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THMG008 – Oxidizers

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In this episode, Mike and Bob discuss oxidizers are and how we interact with them.

Complete Show Notes

4:40 What is An Oxidizer?

  • Part of a system known as a redox reaction or a reduction-oxidation reaction
  • Specifically deals with the loss or gain or electrons – oxidizers are stronger than most other chemicals, so they just take what they want
  • Elements are always trying to reach a neutral state, so when oxidizers take a chemical’s electrons, the chemical is no longer in a balanced, happy state
  • Oxidizers either break the chemical apart or start to react with another chemical that it can get an electron from or give an electron to

7:35 NFPA Definition of Oxidizers

  • “Any material that readily yields oxygen, or another oxidizing gas, or that readily reacts to promote or initiate combustion of combustible materials and can undergo a vigorous, self-sustained decomposition due to contamination or heat exposure”

8:05 “Any material that readily yields oxygen, or another oxidizing gas…”

  • Many oxidizers contain oxygen and release that oxygen into the system when they react
  • This can present the danger of oxygen enrichment and can change our LEL and UEL levels
  • Also accelerates chemical reactions, which can be very dangerous
  • Airborne oxidizers are difficult to control and can lead to unexpected reactions in other locations

10:05 “Or that readily reacts to promote or initiate combustion of combustible materials…”

  • If enough heat is generated and oxygen becomes part of the reaction, we get fire
  • This is one of the biggest dangers of an oxidizer – they have the potential to catch us off guard
  • It can take a while to build up heat – from minutes to hours

12:45 “And can undergo a vigorous, self-sustained decomposition due to contamination or heat exposure.”

  • This means the oxidizer can produce enough heat to break itself down
  • Contaminants can be organic combustibles, which react to build heat and start a chain reaction
  • Oxidizers are also light- and heat-sensitive and can be broken down by these factors

15:00 Where Can We Find Oxidizers?

  • Anywhere – we all use oxidizers on a regular basis
  • Residential settings – kitchen and bathroom – hydrogen peroxide, toothpaste, etc.
  • Industrial settings – rocket fuel, stump removers, gunpowder, preservatives, etc.
  • On the road – transported via DOT Classification 5 over the road trucks as a liquid or solid

17:25 How Do We Recognize an Oxidizer?

  • Placards
  • Labels
  • From the chemical name – If it ends with “-ate,” “-ite,” or “-ide,” it’s more than likely an oxidizer
  • Non-organic halogenated compounds
    • Non-organic substances don’t contain carbon
    • Halogenated compounds contain fluorine, bromine, chlorine, or iodine
    • If you’re dealing with any of these substances, they’re oxidizers
  • Treat the following as oxidizers: nitrites, nitrates, and peroxides

21:55 National Fire Protection Association (NFPA) Oxidizer Classifications

  • Classes 1-4: the higher the number, the stronger the oxidizer and the greater likelihood of a reaction
  • Class 1: No measureable increase in the burning rate of combustible materials it comes into contact with
  • Class 2: Moderate increase in the burning rate of combustible materials it comes into contact with
  • Class 3: Can undergo an explosive reaction due to the contamination or exposure to thermal or physical shock, severely increasing the burning rate of combustible materials it comes into contact with
  • Class 4: Can undergo an explosive reaction due to contamination or exposure to thermal or physical shock, causing a severe increase in the burning rate of combustible materials it comes into contact with

23:50 Case Study: Texas City Disaster

  • Texas City cargo ship caught fire in 1947 – responders originally thought it was a grain fire, so they tried to smother the fire when water didn’t work
  • Ship detonated – took out the entire fire department, knocked a plane out of the air, and leveled half of the town
  • Actual cargo was ammonium nitrate fertilizer, which is an oxidizer

26:30 Things to Consider

  • Always identify the specific oxidizer you’re dealing with
  • Recognize the possibility of a reaction or explosive hazard
  • Evaluate the density of the material – the higher the density, the greater the risk of explosion
  • Consider how much contamination got into the product that’s burning
  • Think about the particle sizes – the smaller the particle, the greater the hazard
  • Use copious amounts of water to cool off the material and halt the decomposition – keep runoff in mind, though

28:15 Extinguishing Fires

  • Extinguishing agent you use can react with the oxidizer that’s present
  • Dry Chem makes the fire worse – you can create an explosive byproduct
  • O2 displacing agents also can’t be used because they create their own oxygen source and will continue to burn
  • If you have a large fire, consider whether you’re in an indoor or outdoor environment – evacuate the area and allow a free burn
  • Set up large caliber streams to throw large quantities of water over a long distance
  • Remember that smoke is highly toxic, so use SCBA and set up your zones

29:40 Handling Spills

  • What did the substance come into contact with? Did it mingle with things it doesn’t play nicely with?
  • How strong is the oxidizer?
  • Is the substance reacting? It might be giving off heat, releasing vapors, bursting into flames, etc.
  • Will it react with metal?
  • Are there contaminants in the over pack container? Consider flooding the over pack with water.

Have a question? Send an email to feedback@thehazmatguys.com or leave a message on our Haz Mat Guys comment hotline: 843-628-1484

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