Combustible dust analysis

Purpose

Determination of explosive characteristics for dusts is vital for many industries to comply with the user directive 1999/92/EC, linked to ATEX. The parameters achieved through testing can be used to dimension vent sizing, to specify maximum surface temperature that may be achieved on equipment to be installed and much more.

RISE have the most well-equipped laboratory in Sweden for analyzing combustible dust, with dedicated test engineers and researchers specialized in fire safety, explosions and risk assessment. We offer a wide range of services to help companies investigate and limit explosion hazards.

Combustible gases and fluids have known explosion properties which are stated in their material safety data sheets, but for dust and powder it is not as simple. Defining the explosive properties is vital to attain a safe plant design and operating conditions.

Method

Modified Hartmann tube:
ISO/IEC 80079-20-2
A yes/no method to determine if the dust is combustible or not. If ignition occurs further testing is recommended.

MIE – Minimum Ignition Energy:
ISO/IEC 80079-20-2, EN 13821
The minimum energy required to ignite an explosive atmosphere. Testing can be performed without increased inductance to simulate common electrostatic discharges or with increased inductance, corresponding to e.g. mechanical sparks or sparks from faulty electrical equipment.

MIT_dc – Minimum Ignition Temperature of dust cloud:
ISO/IEC 80079-20-2, EN 50281-2-1
The lowest temperature of a hot surface which will ignite an explosive atmosphere. The test measures at which temperature a dust cloud in contact with, for example, a hot pipe, will ignite.

MIT_dl – Minimum Ignition Temperature of dust layer:
ISO /IEC 80079-20-2, EN 50281-2-1
The lowest temperature where a dust layer resting on a hot surface will ignite. The test simulates dust gathered on equipment, for example, and at which surface temperature the dust will ignite.

p_max – Maximum explosion pressure:
EN 14034-1
The maximum explosion pressure attained in a 20 L sphere. Together with the rate of pressure rise these are essential data to be able to properly dimension vent sizing etc.

dp/dt and K_st – Maximum pressure rise rate and dust explosion constant (severity):
EN 14034-2
An indication of how fast the pressure rises in the 20 L sphere and the corresponding pressure rise in a 1 m³ vessel. This value is the basis for the St-classes.

LEL/MEC – Lower Explosion Limit:
EN 14034-3
Lower explosion limit/minimum explosive concentration of dust which is ignitable in atmospheric conditions.

Test of resistivity:
ISO/IEC 80079-20-2
An indication of the electrical conductivity of the dust. High resistivity equals low conductivity. The risk of accumulating electrostatic charges increases with increasing resistivity.

Deliveries

The result is summarized by RISE in a written report. The report is delivered in English.