust or powders are appropriate for processes with an established limited oxygen atmosphere. As many systems are set at a much lower oxygen level than required, this can result in large nitrogen costs. This can be avoided or reduced, by knowing a combustible dust’s specific LOC and setting oxygen levels accordingly.
Combustibility Screening (Burning Behavior)
Standards
VDI 2263 and BS EN 17077
Test
This combustible dusts test is conducted to assess the behavior (severity) of combustion propagation through a material deposit when ignited by an external ignition source.
A small powder strip is formed onto a heat-resistant, non-porous plate and ignition trials are performed using a hot (1000 °C) platinum wire. The burning behavior is numerically rated from 1 (material does not ignite) to 6 (supports rapid combustion) in accordance with the test standards characterization table. The rating is known as “CC” or Combustibility Class and testing is performed at ambient and elevated environmental temperature conditions.
| Type of Reaction | CC | Reference Product | |
| No spreading of fire | No ignition | 1 | Table Salt |
| Brief ignition and rapid extinction | 2 | Tartaric Acid | |
| Localized combustion or glowing with practically no spreading | 3 | Lactose | |
| Fire spreads | Glowing without sparks, (smoldering ) or slow decomposition without flame | 4 | Tobacco |
| Burning with flame or spark generation | 5 | Sulphur | |
| Very rapid combustion with flame propagation or rapid decomposition without flame | 6 | Black Powder | |
Burning Behavior Benefits
When the burning rate of solid material is known, fires or explosion dust hazards caused because of the introduction of hot embers or friction heat (on bearing failure) can be predicted and then avoided or mitigated. It also can be used as a screening tool to highlight materials that should be classified as a ‘flammable solid’ for transportation.
Why Combustible Dust Testing is Essential
Combustible Dust Testing is essential for industries that handle fine particulate materials. With thorough Combustible Dust Testing, you can:
- Identify dust hazards that could lead to explosions, fires, or other serious incidents.
- Assess the explosibility of dust particles, including their size, concentration, and ignition sensitivity.
- Develop effective strategies to mitigate dust-related risks and enhance workplace safety.
- Ensure adherence to safety regulations and industry standards, such as OSHA and NFPA, to mitigate risks of penalties, operational disruptions, or reputational damage.
By incorporating Combustible Dust Testing into your safety protocols, you can better manage risks, safeguard your workforce, and maintain operational integrity.
Combustible Dust Testing FAQs
What is combustible dust?
Combustible dust consists of finely divided solid particles that are prone to ignition and explosion when suspended in air at certain concentrations. These dust particles originate from materials like wood, grains, sugar, powdered milk, flour, and many industrial chemicals. Combustible dust poses significant fire and explosion hazards in workplaces where dust accumulates and becomes airborne. (Reference: OSHA Hazard Communication Guidance for Combustible Dust)
What’s the difference between combustible and explosible dust?
All explosible dusts are combustible, but not all combustible dusts are explosible. Understanding which type of dust is present is vital because explosible dust presents a higher and more serious risk of fire and explosion.
- Combustible dust can ignite and burn when accumulated in a pile or layer.
- Explosible dust can ignite and explode when dispersed in air as a cloud.
Why do I need my dust tested?
What is ignition sensitivity and explosion severity?
Ignition sensitivity refers to how easily dust particles can ignite when exposed to an ignition source, such as a spark or flame. This property helps assess the minimum energy required to ignite the dust cloud or dust layer, indicating how prone the dust is to start a fire or explosion.
Tests for ignition sensitivity include:
- ASTM E2019: Minimum Ignition Energy (MIE) test, which measures the lowest electrical energy that can ignite a dispersed dust cloud.
- ASTM E1515: Minimum Ignition Temperature of a Dust Cloud, determining the lowest temperature at which a dust cloud ignites.
- ASTM E2021: Minimum Ignition Temperature of a Dust Layer, assessing the ignition temperature of a settled dust layer.Explosion severity describes the potential intensity or destructive power of a dust explosion once ignited. It quantifies parameters like maximum explosion pressure and the rate of pressure rise, which are critical for designing explosion protection systems such as venting or suppression.
Relevant tests for explosion severity include:
- ASTM E1226: Standard Test Method for Explosibility of Dust Clouds, which measures peak explosion pressure (Pmax) and maximum rate of pressure rise ((dP/dt) max).
- ASTM E1515: Minimum Explosible Concentration helps assess explosion characteristics through ignition temperature data.
Together, ignition sensitivity tests determine the likelihood of ignition, while explosion severity tests measure the potential impact of an explosion. This detailed dust testing enables facilities to evaluate risks accurately and implement appropriate fire and explosion prevention and mitigation strategies.
Do I collect my own dust sample or does someone come onsite to collect it for me?
While a consultant can come onsite to collect dust samples, this service often adds significant expense for a task that is typically straightforward and easy to do yourself.
To collect a dust sample for testing, you simply need a clean container, often a glass jar with a secure lid, and a way to gather dust from areas where it naturally accumulates in your facility, like dust collectors or ventilation housings. It’s important to use clean tools and avoid contamination. The amount you collect can vary depending on the testing requirements, but initial screening usually requires a small sample, while more comprehensive testing needs a larger amount. If your facility handles mixed dusts, try to collect samples that represent the main dust types.
