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Safeguarding Your Workspace: Strategies to Prevent Industrial Dust Collector Explosions
NFPA classifies dust according to its potential explosibility, known as the Kst value, as follows:
• ST0: Kst value of 0 = not explosive.
• ST1: Kst value below 200 = weak to moderately explosive.
• ST2: Kst value from 200 to 300 = strongly explosive.
• ST3: Kst value exceeds 300 = very strongly explosive.
In addition, OSHA provides guidance on combustible dust explosion hazards and notes, “In many combustible dust incidents, employers and employees were unaware that a hazard even existed. It is important to determine if your company has this hazard, and if you do, you must take action now to prevent tragic consequences.”
Explosion Protection Solutions for Dust Collection Systems
Let’s explore a few explosion protection devices and systems designed to ensure dust collection systems meet NFPA standards. Active systems aim to prevent explosions by detecting and responding to them before or during an incident. In contrast, passive systems activate in response to an explosion, focusing on controlling the event to safeguard employees and reduce equipment damage.
Active Devices
• Chemical isolation systems are installed in inlet or outlet ducting to react within milliseconds of detecting an explosion. These systems typically consist of an isolation canister, explosion pressure detectors and a control panel. By creating a chemical barrier, they suppress the explosion within the ducting, halt the spread of flames and minimize the pressure surge that could affect process machinery connected to the dust collector.
• Chemical suppression safeguards the dust collector itself. It is often used in conjunction with chemical isolation when safe venting of an explosion is not feasible or when the dust is hazardous or toxic. The system rapidly detects an explosion hazard, triggering the release of a chemical agent that promptly extinguishes the flame before an explosion can occur.
• Fast-acting valves, which close within milliseconds of detecting an explosion, can be installed in inlet or outlet ducting. These valves form a physical barrier within the ducting, effectively isolating pressure and flame fronts from either direction, preventing them from spreading further through the process.
This article originally appeared in the September 2024 issue of Occupational Health & Safety.