In today’s episode of the Dust Safety Science podcast, Eyal Zadok, an international expert for electrostatic discharge based out of Northern Israel, talks about the ways that one can analyze the likelihood of an electrostatic ignition incident after an explosion. This interview is the first in a two-part series on the subject.
Eyal is a graduate in Physics at Tel Aviv University and Electrical Engineering at Tel Aviv College. For years, he managed the ESD (Electrostatic Discharge Laboratory) at the Israel MOD Armament Development Authority. Since the 1980e, he has served as a consultant in the investigation of electrostatic discharge failure modes and the hazards associated with those discharges.
On July 7, 2021, an explosion occurred at a polyethylene pellet silo in Taiwan. It raised a lot of questions, especially since one gentleman responded to our post on the incident by saying that as far as he knew, all equipment was grounded, including the silos, bag filters, and ducting. He wondered how electrostatic discharge could occur in this fully grounded equipment.
This incident and the resulting commentary raised questions about how one goes about determining an ignition source and identifying it as electrostatic or not. Eyal answers many of these questions in this interview.
Determining Ignition Sources Can Be Challenging
Eyal explained that when he investigates explosion sites, he takes an approach consisting of several steps. Five of them focus on the specific ignition sources at the site.
“I call the first step ‘learning and acquaintance with the facility,’” he says. He reviews design documents and scans PMID systems, work procedures, and processing material documents to familiarize himself with all process conditions.
His next step is to collect information about processing material properties by reviewing plant documents, technical literature, and even laboratory tests like electrical volume resistivity, explosion limits. minimum ignition energy and temperature and flashpoint
Step three is a review of facility management and any history of failures. Eyal collects this information by checking the investigation report, summaries, and worker interviews before proceeding to step four, which is a visit of the affected area and review of data like photos, and step five, which consists of witness interviews.
“The sixth step is checking the data recorded in the facility at the time of the event,” he says. The goal is to identify the different parameters in place at the time of the explosion, such as failures, chemical materials [and] estimating consequences on the process itself.”
Step seven is a comparative analysis of the original process plan against the event version supplied by witnesses. Eyal identifies the equipment where the event began, looks for signs of soot, heat, rust, distortion, and even missing parts, and makes conclusions about what type of event occurred (fire, explosion or detonation).
“I [then] go to analyze if there was a possibility of static electricity being involved,” Eyal explains. “I analyze the electrostatic forces that took place in the specific equipment. It means identifying the conditions for the accumulation of electrostatic charges in the process, forming electrostatic calculations and the estimation of the electrostatic charge density and the electrical potentials that we accumulated in the materials and equipment parts.”
Conclusion
Eyal emphasized the importance of analyzing data as well as talking to witnesses.
“[I believe] everyone is telling the truth,” he says. “But memories can be different. Two people looking at the facility from different angles might say ‘No, it was an explosion’ and ‘No, there was black smoke first.’ Their evidence is very different.
By examining the scene and reviewing key documents and data, investigators can obtain the thorough overview needed to determine whether an electrostatic incident occurred and, if so, that is likely to have caused it. This is all information that can prevent similar events in the future and improve workplace safety everywhere.
If you would like to discuss further, leave your thoughts in the comments section below. You can also reach Eyal Zadok directly:
Email: [email protected]
LinkedIn: https://www.linkedin.com/in/eyal-zadok-975717174/
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
Dust Safety Science
Combustible Dust Incident Database
Dust Safety Science Podcast
Questions from the Community
Dust Safety Academy
Dust Safety Professionals
Incidents
Static Electricity May Have Caused Explosion at Taiwan Plastics Plant
Thanks for Listening!
To share your thoughts:
- Leave a note in the comment section below
- Ask a question to be answered on the show
- Share this episode on LinkedIn, Twitter or Facebook
To help out the show:
- Subscribe to the podcast on iTunes
- Leave a review and rate our show in iTunes to help the podcast reach more people
