DSS087: Practical Considerations for Installing Explosion Protection Systems with Ric Smith

In this episode of the DustSafetyScience Podcast, EHS manager Ric Smith is sharing some insightful and practical considerations for installing explosion protection systems.

Ric, a former emergency care nurse who transitioned to an environmental health and safety role at a corn milling facility, talked about a dust explosion that occurred there in Episode #86. In this interview, he shares more of his professional and practical knowledge of combustible dust safety by answering the following questions:

What protection system types have you installed and managed?
Did you ever do a live test of a system?
What were the ongoing maintenance processes?

What protection system types have you installed and managed?

Ric has worked with protection systems for dust collectors, bucket elevators, and conveying systems. Most of the baghouses had explosion venting: if there was an event, it would vent outside.

More recently, he was involved in the installation of three newer systems, one of which was installed near a stairwell. The bucket elevator was located within the building, away from exterior walls, and the headhouse and boot put terminated inside the facility.

As part of the design team, Ric was required to identify all necessary requirements for the system. There was no fire suppression, which was acceptable under the NFPA standards for 2012, but at that time (2018), the 2017 versions of NFPA 68 and 69 were being adopted, which meant that fire and deflagration suppression systems would be necessary.

“Now, it’s easier to do that before you implement the process and not retroactively, as we all know from our prevention through design,” Ric said. “So unfortunately, though, I added on another couple hundred thousand dollars to the project because of that. But it’s a life safety code and we had to do it.”

Ric and his team started researching appropriate system types, bearing in mind that the facility was in the food industry. Although food grade suppressants would be more expensive, it was a smaller cost than the one that the company would incur if it lost all the material in the elevator.

Ric noted that one factor in the final decision was the type of product going through. Whole kernel corn and powdered corn have properties that impact the length of the bucket elevator. If the product travels a considerable distance, you may have to install cartridges and canisters in the middle of the length, and one of the systems traveled for six floors, so it required an extra canister.

They opted for suppression systems that used light sensors to detect evolving incidents, but were soon concerned that it might be triggered by shining a flashlight into an area where the sensor might pick it up.

“We had an inspection chamber there and some light probes that operate and tell you that there’s product flowing through the bucket elevator,” Ric said. “Well, with that being within four feet of the sensors, there’s the potential for it to be discharged.”

There were, he explained, costs associated with a discharge.

“If these high-pressure chambers go off accidentally, it’s $20,000 to reset them. Potential loss of product, either within the elevator or whatever bin it goes into, can raise the cost to $50,000. You also have to spend time and effort cleaning it out. We wanted to be very sure that we would prevent an accidental discharge.”

They had to run their own tests, because their chosen manufacturer was not sure that kind of light would set the system off.

“They couldn’t tell us if it was going to be normal flashlights, normal LED light bulbs or what have you. So we (did) our own testing. The lights in that particular facility were the old yellow lights that you see in a lot of buildings, and would trigger the discharge of the HPD canisters. So we changed the lights in the building, particularly around these areas where or it might occur. And we went with the LED and more energy-efficient lights, so that became better, too.”

Ric and his team restricted the controls to maintenance personnel because they were familiar with programmable logic, and added some computer modules that, if the system was shut down, issued a notice that there had been a discharge so that they could observe the fallout sequence.

“Of course, it’s not completely failsafe,” Ric conceded. “But it’s helpful that we can try to minimize any accidental discharge that might occur.”

He recalled that there were a couple of locations where the gauges fell low. They called a technician, who determined that the canisters being used had a structural defect that caused them to leak.

“They came out, they changed it out, and it wasn’t a big deal. But it was fortunate that we had the monitoring devices where somebody picked up on the gauge. We also had sensors in the computer system that said that there was a low pressure. And so those are important monitoring components that we need to ensure the safety of the designs.”

Did you ever do a live test of a system?

Ric said that he did a live test of the light sensor system using a standard flashlight with a yellow wavelength. Everything was set up normally, the sole exception being that the bottles were disconnected. When they triggered the system, they created a video of the outcome for their training library.

“We videoed how we triggered it, what kind of alarms we would see both on the computer panel and the system control panel, because there are separate systems that interact with each other. That video really helped out with onboarding maintenance folks as well as operators and sanitation. They understood what it meant to lock out a system that is highly sophisticated and designed to be very impactful for preventing any fires, explosions, et cetera. And with it being new, a lot of the managers there weren’t aware of it either.”

He insisted that the installer be present during the live test to help out with any troubleshooting, and arranged for them to come out every quarter to confirm that the system was working properly. Then, as facility personnel got more familiar with the system, it could be turned over to maintenance personnel.

What were the ongoing maintenance processes?

The buckets in this particular elevator were only four inches square, making regular maintenance necessary. They had to first lock out the top and bottom to prevent any accidental discharge, which required a fair amount of advance preparation.

“You just can’t shut her down right away and start working. You have to really be diligent about how you’re going to do your maintenance work on the equipment. You can’t go under the assumption that one bucket elevator is the same as the other bucket elevator. We have one that was installed 20 years ago and a new one. So what’s the difference between the two? That often becomes the question as well.”

Conclusion

When asked how he discussed costly but necessary equipment and upgrades with facility management, Ric said, “I try to persuade through stories. Within our facility, we can tell stories and apply them to real-life situations. We can show pictures and highlight what a Magnehelic pressure of zero means versus a three to five range versus a 10. I always like to turn safety into business acumen. If we can address the safety quality production tripod, then I think we’re more successful at making change.”

If you would like to discuss further, leave your thoughts in the comments section below. You can also reach Ric Smith directly:
Email: [email protected]

If you have questions about the contents of this or any other podcast episode, you can go to our ‘Questions from the Community’ page and submit a text message or video recording. We will then bring someone on to answer these questions in a future episode.