Combustible Dust Testing and Analysis
Accurate laboratory testing to identify combustible dust hazards, evaluate ignition sensitivity, and determine explosion characteristics.
Stonehouse Process Safety provides specialized combustible dust testing to help manufacturers understand the fire and explosion hazards associated with the powders and particulate materials they handle.
Our ISO/IEC 17025:2017-accredited laboratory offers a comprehensive range of testing services, including explosibility screening, minimum ignition energy (MIE), ignition temperature, explosion severity (Kst), minimum explosible concentration (MEC), and limiting oxygen concentration (LOC) testing.
Our process safety specialists can also help interpret test results and apply the findings to your facility’s Dust Hazards Analysis (DHA) and explosion prevention and protection strategies.
What is Combustible Dust Testing?
Combustible dust testing generally refers to the laboratory evaluation of finely divided combustible particulate solids that may present a fire, flash-fire, or explosion hazard when dispersed in air or another oxidizing atmosphere.
These tests are typically performed in specialized laboratories and include preliminary screening to determine a material’s combustibility and explosibility, as well as more detailed testing to characterize its ignition sensitivity and explosion severity. The resulting data helps facilities better understand the hazards associated with their materials and make informed decisions regarding appropriate fire and explosion prevention and protection measures.
Why is Combustible Dust Testing important?
Combustible dust testing provides critical data to help facilities understand and evaluate the fire and explosion hazards associated with their materials. Testing can determine:
- Whether a material is explosible.
- How easily a dust cloud can ignite.
- The temperatures at which dust clouds and layers can ignite.
- The potential severity of a dust explosion.
- The minimum concentration needed to produce an explosion.
- The oxygen concentration below which combustion cannot be sustained.
Relying solely on Safety Data Sheets (SDSs) or other publicly available information can sometimes result in an overly conservative assessment of a material’s explosibility characteristics. Laboratory testing of a representative sample provides data specific to the material being handled, offering a more accurate understanding of its actual fire and explosion hazards.
This material-specific data can significantly enhance Dust Hazards Analyses (DHAs) and other combustible dust assessments, helping facilities make more informed decisions and develop practical, appropriately tailored explosion prevention and protection strategies.
Why Choose Stonehouse for Combustible Dust Testing?
At Stonehouse Process Safety, we combine specialized laboratory testing with decades of expertise in combustible dust hazards, explosion prevention, and process safety. Our ISO/IEC 17025:2017-accredited laboratory provides reliable, material-specific data to help manufacturers understand the fire and explosion risks associated with their operations.
Unlike laboratories that focus solely on generating test results, Stonehouse brings together experienced laboratory scientists and process safety consultants who understand how those results apply to real-world industrial processes. From identifying the appropriate testing program to interpreting results for Dust Hazards Analyses (DHAs), hazardous area classifications, and explosion protection systems, our team provides practical guidance at every stage.
We work with clients across a wide range of industries, providing responsive turnaround times, customized testing programs, and direct access to technical specialists. Our goal is not simply to provide test data, but to help you understand what it means for the safety of your facility.
Combustible Dust Testing for a Wide Range of Industries
Combustible dust hazards can arise across many manufacturing and industrial processes, including material handling, mixing, milling, drying, conveying, and dust collection.
Stonehouse provides combustible dust testing services for materials used in industries including:
- Food and Agriculture: Flour, sugar, starches, grain, proteins, spices, and other food powders.
- Pharmaceuticals and Chemicals: Active pharmaceutical ingredients, excipients, specialty chemicals, and fine powders.
- Metals and Additive Manufacturing: Aluminum, magnesium, and other metal powders used in manufacturing and powder processing.
- Wood, Paper, and Building Materials: Wood dust, paper fibers, and dust generated during cutting, sanding, and processing.
- Plastics and Polymers: Plastic resins, polymer powders, and other combustible particulate materials.
Because combustibility and explosibility characteristics can vary significantly between materials, laboratory testing provides valuable data for evaluating hazards specific to your operations.
Which combustible dust test do I need?
| Testing Objective | Common Laboratory Tests |
|---|---|
| Determine whether a dust is explosible | Go/No-Go |
| Evaluate dust explosion severity | Kst and Pmax |
| Assess electrostatic ignition sensitivity | MIE |
| Evaluate hot-surface ignition hazards | MIT Cloud and MIT Layer |
| Determine the minimum explosible dust concentration | MEC |
| Evaluate oxygen-reduction or inerting systems | LOC |
| Assess burning behavior of solid materials | Burn Rate / Fire Train |
| Characterize particle size distribution | Particle Sieve Analysis |
Go/No Go Explosibility Screening Test
The first step in assessing flash-fire and explosion hazards associated with combustible dust is an explosibility screening – commonly referred to as a Go/No-Go. A representative sample of your dust is dispersed into a cloud and exposed to a strong ignition source inside a closed test vessel. The screening answers a single, decisive question: is the dust cloud capable of igniting and propagating a flame?
