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Dust Classification
Material Testing

The very first stage of designing the most effective solution for protecting your process is identifying the characteristics of your material. Certain types of product require different methods of protection due to their properties. Moreover, the Dangerous Substances and Explosive Atmospheres Regulations (DSEAR, 2002) require that hazardous substances are fully understood so as to complete risk assessments for the material handling processes. Euratex offer a full range of dust explosion testing to classify these parameters.

Testing laboratory

All of our dust explosion testing is conducted at our accredited partner laboratory who is certified according to EN ISO/IEC 17025:2018. The main tests include:

Minimum Ignition Temperature (MIT)

For dusts, it is important to know the minimum ignition temperature of both a dust-cloud formation and also of a dust layer formation. The minimum ignition temperature values are required to assess the likelihood of ignition during normal operation. The minimum ignition temperature is tested for according to EN ISO/IEC 80079-20-2.

Lower Explosion Limit (LEL)

The lower explosion limit, sometimes referred to as the minimum explosible concentration (MEC), is the smallest concentration of dust that will support combustion of the dust cloud. Lower explosion limit is commonly used to determine whether dust can be controlled to below the limit, preventing an explosion atmosphere from forming (explosion prevention). The lower explosion limit is tested for according to EN 14034-3.

Kst value

The Kst value is the explosibility rate constant of a combustible dust. The Kst value is a key indication as to the severity of an explosion and is one of the core values used to validate suitable explosion protection measures such as explosion venting, explosion isolation and explosion suppression systems. The Kst value is tested for according to EN 14034-2.

Understanding the Kst value of your dust will also allow you to classify the dust. The “ST class” depends on the Kst value as follows:

ST class 1 – Kst value below 200 bar.m/s

ST class 2 – Kst value between 200 – 300 bar.m/s

ST class 3 – Kst value more than 300 bar.m/s

Pmax value

When designing explosion protection, another essential parameter is the Pmax value. The Pmax value is the maximum explosion pressure of the dust. I.e. in the event of an explosion, what is the potential that the explosion pressures can rise to if left unprotected.  The Pmax value is tested for according to EN 14034-1.

Limiting Oxygen Concentration (LOC)

For dusts, the limiting oxygen concentration is the highest level of oxygen at which the dust cannot support combustion. The limiting oxygen concentration is used to develop risk assessments and to assess prevention and protection methods such as inerting a process. The limiting oxygen concentration is tested for according to EN 14034-4.

Minimum Ignition Energy (MIE)

When assessing the risks associated with a combustible dust, it’s essential to compare the minimum ignition energy of the dust with the potential ignition sources in the surrounding areas. The minimum ignition energy is required to gauge the dusts’ sensitivity to ignition. The minimum ignition energy is tested for according to EN 13821.

Other testing includes:

  • Assessing the susceptibility to self-ignition (such as bulk dusts in heated environments)
  • Determining the resistivity of the dust (EN ISO IEC 80079-20-2)
  • Understanding the burning behaviour of dust layers (EN 17077)

As standard, all of our testing includes a sample preparation phase consisting of:

  • Grinding & sieving,
  • Medium size grain analysis (EN 933-1)
  • Determining humidity (water content), ash content & volatile inflammable matter (ISO 562, ČSN 441377, ISO 1171)

Following completion of the testing, our clients are supplied with an official, accredited testing report summarising the full fire & technical characteristics.

If you are interested in dust testing, or have any questions, please contact us and we will be happy to help.

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