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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 feedback@thehazmatguys.com or leave a message on our Haz Mat Guys comment hotline: 843-628-1484