DUST TESTING PARTICLES FOR HAZARDOUS CHARACTERISTICS
Explosion tests for DSEAR
By testing the particles of the material being processed, we can better determine suitable protection measures against explosions. Often, dust testing is the first stage when it comes to ensuring your site is fully protected and ATEX/DSEAR compliant.
The dusts will have different explosive properties that contribute to the hazardous nature of the material. These might be self-heating (leading to spontaneous combustion), rapid spread of fire, high ST classification (strong or very strong explosion class), sensitivity to electrostatic spark ignition or low ignition temperature.
The certified laboratory undertakes dust testing work for a wide range of companies and industries, such as pharmaceutical and chemical products, coal dust, grain dust, foods products such as flour and sugar, wood products produced by the particle board industry, sawdust, metal dusts and increasingly biomass fuels and dried waste from the water treatment industry.
We are a UK based company offering a full range of dust testing to determine the hazardous properties of particulates. For those materials where the explosive nature of the dust is in doubt, our classification test to EN ISO/IEC 80079-20-2 exposes the material to 4 different ignition sources to determine flammability; 10KV electric spark ignition, hot coil ignition, high temperature ignition at 1000 degrees Centigrade and using electrically operated chemical igniters in a pressure vessel. The classification test is the essential first step in explosibility testing.Our experienced laboratory staff can advise on which tests are required to ensure your company complies with ATEX or DSEAR.
EN, UN & ASTM Testing Standards
The majority of our dust explosion tests and dust ignition tests are carried out to UK, European and ISO international standards. However, some tests are available to US (ASTM) standards – please contact us for further details.By better understanding the explosion hazard and nature of the combustible dust, suitable preventative and protective measures can be employed to mitigate the risk – see our guide to DSEAR for further details.
CLASSIFICATION TEST
EXPLOSION INDICES TEST (Kst & P max)
MINIMUM IGNITION ENERGY (MIE)
MINIMUM IGNITION TEMPERATURE (MIT)
SEE ALL TESTS
CLASSIFICATION TEST
Hazard classification test for combustible dust
The classification test offers a qualitative assessment of whether or not a suspended dust cloud is capable of initiating and sustaining an explosion in the presence of four different ignition sources; 10kV electric spark, hot coil, 1000°C hot surface, and low energy chemical igniters.Explosion testing for hazard classification is made on a visual observation of flame propagation in the first two tests and on explosion pressure increase for the chemical igniters in an enclosed volume.
The test is carried out to EN ISO/IEC 80079-20-2:2016 Explosive atmospheres – Part 20-2: Material characteristics — Combustible dusts test methods and results in one of two possible outcomes:
Group A (hazardous) – the dust cloud propagates flame from the ignition source and is classed as a combustible and potentially explosible material.
Group B (non hazardous) – the dust cloud does not propagate flame from the ignition source and is classed as a non-combustible material.
Group A dusts (combustible) may form Zone 20, Zone 21 and Zone 22 hazardous areas, depending upon the frequency and duration of the explosive atmosphere.
EXPLOSION INDICES TEST (Kst & P max)
Explosion indices test (Kst value and P max)
Dust explosion classes ST1, ST2 & ST3
Kst value and Pmax are explosive properties measured in the laboratory to quantify the severity of a dust explosion. The explosion indices test follows EN 14034-1:2004 (determination of the maximum explosion pressure Pmax of dust clouds) and EN 14034-2:2006 (determination of the maximum rate of explosion pressure rise of dust clouds Kst). The tests are carried out in a 20 litre sphere apparatus which reproduces a high state of turbulence to simulate worst case process plant conditions.
A weighed quantity of combustible dust is placed into the dust container. The main explosion chamber is then evacuated to 0.4 bar absolute. An automatic test sequence is initiated to pressurise the dust container to 20 bar gauge, and then the fast acting valve on the dust container outlet is opened to allow material into the explosion chamber.
The rebound nozzle ensures an even distribution of dust within the explosion chamber and the control system activates two 5 KJ chemical igniters at the centre of the sphere 60 ms after the dust has been dispersed. Explosion pressures are measured for a range of dust concentrations using piezo-electric pressure transducers. The tests are carried out over three series to ensure a thorough investigation of the explosion properties. From the tests, the arithmetic mean of the maximum values (both maximum pressure and maximum rate of pressure rise) is obtained.
