DSS168: Manufacturing Safety Alert: Backdraft Damper Stuck In Open Position

In today’s episode of the Dust Safety Science podcast, we cover a manufacturing safety alert put out by the BC Forest Safety Council and the Manufacturing Advisory Group, or MAG Group, based in BC It specifically addresses backdraft dampers being stuck in the open position, causing a backdraft of fine dust onto a planer.

Manufacturing safety alerts are put out through BC Forest Safety Council (BCFSC) in conjunction with the Manufacturing Advisory Group in British Columbia. Any incidents, any events, any work issues that facilities have encountered are submitted anonymously to the central system. The BC Forest Safety Council sends these out to its newsletter subscribers, along with recommended actions and takeaways to prevent similar events in the future.

We covered an example of one of these incidents back in Episode #105. We did a Safety Share testing of high-speed abort gates with Corey Gardiner and reviewed some issues that they found when they were testing their high-speed abort gates and the abort gates didn’t close properly.

The Incident

This incident involved a dust collection system connected to a planer. When they turned off the power during a power reset, it resulted in a backdraft of fine dust into the planer system.

Nothing happened. No fire happened. No explosion happened. It just caused fine particles to backdraft flow into the planer system, so it’s a near-miss. If something had ignited, a fire might have happened. There could also have been a respiratory hazard. There are many reasons why we don’t want this to happen when you turn off the power to the system.

The incident occurred because the backdraft damper on the system failed to close when the blower was shut off. The blower was creating positive pressure through the ducting back to the dust collector, so when the system was turned off, the backdraft damper should have closed and stopped that dust from back-drafting back into the planer system. It didn’t.

There are a few reasons why this may have happened. An inspection of the backdraft damper showed that it may have been frozen in the open position. The bearings were also quite stiff and the counterweight on the backdraft damper was also potentially out of position. All three of these factors resulted in the damper not closing when the power to the system was shut off and the positive pressure from the blower stopped.

Takeaways

So there were some important takeaways from this incident. One was to update the monthly preventive maintenance to include lubricating the backdraft damper swivel bearings. It was also recommended that, before startup, workers verify that the backdraft damper gate is fully functional, especially after prolonged weekends in cold weather, and also investigate the possibility of automatic sensors that sound an alert if the dampers fail.

The most important takeaway they highlighted was to develop a start-up inspection of the ventilation equipment to confirm that all safety systems are operating before turning the system back on.

Should This Incident Be Treated as a Near Miss?

It’s probably a good idea to treat something like this as a near-miss at your facility and ask some “what-if” style questions.

Can this happen while the planer is running? That may be an ignition source.
What are some other ways that the damper might fail to close?
When can the suggested actions fail? In this case, the most important takeaway was the administrative control- to develop a start-up inspection and potentially add engineering controls like a sensor alarm if the damper fails. But when might these actually fail themselves? And what would be the outcome?
When could there be potential ignition sources present?
What would happen if this actually occurred during an active fire or an upset condition at the facility?
Are there people in the vicinity?
How serious could this have been?

This near-miss could have been a lot worse. It is important to ensure proper precautions to prevent a future occurrence.

Conclusion

The manufacturing safety alerts force us to ponder uncomfortable questions. Could this happen here? Could this happen in my facility? Could this happen with my equipment? If you’re operating backdraft dampers or similar types of equipment that need to close in order to function on the ducting line, these are considerations that you might need to address to make sure they function properly the next time they’re called into action.

Again, treat this as a near-miss or a pre-accident investigation. Look at how you could evaluate and improve these systems so that they are resilient against this type of hazard happening again.