For some common materials, this information may be available from Safety Data Sheets (SDSs), manufacturers’ technical bulletins, or other publicly available sources. Otherwise, a Go/No-Go screening test using a representative sample from the process will be required.
If characterized as a Go (Explosible), the dust ignited and sustained a deflagration. The material is capable of supporting a dust explosion, and a full characterization is required.
If your material is a No-Go (Non-Explosible), the dust did not ignite or propogate under test conditions. No further explosion characterization is typically required, though Stonehouse recommends a burn rate screening, and other hazards (self-heating, flammability, etc.) may still warrant review.
Go/No-Go explosibility testing is conducted in accordance with the requirements of the current edition of ASTM International Standard E1226.
Burn Rate/Fire Train Test
The Burn Rate/Fire Train test examines how a material behaves when exposed to fire.
The test is conducted in two parts. Part 1 is a screening test in which an unbroken, 250 mm-long powder train is ignited at one end with a gas burner and observed. The observer notes any combustion along the powder train and measures the flame propagation time over 200 mm.
In Part 2, the procedure is repeated, but with a wetted zone of material created along the powder train.
This test is useful for differentiating between substances that can be ignited and those that burn rapidly or exhibit particularly hazardous burning behavior. As such, it is used in process safety to provide an indication of a material’s combustibility and associated fire risk.
The test also has applications in UN/DOT Classification of Dangerous Goods, where it is used to classify materials as readily combustible solids of Division 4.1 and to determine their subsequent Packaging Group (Groups II and III).
Minimum Ignition Energy (MIE) – Dust Cloud Test
Minimum ignition energy (MIE) measures the minimum energy required to ignite a suspended dust cloud. This data helps assess the likelihood of ignition from common sources such as static electricity, electrical equipment, or mechanical sparks.
Testing is conducted using a modified Hartmann-tube apparatus made of glass or Plexiglas, with a volume of 1.2 liters, which serves as the explosion chamber. The dust sample is dispersed within the Hartmann tube using a pulse of compressed air, and attempts are made to ignite the resulting dust cloud with an electric spark of known energy. Trials are conducted at different dust cloud concentrations and spark energy levels to establish the MIE value.
MIE test results are particularly valuable when evaluating electrostatic hazards and appropriate grounding and bonding practices.
The Minimum Ignition Energy test is performed in accordance with the requirements of the current edition of ASTM International Standard E2019.
Minimum Ignition Temperature – Dust Cloud (MIT Cloud) Test
The Minimum Ignition Temperature – Dust Cloud (MIT Cloud) test determines the lowest temperature at which a suspended dust cloud can ignite.
During the test, a dust sample is dispersed by a pulse of air into a vertically oriented, electrically heated cylindrical oven. Testing is conducted at different temperatures until the minimum temperature required for ignition is established. Ignition is considered to have occurred when the dispersed dust ignites or decomposes, producing flames or an explosion.
Data obtained from the MIT Cloud test can be used to establish safe operating temperatures for equipment such as dryers, ovens, heaters, and other process equipment that may generate elevated temperatures.
The Minimum Ignition Temperature – Dust Cloud (MIT Cloud) test is performed in accordance with the requirements of the current edition of ASTM International Standard E1491.
Minimum Ignition Temperature – Dust Layer (MIT Layer) Test
The Minimum Ignition Temperature – Dust Layer (MIT Layer) test is used to determine the hot-surface ignition temperature at which a dust layer of a specified thickness will begin to self-heat, ignite, or decompose.
Because the ignition temperature depends on the thickness of the dust layer, test data obtained at one thickness may not be applicable to all industrial situations. However, data obtained using a standardized test method provides a relative measure of the hot-surface ignition temperature of a dust layer.
The test is performed by repeatedly placing a dust layer of a specified thickness on a heated hot plate set to different temperatures and observing the results.
The test data can be valuable in determining safe operating conditions in industrial plants, manufacturing processes, and areas where powders are used, stored, or allowed to accumulate. Results from the MIT Layer and MIT Cloud tests are used together to establish maximum operating temperatures for electrical and mechanical equipment used in dusty environments (Class II).
The Minimum Ignition Temperature – Dust Layer test is performed in accordance with the requirements of the current edition of ASTM International Standard E2021.