The Kst value is calculated as the equivalent pressure in a 1 m3 sphere from the cube law (Kst value = cube root of volume x explosion pressure rise).
The ST class is based on the Kst value as follows:
ST class 0 – Kst value = 0
ST class 1 – Kst value less than 200 bar m/sec
ST class 2 – Kst value between 200 and 300 bar m/sec
ST class 3 – Kst value greater than 300 bar m/sec
Explosion testing for Kst value & Pmax is essential to validate protection design (explosion venting, explosion suppression and explosion containment).
MINIMUM IGNITION ENERGY (MIE)
Testing for minimum ignition energy (MIE)
Dusts sensitive to ignition by electrical spark
The minimum ignition energy (MIE) test measures the ease of ignition of a dust cloud by electrical and electrostatic discharges. The test is carried out according to EN ISO/IEC 80079-20-2:2016 (Explosive atmospheres Part 20-2: Material characteristics – Combustible dusts test methods).
The MIE apparatus consists of a borosilicate tube placed over a dispersion cup and fitted with two electrodes. The electrodes are connected to a circuit that produces an electrical spark of known energy. A weighed sample of combustible dust is placed in the dispersion cup, which is blown up through the tube with compressed air past the ignition source. If flame propagation is observed, the energy of the spark is reduced until no flame propagation is seen for 10 consecutive tests. At that spark energy, a range of dust sample weights is tried to thoroughly investigate potential dust explosion concentrations.
The test result is stated as an energy range, indicating that ignition took place at the higher value and no ignition took place at the lower value. The MIE is a measure of how sensitive an explosive dust cloud is to electrical spark ignition. Testing for minimum ignition energy gives guidance on whether ignition by electrostatic discharge from plant personnel or process conditions is likely to occur in practice.
MINIMUM IGNITION TEMPERATURE (MIT)
Minimum ignition temperature (MIT)
Minimum ignition temperature of a dust cloud
The minimum ignition temperature (MIT) is the lowest temperature of a hot surface that will cause a dust cloud, rather than a dust layer, to ignite and propagate flame. The test follows EN ISO/IEC 80079-20-2:2016 (Explosive atmospheres Part 20-2: Material characteristics – Combustible dusts test methods).
Approximately 0.1 g of combustible dust is placed in a dust holder at the top of a temperature controlled furnace with an open bottom. The dust is dispersed by compressed air downwards past the hot surface of the furnace to see if ignition occurs and flames are produced. If the dust does not ignite, the furnace temperature is increased and the test repeated until ignition of the dust occurs.
Once ignition has been established, the mass of the dust sample and injection pressure are varied to find the most vigorous explosive flame discharge. The temperature of the furnace is then reduced incrementally until flame propagation is no longer observed. At this temperature, the dust mass and injection pressure are varied to confirm that no ignition is found over ten consecutive tests. The minimum ignition temperature (MIT) is the lowest temperature of the furnace at which flame is observed minus 20°C for furnace temperatures over 300°C or minus 10°C for furnace temperatures under 300°C.
For items of plant such as driers, testing the minimum ignition temperature is important to prevent a dust explosion occurring through contact with a hot surface. The internal temperature is generally limited to two thirds of the MIT when measured in degrees Centigrade. For example, a dust with a MIT of 450°C would require a maximum operating temperature in the drying process of 300°C, giving a safety margin of 150°C.
SEE ALL TESTS
We offer a large scope of dust testing options, such as:
Layer Ignition Temperature (LIT)
Limiting Oxygen Concentration (LOC)
Lower Explosible Limit (LEL)
Isothermal Basket Test
Burning Behaviour (BZ)
Powder Volume Resistivity
To find out about all the testing options available and to speak with our dust testing specialist, click here or contact us below and we will be happy to handle your enquiry.
Safety, the cornerstone of any successful business operation, is significantly enhanced through thorough dust testing. By identifying the explosive properties of the dust particles in your environment, such as minimum ignition temperature or energy sensitivity you’re equipping yourself with the necessary knowledge to enforce preventive measures, effectively reducing the risk of accidents. This proactive approach not only safeguards human lives but also prevents catastrophic damage to infrastructure and equipment.
