The HazMat Guys

In this extra episode, we chat with DuPont resident expert Dan Bowen. We discuss how DuPont chemical protective suits are tested, which standards they’re tested to, and why. Take a listen to this is a very informative episode on PPE.

Complete Show Notes

0:45 Introduction to Dan Bowen

  • Technical specialist for DuPont Protection Technologies – supports end users of their protective apparel products
  • Works with both industrial users and first responders for every type of suit they make
  • He covers all of North America and is basically the field geek for supporting the product lines

2:15 How Are DuPont’s Garments Chemically Tested?

  • They use actual chemical testing to evaluate the performance of the materials
  • Penetration testing
    • Visual only test that works well for closures, seams, and zippers
    • Helps you determine whether the suit can keep out dirty water
    • Challenge material is put in contact with the suit and lab technicians then take a look at the other side of the suit to see if the material is coming through
    • Problematic because you can’t see vapors coming through or trace amounts of dangerous liquids
  • Permeation testing
    • Put a challenge material in contact with material in question, and some sort of monitor is put on the other side – much more scientific
  • DuPont doesn’t do their own testing – instead, they use independent third-party laboratories
  • Testing procedure
    • Start a stopwatch as soon as the chemical comes into contact with the material
    • Report the number of minutes it takes for the chemical to be sensed as it comes through the material at a tenth of a microgram per square centimeter
    • As soon as they hit that threshold, the stopwatch is stopped
    • They report the number of minutes it took that chemical to come through that particular fabric at that concentration
    • Testing is stopped at 8 hours
  • DuPont has their own permeation database – symbols include:
    • IMM (immediate) – any permeation less than 10 minutes
    • Number between IMM and 480 minutes – they’ll report the actual number of minutes
    • Greater than 480 minutes – means the chemical didn’t come through the fabric within 8 hours

7:00 How Does DuPont Decide Which Chemicals to Test?

  • Chemical Abstract Library (CAL) lists over 100 million chemicals
  • Each chemical test runs from hundreds to thousands of dollars, so they can’t test everything
  • DuPont’s permeation database contains test data for the most common chemicals we come into contact with – sulfuric acid, nitric acid, phosphoric acid, ammonium, etc.
  • Database may not have the exact chemical you’re looking for, but chances are it has permeation data on a substance that’s pretty close to the one you’re dealing with – i.e. hexane and oxygen
  • It’s important to have information on the class and subclass of the substance you’re handling when you go to use the database

10:50 How Do They Determine When a Chemical is Too Strong for the Suit?

  • In the U.S., the tenth of one microgram per square centimeter figure from before is what’s reported
  • In Europe, it’s one microgram per square centimeter
  • Make sure you’re looking at the right permeation data to ensure you’re comparing apples to apples

12:10 How Do Concentration and Temperature Affect Suit Permeation?

  • They may have data for a range of concentrations in the permeation database for both liquids and vapors
  • Phase changes have to be taken into account since substances are most concentrated when they’re liquids because their molecules are closer together
  • You also have to think about working strengths of chemicals – database also has information for these since people may buy full-strength chemicals and then dilute them
  • If you have a concentration that’s lower than the concentration in the database, you can trust the database – if it’s higher, you can’t trust the database
  • For every 10 degrees Celsius the temperature increases, permeation time is essentially cut in half
  • Database also includes a range of temperatures they’ve tested certain chemicals at
  • Remember that if a chemical gets hot enough, it can actually melt the surface of the suit (rather than permeating it)

20:25 Is it Safe to Reuse Suits?

  • DuPont uses MUSE (Multiple Use, Single Exposure) as a guideline – safe to reuse garments as long as they weren’t exposed to anything
  • Encapsulated Level A suits are extremely expensive ($1,500-$3,500), so a lot of people are tempted to reuse them
  • DuPont recommends against reusing Level A for several reasons
    • Decon isn’t designed to neutralize substances – it’s designed to make it safe for us to exit our suits
    • We have no guarantee that whatever we’re using to decon the suit can make it safely reusable
    • Permeation starts the minute the material comes into contact with the fabric – this means we have no way of knowing whether it can still perform as well when it did when it was brand new
    • Incompatibles are also an issue – this can be problematic if two incompatibles come into contact with one another on the suit
  • Don’t get rid of your Level A, though – you may be able to use it for training or other purposes depending on its condition
  • DuPont offers a lot of different training suits you can use

28:15 Ways to Demonstrate the Differences Between Penetration and Permeation

  • Oil of wintergreen in a plastic baggie or Ouzo liqueur and a butyl glove – two everyday examples
  • You won’t smell anything at first, but you will in a few minutes because the substances have permeated into the baggie and glove
  • Same thing goes for two-stroke engine mix – baggie doesn’t dissolve, but the material comes right through the walls very quickly
  • You can’t stop permeation, which is why DuPont recommends that you should never reuse a Level A

33:05 More Information

  • Contact Dan via email: Dan Bowen
  • Check out DuPont’s SafeSPEC® program – also available as an app for iPhone and Android
    • Includes permeation database
    • Lost of videos on how to don and doff
    • Whitepapers on a variety of topic
  • There’s a “Contact Us” form on the SafeSPEC® site
  • DuPont also provides a ton of free resources and sample suits
  • They also put out a quarterly newsletter called The Glow Worm for the hazmat community

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

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