Explosion Severity (Kst) Test
Explosion Severity testing determines the potential severity of a dust explosion by measuring:
- Maximum Explosion Pressure (Pmax)
- Maximum Rate of Pressure Rise (dP/dt) max
- Explosion Index (Kst)
The severity of an explosion resulting from the ignition of a flammable atmosphere in a confined space is characterized by the maximum rate of pressure rise, resulting from the expanding fireball, and the maximum explosion pressure developed.
During testing, dust samples of varying quantities are dispersed within a 20-liter spherical enclosure and ignited using chemical igniters with a total energy of 10,000 joules (10 kJ). The rate of pressure rise and the maximum pressure generated by the resulting deflagration are measured. The data obtained are then used to calculate the explosion severity index (Kst) for the powder or dust material.
Explosion Severity test results are critical for designing and evaluating explosion protection systems, including explosion venting, suppression, and isolation. These values are also commonly used in Dust Hazards Analyses (DHAs) and other process safety evaluations.
The Explosion Severity test is performed in accordance with the requirements of the current edition of ASTM International Standard E1226.
Minimum Explosible Concentration (MEC) Test
The Minimum Explosible Concentration (MEC) test identifies the lowest airborne dust concentration capable of supporting an explosible.
During testing, successively smaller quantities of dust are dispersed in a 20-liter spherical vessel. At each concentration, an attempt is made to ignite the dust cloud using an energetic chemical igniter. The lowest dust concentration at which a deflagration occurs is defined as the MEC.
Because MEC values may vary depending on the uniformity of dust dispersion, the energy of the igniter, and the criteria used to determine flame propagation, MEC should be considered a relative rather than an absolute measurement.
The test results are useful for evaluating dust collection systems, ventilation, housekeeping practices, and process conditions where airborne dust may accumulate.
The MEC test is performed in accordance with the requirements of the current edition of ASTM International Standard E1515.
Limiting Oxygen Concentration (LOC) Test
Limiting Oxygen Concentration (LOC) is defined as the minimum oxygen concentration below which combustion cannot be sustained, regardless of the fuel concentration. The LOC is dependent on the type of inert (non-flammable) gas used.
During testing, dust samples of varying quantities are dispersed within a 20-liter spherical vessel, and attempts are made to ignite the resulting dust clouds using an energetic ignition source. The tests are repeated at progressively lower oxygen concentrations by replacing a portion of the oxygen-containing atmosphere with an inert gas until the LOC is determined.
The data obtained provide a relative measure of the deflagration characteristics of dust clouds. A dust cloud atmosphere with an oxygen concentration below the LOC is not capable of supporting a deflagration.
The Limiting Oxygen Concentration (LOC) test is performed in accordance with the requirements of the current edition of ASTM International Standard E2931.
Particle Sieve Analysis
Particle sieve analysis is conducted using a series of sieves with specific mesh sizes to determine the percentage of material passing through or retained on each sieve.
Particle size analysis is conducted in general accordance with the requirements of the current edition of ASTM International Standard D1921.
Not Sure Which Combustible Dust Tests You Need?
Selecting the appropriate laboratory tests depends on the characteristics of your material, your processing conditions, and the potential hazards associated with your operation.
Our process safety specialists can help identify the testing necessary to characterize your material’s fire and explosion hazards. We can also interpret the results and help determine how the data should be applied to your Dust Hazards Analysis (DHA) and explosion protection strategy in our free 1-hour follow up meeting (included with every testing project).
What is the combustible dust testing process?
Getting started with combustible dust testing at Stonehouse Process Safety is straightforward. Our laboratory team will work with you to determine the appropriate tests, sample requirements, and turnaround times for your project.
Discuss Your Testing Requirements: Contact our team with information about your material, industrial process, and testing objectives. If you're unsure which tests are necessary, our specialists can help identify an appropriate testing program.
Receive a Customized Proposal: We'll provide a proposal outlining the recommended tests, pricing, sample requirements, and anticipated turnaround time.
Sample Receipt & Testing: Once your samples arrive at our laboratory, our team will log and review the materials before initiating testing in accordance with the agreed-upon scope and applicable test methods.
Receive Your Results: Once testing is complete, you'll receive a technical report documenting the test methods, results, and relevant findings. Our specialists are available to discuss the results and their implications for your facility.
Ready to get started? Contact Stonehouse Process Safety to request a quote or speak with one of our laboratory specialists.
Get in touch
To learn more about our expertise and services in dust explosion prevention & mitigation, call us at +1 609 455 0001 or email us at [email protected] today.
We also offer tailored virtual and in-company process safety training programs on Dust Explosions, Static Electricity and HAC (Hazardous Area Classification) and more. Find further information here.
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