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Combustible Dust Awareness

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Combustible Dust Awareness

■ Is my dust combustible?▪ Fugitive Dust vs Process Dust

▪ Standards NFPA68, AS NZS4745:2012

■ ‘Its only a little bit of dust’▪ 200 grams per day, 1 kg per week

▪ How often do you empty your dust collector?–20 ltr collection bin, at a bulk density of 600,

half full container is 6 kg of dust.

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• Test Safe – Sydney

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Combustible Dust Awareness

■ The first documented dust explosion occurred in a Turin, Italy, bakery in 1785.

▪ The explosion was caused by the ignition of flour dust by a lamp in a bakery storeroom.

▪ It lead to the realization that grain dust is a highly explosive substance that must be handled carefully.

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Deflagration – the perfect storm

There are 5 components required for an explosion to occur.1. Fuel Source2. Oxygen3. Dispersion4. Confinement5. Ignition source

Combustible Dust Awareness

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Combustible Dust Awareness

■ Determining Combustible Dust Indices

■ Risk Assessment of application

■ Test vs Database▪ Simtars (Brisbane) approx. $5,500 per dust test

▪ http://staubex.ifa.dguv.de/?lang=e– Institute for Occupational Safety and Health of the

German Social Accident Insurance

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• Some terminology

• Kst – a tested value for dust, the maximum rate of pressure increase at deflagration in a 1 mtr vessel.

• St rating – a way of categorising Kst values• St1 – a dust with a tested Kst within the range Kst1 to Kst199

– Example, wood dust 95, soap 111, sugar 132, polyethylene 134, printer toner 196.

• St2 – a dust with a tested Kst within the range Kst200 to Kst 299– Example, polyester 237, wood flour 224, paint powder epoxy 202,

corn flour 200

• St3 – a dust with a tested Kst of 300 or above– Example, magnesium 508, aluminium powder 300, ’hybrids’

• LEL – lower explosion limit, a concentration of dust g/m3 at which an explosion risk is increased.

• Example, aluminium dust 30 g/m3, wood 60 g/m3.

• A dust concentration of 25% or less LEL is considered safe.

• Pmax – the maximum overpressure occuring within the test vessell in the event of deflagration.

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Any dust with a Kst greater than zero is risk.

Fine dust particles (under certain conditions) present an explosion hazard when suspended in air.

Why are smaller particles higher risk?Surface area.Higher surface area allows the dust to burn faster

Eg. Wood dust can be St1 or St2 risk

Effect of Particle Size

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• Is wood dust explosive?

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Combustible Dust Awareness■ Imperial Sugar, Georgia 2008. 14 dead, 42 injured.

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Combustible Dust Awareness■ Pet Food Factory, Gunnedah NSW. 2003. No injuries.

Damage 1.5 km radius.

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Combustible Dust Awareness■ August 2, 2014 Kunshan, China.

Incident killed 44 at scene, another 31 died in local hospital. 146 total deaths, 114 injured.

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Combustible Dust Awareness■ Fuwa Engineering Manufacturing Company, Foshan,

China. Dec 31, 2014. 17 dead, 33 injured.

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Combustible Dust Awareness

■ SS Grandcamp, Texas 1947 – Ammonium Nitrate▪ Estimated 465 dead, atleast 3,500 injured

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Combustible Dust Awareness

■ SS Grandcamp, Texas 1947 – Ammonium Nitrate

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• Housekeeping

• Primary vs Secondary and Tertiary explosions

• Correctly sized and operating dust collection systems reduces airbourne dust, reduces risk.

• Contain the event within the collector, outside the workspace.

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Incidents■ Sugar Australia, Glebe NSW, 2004 – Sugar

■ Longwarry Food Pak, Victoria, 2012 – Milk Powder

■ Pet food factory, Arizona 2014 – 4 dead

■ Loxton College, SA, 2013 – Wood dust

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• What dusts are combustible?

Wheat Carrot Rice

Egg white Magnesium powder Zinc

Coal Cellulose Garlic

Epoxy Resin Vinyl Ascorbic Acid

Onion Powder Gluten Bronze

Cocoa Sugar ……………..

Soap ……. ……

Aluminium Polyethylene Polystyrene

And so on

And so on

And so on……..

What is a hybrid application?

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Explosion Isolation Flap

High-SpeedAbort Gate

ExplosionVents Spark

Detection

Dirty AirFrom Facility Clean Air

To Facility

Dust Collector

Fan

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Explosion Isolation Flap

High-SpeedAbort Gate

ExplosionVents Spark

DetectionFan

Dirty AirFrom FacilityPROTECTED

Clean AirTo FacilityPROTECTED

Dust Collector

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• Why choose Nederman products and Systemaire?

• Wide product range allows tailored solutions

• Engineered solutions develop bespoke products

• In house competency training in ATEX compliance and combustible dust awareness

• Local staff qualified for St1 and St2 applications

• Global presence and focus on safe solutions

• Familiarity with regulations and standards

• Process and products to comply with regulations and standards

• Combustible Dust Documentation (CDD)

• Knowledge sharing with client base

• Awareness and diligence for impact of secondary explosion

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Questions

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