The Science of Combustible Dust Testing
Each dust compound has unique physical and chemical characteristics. A good understanding of both is essential to understand the hazards, and ultimately the risks, associated with the dust being handled.
Identifying Dust Hazards
A typical first step to assessing a hazard level is to review information in the literature. In the case of combustible dust hazards, dust characteristics directly affecting combustibility hazards are a function of process-specific conditions such as concentration, size and shape, moisture content, and dispersion method and duration. Proper characterization of dusts must then be based on testing data of an actual sample from the process.
Chemical characteristics include items such as flammability and explosibility, as well as thermal degradation, instability, sensitivity to ignition and chemical reactivity. Depending on the type of process unit being analyzed and the potential explosion prevention measures to be employed, a testing plan is selected.
ioMosaic has extensive experience with the evaluation and interpretation of dust hazard test data. We can assist with the development of a cost-effective test plan to characterize dust hazards. Let us help you sift through the complicated list of tests to determine which are appropriate for your operations. After the test is conducted, our experts will evaluate and interpret the data and provide a report of the results. Together with our lab partners, ioKinetic, LLC, we can offer a single package that includes test plan development, testing and data analysis, and interpretation. Our experts will work with you to determine the level of analysis that is required for your particular needs.
- Explosion Severity Test
(KSt, Pmax, (dP/dt)max)
- Minimum Ignition Energy (MIE)
- Minimum Auto-Ignition
Temperature (MAIT) of Dust Cloud in Air
- Minimum Explosible Concentration (MEC) of Dust in Air
- Limiting Oxygen Concentration (LOC) Test
- Hot-Surface Ignition Temperature (HSIT) of Dust Layer
- Volume Resistivity and Measured Charge Relaxation Time
- Electrostatic Charging (Chargeability) Test
- Chemical Reactivity/Calorimetry Testing
Explosion Severity Test (KSt)
The testing will be performed per ASTM E 1226-00ε1, “Standard Test Method for Pressure and Rate of
Pressure Rise for Combustible Dust.” The parameters measured are the maximum pressure output and the
maximum rate of pressure rise. These values are applicable to the design of protective measures, such as
deflagration venting per NFPA 68, VDI Method 3673 or ISO Method 6184. The test will be conducted using a
spherical 20-L Siwek chamber. Greater than 750g of sample less than 75μm required.
Minimum Ignition Energy (MIE)
The testing will be performed per ASTM E 2019, “Standard Test Method for Minimum Ignition Energy of a
Dust Cloud in Air” (this standard is very similar to British Standard 5958, 1991 and European Standard: IEC
1241-2-3, 1994). The test will be conducted in a modified 1.2-liter Hartmann chamber. The powder/dust
samples of varying quantities are dispersed in the 1.2-liter vertical tube and attempts are made to ignite the
resultant dust cloud with discrete capacitive sparks of a known energy. Greater than 100g of sample less
than 75μm required.
Minimum Auto-Ignition Temperature (MAIT) of Dust Cloud in Air
Testing will be performed per ASTM E 1491, “Standard Test Method for Minimum Autoignition Temperature
of Dust Clouds.” The test method provides a procedure for performing laboratory tests to determine the minimum
auto ignition temperature (MAIT) of a dust cloud. The test will be conducted in a BAM furnace. Greater
than 80g of sample less than 75μm required.
Minimum Explosible Concentration (MEC) of Dust in Air
Testing will be performed per ASTM E 1515, “Standard Test Method for Minimum Explosible Concentration
of Combustible Dusts.” The test method provides procedure for performing laboratory tests to measure the
minimum concentration of a combustible dust (dispersed in air) that is capable of propagating a deflagration.
The test will be conducted in a 20L chamber or larger. Greater than 80g of sample less than 75μm required.
Limiting Oxygen Concentration (LOC) Test
Testing will be performed per ASTM proposed standard. The tests will determine how much inert (nitrogen
atmosphere) is needed to prevent an explosion from occurring when the dust concentration is in the explosive
range. The cost listed below reflects conducting KSt tests on the exact same material in the same test
campaign. Greater than 200g of sample less than 75μm required.
Hot Surface Ignition Temperature of Dust Layer
An additional cost per sample will be incurred if no DSC is available.
Testing will be performed per ASTME 2021, “Standard Test Method for Hot-Surface Ignition Temperature of
Dust Layers.” Test will determine the hotsurface ignition temperature needed to ignite the material in the dust
layer form. Greater than 500g of sample less than 75μm required.
Volume Resistivity and Measured Charge Relaxation Time
Testing will be performed per ASTM D257-99, “Standard Test Method for DC Resistance or Conductance
of Insulating Materials” (Modified). Additionally, actual charge relaxation time to 37% and 10% of the initial
charge level will be directly measured. Approximately 100mL of sample is required.
Electrostatic Charging (Chargeability) Test
Testing will evaluate the tendency of the material to generate an electrostatic charge and to hold that charge. Additional costs as needed:
Chemical Waste Disposal per sample
Grinding/Sieving to <75 μm as requested per sample
If chemical reactivity is required, please call for a quote. Testing will evaluate the chemical reactivity of pure
components or mixtures of chemicals:
Other Large-Scale Testing
- Large-Scale Testing
- Blasting Cap Test