Moreover, the financial implications of dust testing are noteworthy. Yes, it is an upfront investment; however, the potential long-term cost savings are substantial. Imagine the financial repercussions of an industrial accident – the damage to equipment, the downtime, not to mention potential legal liabilities and fines for regulatory non-compliance. By investing in dust testing, you’re not just buying peace of mind; you’re making a wise business decision.
In essence, dust testing is not just about compliance with regulations; it’s about fostering a culture of safety and efficiency. Your employees, stakeholders, and bottom line will thank you for it.
What are the standards and regulations relating to dust testing, ATEX and DSEAR?
When maintaining safety in workplaces with explosive atmospheres, two significant guidances come into play – ATEX and DSEAR. These are crucial lifelines that can mean the difference between a safe, productive work environment and a potentially disastrous one.
ATEX – this term hails from the French “ATmosphères EXplosives”. It comprises two European directives that are of paramount importance for industries operating in explosive atmospheres. The first, Directive 99/92/EC (ATEX 137), focuses on the safety of workers and sets the minimum requirements for health and safety protection. The second, Directive 2014/34/EU (ATEX 95), governs the equipment and protective systems designed for use in such volatile atmospheres.
You’re in an industry dealing with flammable gases or dust. A slight oversight could lead to catastrophic consequences. ATEX regulations act as a safeguard, ensuring that the equipment you use and the protective measures you have in place are sufficient to prevent such incidents.
In the UK, the DSEAR, or the Dangerous Substances and Explosive Atmospheres Regulations 2002, is how ATEX is enforced. It implements the same directives as ATEX but integrates elements from the Chemicals Agents and the Carcinogens or Mutagens Directives. DSEAR’s mandate is clear – employers must control safety risks stemming from fires, explosions, and substances that are corrosive to metals.
So how can Dust Testing comply and navigate these complex regulations? Our services play a key role in ensuring compliance with both ATEX and DSEAR. We delve into the explosive properties of the dust in your workplace. Dust testing is the first step to understanding the risk and provides useful parameters in mitigating that risk. Through meticulous testing, we can identify key characteristics like the minimum ignition energy or temperature. Armed with this knowledge, you can implement control measures that are tailor-made for your unique environment.
In summary, dust testing is your map to regulatory compliance and workplace safety.
What tests do I need?
If the flammability of the dust / powder is unknown, start with a classification test. If the powder is classified as combustible, then consider the following tests based upon potential ignition sources etc:
How could dust be ignited in the process?
Test
Action
Hot surface
LIT for dust layers
MIT for dust clouds
Specify equipment surface temperature limits including a safety margin
Electrostatic spark
MIE
Influences the choice of plant materials (conductors / non conductors) earth bonding and personnel antistatic precautions
Self heating
Screening test
Specifies maximum storage size and configuration storage temperature and storage time
What is the best way to avoid an explosive atmosphere?
Test
Action
Dust control
LEL
Plant should be operated with low level of dust present e.g. use dust suppressed materials
Oxygen control
LOC
Plant should be operated under an inert gas e.g. nitrogen. An operational safety
margin is required, based upon the inert
gas control system and plant layout
How can the plant be made safe?
Test
Action
Explosion venting
Explosion indices
Kst and Pmax
Verify vent design is adequate for the
materials being handled
Explosion suppression
Explosion indices
Kst and Pmax
Verify suppression design is adequate for the materials being handled
Explosion containment
Explosion indices
Kst and Pmax
Verify explosion containment and
explosion isolation design is adequate for the materials being handled
The following data should be regarded as essential, safety critical information:
Classification test
where the flammability of the dust is not known
LOC
where inerting is the basis of safety
Explosion indices (Pmax & Kst)
where explosion protection is the basis of safety - i.e. explosion venting, explosion suppression or explosion containment
MIT
for all plant where a dust cloud may come into contact with a high temperature surface, such as a dryer
LIT
for all plant where dust may accumulate on any surface that may get hot through electrical or mechanical energy such as an electrical motor or gearbox
MIE
for all plant, particularly where electrostatic ignition is possible
Self-heating screening test
for any material that is suspected of being capable of self-heating.
Dust explosion testing involves determining the hazardous properties of particulate materials. This helps to understand the risk of dust explosions in various industries and implement appropriate protection measures. The tests often use four different ignition sources to assess the flammability of the dust.
