Page 10 - OHS, September 2021

COMBUSTIBLE DUST
Dust is created when materials are transported, handled, processed, polished, ground and shaped. Dust can also form from abrasive blasting, cutting, crushing, mixing, sifting or screening dry materials.
following fifive factors are present:
■ Fuel, in the form of dust particles
■ Dispersion of the fuel in the form of a dust cloud
■ Oxygen in the form of air
■ Confinement of the dust cloud in the form of a container
(e.g. a dust collector)
■ A source of ignition
There are several ways dispersion can occur, such as a dry filter
being pulse cleaned or from an initial explosion in processing equipment, causing a blast wave that disturbs accumulated dust that, if ignited, causes a secondary explosion. The latter is often far more destructive than a primary explosion due to the increased quantity of dispersed dust.
Monitoring Dust Concentration to Mitigate Risks
Undertaking a walk-through survey using a hand-held, real-time sampler can provide an instant indication of dust concentration. It can also be used to check the effectiveness of control measures, for example, a local exhaust ventilation pre and post filter.
Industrial hygienists may already be undertaking personal monitoring for toxic or sensitizing dusts. If so, the same air- sampling pump can be used in combination with a real-time sampler when housed in a robust, portable case, on an unattended, short-term basis. Such a system can provide concentration using a gravimetric filter but also a time history profile, which could help identify the source of the problem.
Fixed, AC powered solutions can also be used on a continuous basis for high-risk areas. These have the advantage that the data can be made available remotely using a web-based interface. These systems provide real-time alerts via text message or email should limits be exceeded. Reports can be automated and sent to multiple users, allowing for early intervention to avoid potential problems.
However, great care should be taken in hazardous atmospheres that may require instrumentation to be intrinsically safe or require a hot-work permit. Action thresholds should always be set at a fraction of the Lower Explosion Limit (LEL) for the dust in question. If there is any doubt whatsoever, employers should seek
advice from the relevant site manager or supervisor responsible for the risk assessment.
Personal Protection at Work
A personal air sampling pump is a bodily worn pump used to sample for airborne contaminants that can be damaging to health. With the ability to provide real-time data about dust levels, identifying harmful areas of exposure, personal air sampling is an effective method to mitigate risks.
Before implementing any monitoring solution, a risk assessment should be conducted to answer some key questions: Who is exposed and to what? How long are they exposed for? How much are they exposed to?
Personal monitoring with an air sampling pump must be practical and operate in a way that it does not disrupt the comfort or productivity of a worker. Pumps can operate at a variety of different flow-rates and are designed to be clipped to the wearer’s belt. A slim, ergonomic design is the ideal solution, as it is non- obtrusive to the wearer allowing him/her to carry on with their job whilst being monitored.
Personal sampling instruments highlight exactly when and where excessive dust levels are occurring to support decision- making. Personal monitoring results equip employers and employees alike with greater knowledge that can contribute to a positive workplace health program. Consequently, personal monitoring enables a better understanding of how to protect workers from exposure through changing health and safety procedures and supplying appropriate respirable protection during dangerous tasks.
For harmful substance, crystalline silica for instance, personal monitoring is essential, and employers must employ personal dust sampling pumps in order to assess and control exposure effectively. Integrating monitoring pumps should become an established part of the health and safety process for companies. As a result, companies save valuable time while protecting employees, which enhances business efficiency.
Why Employers Need to Understand the Hazards
Dust explosions continue to be a persistent problem for many industries resulting in loss of life, injuries and destruction of property. Even highly trained individuals including government enforcement officials, insurance underwriters and company safety professionals often lack awareness of combustible dust hazards. Material Safety Data Sheets (MSDS) are also ineffective in communicating to employers and workers the hazards of combustible dust explosions and ways to prevent them. This is all the more reason for all employees to have a basic awareness of the hazards of dust explosions and the best way to mitigate those risks.
Tim Turney is the Global Marketing Manager at Casella. REFERENCES
1. https://www.cdc.gov/niosh/docs/wp-solutions/2019-113/pdfs/2019- 113.pdf?id=10.26616/NIOSHPUB2019113
2. https://www.cdc.gov/niosh/injury/fastfacts.html
3. https://ops.fhwa.dot.gov/weather/q1_roadimpact.htm
10 Occupational Health & Safety | SEPTEMBER 2021
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