Home Interviews THMG148 – Hydrofluoric Acid Series, Part II: Interview with Stephen McManus

THMG148 – Hydrofluoric Acid Series, Part II: Interview with Stephen McManus


In this episode, Mike talks to Stephen McManus about a few of the more memorable hydrofluoric acid incidents he’s been involved with.

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Complete Show Notes

3:10 Introduction to Stephen McManus

  • Career firefighter who also did a stint in the industrial side as a career chief for an industrial fire department
  • Also worked as a volunteer firefighter over the years

3:40 Working on a High-Hazard Team

  • Worked on a high-hazard team in the 90s that traveled around the world working for different governments
  • In one case, they were working in a facility that had been abandoned for 20 years – contained a 55-gallon drum of hydrofluoric acid
  • Room also contained uranium hexafluoride and a number of other different chemicals – this potentially-enriched uranium added another twist and added the potential for an explosion
  • Room was only 5 x 5 or 5 x 8 – drum was so rusted and damaged that they were worried about a rupture
  • Posed a criticality issue – this facility had been involved with weapons, and the enriched uranium made things even more dangerous
  • Bladder was holding everything inside the drum – everything else was so rusted you could have stuck a pencil through it
  • Took a lot of different people from various backgrounds to design a plan to safely go in and do the necessary work
  • Team worked in Level A suits and used peristaltic pumps to transfer the acid safely into another tank in the same room
    • Peristaltic pumps allow you to create a suction without running the product through the pump itself
    • Uses compressed tubing that goes around the pumping mechanism
    • Tubing is disposed of afterwards since it’s contaminated and basically destroyed
  • A pinhole formed on the tubing as they were making the transfer, which allowed hydrofluoric acid to escape into the room – luckily, they were prepared for almost any kind of leak
  • Vapors from escaped hydrofluoric acid started to eat camera lens in the camera used by one of the agencies watching the high hazard team
  • Went through a whopping 12 Level A suits during the 3 days of working on the operation – were able to deal with everything in the room, though
  • Level A suits were the main limiting issues for the team, but they chose this level of protection due to their work-ups and the safety information they’d gathered
  • Did wet decon with a few chemical mixtures based on the potential of not having any contamination due to coming into contact with hydrofluoric acid – were more concerned with getting the person out than saving the suit

21:15 Dealing with Buried Cylinders

  • Had to deal with hundreds of stacked cylinders that contained a wide variety of mixed gasses – specially designed with valving on both ends
  • None of these chemicals should have been mixed together – dealing with them was very dangerous for the team
  • Had to drill into the cylinder, remove the product, and run it through a scrubber system
  • One of the cylinders contained hydrofluoric acid mixed with another dangerous gas – ended up reacting with the scrubbing unit
  • Scrubber started to dance around on the floor even though it weighed 400-500 pounds – also spewed black liquid from one of the charcoal systems
  • Had to deal with shutting the scrubbers down while also handling the product in the scrubbers and continuing to contain the hydrofluoric acid
  • Luckily, it was a smaller cylinder, so there wasn’t as much product to deal with
  • Used a collar system that could be fitted onto any cylinder and helped create a valve as you drilled into the cylinder
  • Existing valving was bad on the cylinder itself, so the collar system formed a vacuum around the bad valving – this became the valve that you could pull product through
  • Wore Level A protection since there were toxicity concerns along with fire and explosion potential

32:30 Assessing Hydrofluoric Acid Cylinders

  • Handle this essentially the same way you’d analyze and assess any cylinder
  • Analyze the integrity of the body – how much damage has been done by rust or otherwise?
  • Has it been physically damaged? Are there any gouges or cuts?
  • Does the valving and threading appear to have leaked at any time?
  • Is the metal of the valving still intact? Are there any stress fractures?
  • Has it been subjected to any thermal damage (i.e. fire)?
  • Has it leaked?
  • Use pH wipes on the outside to determine whether there’s any type of reaction with the metal

34:05 Dealing with Leaking Pipes

  • In one case, leaky pipes were spraying hydrofluoric acid across a staircase they needed to use to get to an area where they could mitigate the problem
  • Had to devise a shield system to keep the pinstream leak of hydrofluoric acid from getting onto the responders
  • Team was able to close a valve off to stop the actual leak in the pipe – had to catch runoff from the pipe while also dealing with vaporized hydrofluoric acid
  • Stephen’s team stopped the leak, offloaded the leaking tank, and vented the room
  • Another team came in to do the final cleaning and neutralize the hydrofluoric acid that had gotten into the concrete – room was condemned and wouldn’t be used again

41:00 Stephen’s Biggest Tips for Responding to Hydrofluoric Acid Incidents

  • Always know your risk and make sure you’re dealing with the product you think you are
  • Stay alert of what other substances are in the area
  • Assess how bad the leak is – applies for both liquid and gaseous hydrofluoric acid
  • If you’re dealing with a gas leak, know what’s in any nearby containers – you could be dealing with a potential reaction
  • Know whether there’s potential for a catastrophic failure for the vessel you’re dealing with and/or if the leak could cause catastrophic failure to another vessel
  • Think about how far your recon team is going to explore – how big is your scene survey?
  • Make sure local hospitals and on-site medical staff are prepared to deal with hydrofluoric acid exposure

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