Many industries require dust explosion testing, including pharmaceuticals, chemicals, coal, grain, food (like flour and sugar), wood products, metal dusts, biomass fuels, and the water treatment industry, to name only a few.
There are several types of dust explosion tests, including Hazard Classification Tests, Explosion Indices Tests (Kst value and Pmax), Minimum Ignition Energy (MIE) Tests, and Minimum Ignition Temperature (MIT) Tests.
A Hazard Classification Test is a qualitative assessment to determine if a suspended dust cloud can initiate and sustain an explosion when exposed to different ignition sources. The outcomes classify the material as either Group A (hazardous) or Group B (non-hazardous).
The Explosion Indices Test measures the severity of a dust explosion. This test calculates the Kst value and Pmax, which represent the maximum explosion pressure and the maximum rate of pressure rise, respectively. These tests are carried out in a controlled environment that simulates process plant conditions.
The MIE Test measures the ease of ignition of a dust cloud by electrical and electrostatic discharges. The test result indicates how sensitive an explosive dust cloud is to electrical spark ignition, providing guidance on the likelihood of ignition from electrostatic discharge in practice.
Dust explosion testing is crucial for understanding the explosive properties of dust from various materials. By testing these particles, we can better determine suitable protection measures against explosions, ensuring that your site is fully protected and compliant with safety regulations like ATEX and DSEAR.
Dust explosion tests are performed in a certified laboratory under controlled conditions. For example, in an Explosion Indices Test, a specific quantity of combustible dust is placed into a chamber, and an automated sequence is initiated to pressurise the chamber and ignite the dust.
Most dust explosion tests are carried out to UK, European, and ISO international standards. Some tests are also available to US (ASTM) standards. These standards ensure that the testing procedures are reliable and the results are accurate.
CONTACT US
We are waiting to discuss your explosion safety requirements, so don’t hesitate to get in touch. Whether you would like to receive a quotation or you are just looking for more information on dust testing, we are here to help.
Email
sales@coopatex.co.uk
Phone
0208 243 8914
We use cookies on our website to give you the most relevant experience by remembering your preferences and repeat visits. By clicking “Accept All”, you consent to the use of ALL the cookies. However, you may visit "Cookie Settings" to provide a controlled consent.
This website uses cookies to improve your experience while you navigate through the website. Out of these, the cookies that are categorized as necessary are stored on your browser as they are essential for the working of basic functionalities of the website. We also use third-party cookies that help us analyze and understand how you use this website. These cookies will be stored in your browser only with your consent. You also have the option to opt-out of these cookies. But opting out of some of these cookies may affect your browsing experience.
Necessary cookies are absolutely essential for the website to function properly. These cookies ensure basic functionalities and security features of the website, anonymously.
Cookie
Duration
Description
cookielawinfo-checkbox-analytics
11 months
This cookie is set by GDPR Cookie Consent plugin. The cookie is used to store the user consent for the cookies in the category "Analytics".
cookielawinfo-checkbox-functional
11 months
The cookie is set by GDPR cookie consent to record the user consent for the cookies in the category "Functional".
cookielawinfo-checkbox-necessary
11 months
This cookie is set by GDPR Cookie Consent plugin. The cookies is used to store the user consent for the cookies in the category "Necessary".
cookielawinfo-checkbox-others
11 months
This cookie is set by GDPR Cookie Consent plugin. The cookie is used to store the user consent for the cookies in the category "Other.
cookielawinfo-checkbox-performance
11 months
This cookie is set by GDPR Cookie Consent plugin. The cookie is used to store the user consent for the cookies in the category "Performance".
viewed_cookie_policy
11 months
The cookie is set by the GDPR Cookie Consent plugin and is used to store whether or not user has consented to the use of cookies. It does not store any personal data.
Functional cookies help to perform certain functionalities like sharing the content of the website on social media platforms, collect feedbacks, and other third-party features.
Performance cookies are used to understand and analyze the key performance indexes of the website which helps in delivering a better user experience for the visitors.
Analytical cookies are used to understand how visitors interact with the website. These cookies help provide information on metrics the number of visitors, bounce rate, traffic source, etc.
Advertisement cookies are used to provide visitors with relevant ads and marketing campaigns. These cookies track visitors across websites and collect information to provide customized ads.