Dust & Powder Flammability
Let HEL Help
- By assessing your process to identify potential hazards for which dust testing may be required.
- By provision of test facilities to produce the required data on dusts and powders.
- By using our experience and expertise to interpret the results from testing and to recommend an appropriate basis of safety.
- By providing an independent assessment of available protection equipment.
We can offer you state of the art test facilities at competitive rates, with a rapid turnaround of results, along with an excellent follow-up service. All of our laboratory procedures for testing the flammability of dusts and powders follow the latest European guidelines.
The A/B classification
A qualitative assessment of the explosibility of a dust at room temperature. It characterises a dust into one of two categories:
- Group A - dusts which ignite and propagate a flame (explosible)
- Group B - dusts which do not propagate a flame
Minimum Ignition Energy (MIE)
This sequence of experiments measures the ease of ignition of a dust cloud by electrical and electrostatic discharges. For this we use the Kuhner Mike 3 apparatus.
Minimum Ignition Temperature (MIT)
This test is used to determine the lowest temperature of a hot surface which will cause a dust cloud to ignite and propagate flame. The value is particularly relevant to problems involving large heated areas of plant, e.g. the surface of a drier.
The 20-Litre sphere apparatus is used to measure the maximum pressure and maximum rate of pressure rise during a dust or powder explosion. The Kst value can then be calculated from the latter: this information is used to correctly specify explosion relief venting or explosion suppression systems.
Other dust flammability measurements including the Limiting Oxygen Concentration (LOC) and the Minimum Explosion Concentration (MEC) are also made in the 20 litre sphere equipment. Some other dust explosion and flammability tests that we offer include:
- Layer Ignition Test (LIT)
- Air over layer
- Diffusion cell (ramped temperature or isothermal)
- UN transportation of dangerous goods basket test (ramped temperature)
- Series of isothermal self-heating basket tests
- Aerated cell (ramped temperature or isothermal)
- Burning number (or BZ classification)
- Flammable gas generation
- Bulk resistivity and charge decay
ATEX, DSEAR, and SI 258 compliance
In the UK the Dangerous Substances and Explosive Atmospheres Regulations (DSEAR) implement two European Directives, Atmosph-res Explosibles (ATEX 137) and parts of the Chemical Agents Directive (CAD), see http://www.hse.gov.uk/fireandexplosion/dsear/background.htm. In Ireland ATEX 137 is implemented as SI 258, see http://www.entemp.ie/publications/sis/2003/si258.pdf.
Our staff can work with you to make sure that you understand the properties of all the flammable substances that you may be handling and to ensure compliance with these regulations. We can prepare your area classifications, help with risk reduction and your risk assessments, aid with appropriate equipment selection and assemble all the information expected in the explosion protection document.
Strategies for prevention and protection
A hazard is the potential for harm. The risk is the probability and severity of the harm that may result from that hazard.
Whenever possible, hazards should be eliminated thus resulting in an inherent safe activity. Usually this impractical so risk reduction is more usual. Risk assessment involves identifying the hazards and their risks, risk reduction and definition of the appropriate basis of safety. The latter may include a variety of preventative measures - in the dust explosion context these could include eliminating fine powders, handling the powder as a wet paste or inerting the atmosphere in which the powder is to be handled. Where the residual risk still remains unacceptable high then protective measures will also be required. These could include hardware items such as explosion relief panels or suppression systems. Our consultants can help with your risk assessments, the definition of your basis of safety and also the most appropriate preventative and protective measures.