In this episode of the DustSafetyScience Podcast, we are interviewing Jason Krbec, Engineering Manager at CV Technology based out of Jupiter, Florida, about passive explosion mitigation through deflagration venting.
Jason has over 10 years of experience working in dust explosion protection and prevention. He’s a member of the American Society of Safety Engineers and several NFPA technical committees. Jason will also be presenting at the 2020 Digital Dust Safety Conference on traditional and non-traditional explosion venting options.
In today’s episode, he answers questions like the following:
- What is the principle behind explosion venting?
- What are some advantages of explosion venting compared to some other mitigation techniques?
- What should NOT be done with explosion vents?
- What role do third-party approvals play?
- What is on the horizon for explosion venting technology?
- What processes are ideal for flameless venting?
What is the Principle Behind Explosion Venting?
Everyone has probably seen a video or a photo of a big fireball coming out of a vessel. This is explosion deflagration venting in action. It is a passive mitigation solution intended to prevent rupture of the vessel from happening. When a deflagration causes a pressure rise, a relief area opens to reduce the pressure to a manageable level, so the explosion does not occur.
What are Some Advantages of Explosion Venting Compared to Some Other Mitigation Techniques?
Jason explained that explosion venting is a passive type of mitigation technology.
He described active technologies as ones that typically use a sensor to detect the pressure rise associated with the deflagration. There can also be a reaction involved, such as chemical suppression.
Passive solutions do not require a system to identify explosions: they simply open at a preset pressure, whether it’s for a deflagration event, an explosion event or a process reason. Their biggest advantage is that they are always ‘on’: there are not a lot of failure modes for explosion vents.
In Episode #29, Timothy Heneks talked about the concepts of safety instrumented systems (SIS) and safety integrity levels (SIL). Jason explained that there are requirements in the new NFPA 69 that covers some of these prevention systems. Starting November 5th, 2021, prevention systems will have to be treated like a SIS.
This is where passive technology really comes into play: it’s readily available and high safety integrity levels can be reached with solutions that involve venting.
What Should NOT be Done with Explosion Vents?
Vents are frequently modified to meet the needs of the surrounding processes. Hygienic membranes are available for food, pharmaceutical, or chemical industries. Auto-closing doors and other options are also available.
The key is to have an experienced manufacturer provide these add-ons, but some managers apply their own solutions. At some facilities, for example, vents have bars placed over them or are painted over. Jason recommended that facility managers talk to companies like CV Technology about concerns like animal access, as bird screens are available to keep animals out of the ductwork.
What Role Do Third-Party Approvals Play?
According to Jason, third-party approvals come into play with technologies like flameless venting. They confirm that the device is designed to accommodate its intended purpose. NFPA 68 and certain ATEX test standards cover some of these explosion venting devices.
Flameless venting is the same basic concept as venting. A deflagration vent is mounted on a piece of equipment with a flame arrester attached. The goal of that flame arrester is to make sure that the flame ball does not exhaust into an area that may be occupied by people or other process area equipment.
Third-party approvals come into play when devices like these are added to venting. For example, if there is too much dust on a flameless vent, it affects efficiency. With a flame arrester in the back of the explosion vent, it doesn’t relieve 100% anymore, so third-party approvals for KST are really important. The KST and Pmax values of the dust can affect flameless vent operations.
What is on the Horizon for Explosion Venting Technology?
Jason said that the technology is moving from control designs with less engineering to those that are highly precise.
“Tight tolerance is really, really important when designing vents,” he said.”This gets into a conversation really about keeping your process up and running. If you’re running a process and you put an explosion vent in, it’s a passive solution. You went for that passive solution because it’s the safest solution, the most reliable solution. And yet you put it in with the goal of set it and forget it. Well, if you do that, you have to make sure that vent can hold up to process conditions.”
He identified sanitary designs as another big advance, especially for the food industry. Electro-polished metal, crevice-free designs, and USDA-certified designs are becoming more common, as no one wants their explosion vent to be the weak point in their food safety standards.
What Processes Use Flameless Venting?
Flameless vents deliver the benefits of passive venting in areas that would be normally occupied or lack a clear path let let the fireball out. They can be placed on dust collection equipment, pneumatic conveying equipment, storage vessels, and mechanical conveying equipment like bucket elevators. Third-party certification is typically used to ensure that a flameless vent is acceptable for the dust concentration of its surroundings.
According to Jason, the one downside to flameless venting that some can have some gas from combustion enter a room or occupied area, so managers need to pay attention to the carbon monoxide production of combustion material. Some materials, like certain plastics, give off toxic gases when they combust, so indoor flameless venting would not be advisable in such an application.
Conclusion
Passive venting is a technology that can enhance safety in most environments. There is no ‘one size fits all’ approach, however: the best solutions are designed using a combination of current safety standards and the unique requirements of each location.
If you would like to discuss further, leave your thoughts in the comments section below. You can also reach Jason Krbec directly:
Tel: 561-318-4051
Email: [email protected]
LinkedIn: https://www.linkedin.com/in/jason-krbec-5304b657/
Website: https://cvtechnology.com/
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.
Resources Mentioned
DustSafetyScience
Combustible Dust Incident Database
DustSafetyScience Podcast
Questions from the Community
2020 Digital Dust Safety Conference
Companies
CV Technology
Previous Podcasts
DSS028: Recent changes to NFPA 69 Standard on Explosion Prevention Systems with Timothy Heneks
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DSS067: Passive Explosion Mitigation Through Deflagration Venting with Jason Krbec