Once collected, samples should be packaged securely and clearly labeled before shipping to the testing laboratory. More detailed guidance on sample amounts, collection techniques, packaging, and shipping is provided with your Sigma-HSE quote to ensure you have all the information necessary for a successful and accurate dust test.
By collecting your own samples following these simple guidelines, you can save on costs and ensure your samples represent your facility’s actual dust hazards. If you prefer or require assistance, consultants are available to collect samples onsite as part of a Dust Hazard Analysis or other services.
What do NFPA 652 and NFPA 660 say about testing dust/powder materials used in facilities?
NFPA 652 and NFPA 660 set clear requirements for testing dusts and powders handled or processed in facilities to identify potential combustible dust hazards. This involves testing to identify both combustibility (a fire risk) and explosibility (a deflagration and explosion risk). These initial tests typically include screening the dust to see if it can ignite or explode.
Once confirmed that materials pose combustible dust hazards, NFPA 652 requires facilities to conduct a Dust Hazard Analysis (DHA), which involves laboratory testing of dust samples to assess ignition sensitivity and explosion characteristics (MIE, Kst/Pmax). This testing helps identify fire and explosion risks to safeguard people and property, and design proper equipment safety controls.
NFPA 660 builds on this by specifying required dust property tests such as Kst (deflagration index)/Pmax (maximum explosion pressure), Minimum Explosive Concentration (MEC), Minimum Ignition Energy (MIE), and Minimum Ignition Temperature (MIT). These tests are essential for classifying dust hazards, maintaining compliance, and implementing effective explosion prevention and mitigation measures.
What’s the difference between Combustible Dust Testing and Dust Hazard Analysis (DHA)?
Combustible dust testing and Dust Hazard Analysis (DHA) are related, but distinct, components in managing dust explosion risks, especially under NFPA standards like NFPA 652 and NFPA 660.
Combustible dust testing is a specialized laboratory process that evaluates whether powders or dusts handled or generated in a facility pose fire and explosion hazards. Tests measure key dust characteristics to understand how a material behaves under specified conditions. This testing provides scientific data about the material’s combustion and explosibility potential, sensitivity to ignition sources, and quantifies the severity of its explosion properties.
Dust Hazard Analysis (DHA) is a broader, systematic evaluation of dust hazards within the facility environment. Mandated by NFPA 652/660, a DHA examines how dust behaves in actual processing and handling operations, identifying ignition sources, dust accumulation areas, and other risk factors. The ultimate goal is to develop effective dust hazard controls and safety measures to protect workers and equipment.
Importantly, dust testing supplies essential data that feeds directly into the DHA. Accurate and current test results on a facility’s specific dust material ensure that DHA findings and recommendations reflect the true hazards present. Testing can be completed before or during the DHA to support hazard evaluation and risk management.
Combustible dust testing is often the first step that produces critical material data, while the DHA is a comprehensive facility-level analysis that uses this data alongside operational factors to identify and control combustible dust hazards.
Can't find the combustible dust testing you need?
Get in touch with one of our experts to learn how our combustible dust testing services can help you prevent dust explosions, fires, and other related hazards.
From fine wood dust particles to airborne dust, and from testing a material’s ignition sensitivity and severity to evaluating primary and secondary dust explosions, we provide combustible dust testing solutions for any material, product, or chemical that may pose a fire or explosion hazard.
COMBUSTIBLE DUST & POWDER FLAMMABILITY TESTING
Test your dusts & powders and prevent combustible dust explosions
Protecting your people, workplaces, business, and the environment from explosion hazards, fires, or other combustible dust risks relies on the awareness and maintenance of potentially combustible dust and powder materials through proper combustible dust testing.
Sigma-HSE’s combustible dust testing labs offer comprehensive standard and custom combustible dust testing packages to aid you in the identification and characterization of these hazardous materials and their related risks to a dust explosion.
The Sigma-HSE Advantage
Request a Quote for Combustible Dust Testing
How to get your combustible dust & powders tested
Contact Us
Get in touch with one of our experts so we can learn more about your specific process and combustible dust testing requirements. We'll then generate and send you a customized quote.
Prepare & Ship
Prepare your combustible dust samples and ship them to one of our global laboratories.
Dust Testing, Analysis & Reports
Once we've received your potentially combustible dust or powder samples, we'll begin testing and analyzing. We'll then create and send you a custom in-depth report detailing the potentially hazardous properties of your materials.
Post-Project Support
If you need support after receiving your report, our after-project support team will be on hand to assist you with any questions you may have about your combustible dust or powders. We can also aid you in your understanding of what combustible dust explosion hazard prevention measures will be most suitable for your processes.
Test your explosive dust and powders with combustible dust testing to understand your dust hazards.
Getting your combustible dust testing for dusts and powders is an important step to prevent a dust explosion hazard. Learn more about how we can assist you to prevent a dust explosion, fire and other related hazards.