Chemical suits are your first line of resistance against extreme chemical hazards.  Choosing the right suit is imperative to protect your workers.  With so many options and different fabric technologies; choosing the right suit can sometimes be confusing.  After reviewing some of the most popular suits on the market right now, such as the Tyvek® coverall, we discovered there are some key criteria you should be considering when choosing a chemical suit or coverall.

Chemical Suite
Dupont Tyvek Chemical Suit

In order to know what suit you should be wearing and when, you first have to know what the options are.

Levels of PPE

Personal protective equipment (PPE) is divided into four categories based on the degree of protection afforded:

  • Level A protection should be worn when the highest level of respiratory, skin, eye and mucous membrane protection is needed. A typical Level A ensemble includes:
    • Positive pressure (pressure demand), self-contained breathing apparatus (SCBA) (NIOSH approved), or positive-pressure supplied air respirator with escape SCBA.
    • Fully encapsulating chemical protective suit.
    • Gloves, inner, chemical resistant.
    • Gloves, outer, chemical resistant.
    • Boots, chemical-resistant, steel toe and shank; (depending on suit boot construction, worn over or under suit boot.)
  • Level B protection should be selected when the highest level of respiratory protection is needed, but a lesser level of skin and eye protection is needed. Level B protection is the minimum level recommended on initial site entries until the hazards have been further identified and defined by monitoring, sampling, and other reliable methods of analysis, and equipment corresponding with those findings utilized. A typical Level B ensemble includes:
    • Positive-pressure (pressure-demand), self-contained breathing apparatus (NIOSH approved), or positive-pressure supplied air respirator with escape SCBA.
    • Chemical resistant clothing (overalls and long-sleeved jacket, coveralls, hooded two-piece chemical splash suit, disposable chemical resistant coveralls.)
    • Gloves, outer, chemical resistant.
    • Gloves, inner, chemical resistant.
    • Boots, outer, chemical resistant, steel toe and shank.
  • Level C protection should be selected when the type of airborne substance is known, concentration measured, criteria for using air-purifying respirators met, and skin and eye exposure is unlikely. Periodic monitoring of the air must be performed. A typical Level C ensemble includes:
    • Full-face or half-mask, air-purifying respirator (NIOSH approved).
    • Chemical resistant clothing (one piece coverall, hooded two piece chemical splash suit, chemical resistant hood and apron, disposable chemical resistant coveralls.)
    • Gloves, outer, chemical resistant.
    • Gloves, inner, chemical resistant.
    • Boots, steel toe and shank, chemical resistant.
  • Level D protection is primarily a work uniform and is used for nuisance contamination only. It requires only coveralls and safety shoes/boots. Other PPE is based upon the situation (types of gloves, etc.). It should not be worn on any site where respiratory or skin hazards exist. Along with keeping potential contaminants OUT….this suit is also very useful to keep potential contamination IN such as in the case of crime scenes being examined by police forensic investigators, fire scenes being investigated by fire investigator, etc.

The information above should serve as a guiding starting point, but it’s important to remember that every particular situation will vary.  There are three other elements to consider when choosing the correct level of protection:

  1. Permeation or penetration
  2. Type of exposure
  3. Seam type

Permeation vs Penetration:

The first step is to determine which fabric material you should be using to protect against the expected chemical hazard. To do this, you will want to take the list of chemicals that you may come in contact with and compare them with some sort of chemical testing that was performed by the manufacturer. When testing, the higher the score or longer the time for penetration/permeation, the better the suit will protect you from a chemical.

Permeation testing measures the amount of chemical product that gets absorbed or diffuses through the actual suit material. This test assesses how well the chemical suit material can keep chemical molecules from passing through the solid suit material itself. Think of osmosis from high school chemistry, how water can pass through a membrane.

Penetration on the other hand measures how much chemical product is on the inside of the suit material … essentially measuring how much chemical passes through a pore, stitch, or some sort of opening/passageway in the suit material. This is testing a passage many molecules through the suit. Think of a dam cracking and bursting through.

Permeation is the more common (and rigorous) test that you will see.  It gives a better indication of how long it takes before the suit material itself is going to be comprised before it actually fails so we recommend using this test data to make your decision whenever possible.

Type of Exposure:

Determine what type of exposure you have:

  • Prolonged? Spray? Etc. Different suits and meant for different exposures.

Gather a list of chemicals you may be in contact with:

  • An SDS is your best bet and will often even give recommendations for clothing.
chemical suit seam type
4 types of seams for chemical suits

There are 4 main types of seams on chemical suits:
1. Serged or Stitched Seam: joins two pieces of material with a thread stitch that interlocks. This is economical and generally not used for chemical protective clothing. It is more commonly found on limited use clothing where dry particulates are of a concern.
2. Bound Seam: joins two pieces of material with an overlay of similar material and is chain stitched through all of the layers for a clean finished edge. This provides increased holdout of liquids and dry particulates.
3. Heat Sealed/Taped Seam: seams are sewn and then sealed with a heat activated tape or can also be ultrasonically welded. This method provides liquid proof seams, and is especially useful for Level A and B chemical protective clothing as there are no holes in the suit for chemical penetration.
4. Heat Sealed plus Double Taped: the strongest seam. The seam is sewn and then heat sealed on the outside and inside to offer the highest strength and chemical resistance. This is the highest level of protection that you can get as it is double the protection against chemical penetration.

When choosing the right seam, consider the likelihood of a splash and the severity of the chemical product you will come in contact with. i.e. large dry particles are good with stitched seams while hazmat response or chemicals spray under pressure applications are better suited for double taped seams.

You should have a pretty good idea at this point of the suit you should be wearing.  The final thing to look at is the suit construction type; does it have booties? Elastic cuffs? Hooded?  This decision can largely be a personal preference but be sure that the suit offers adequate protection against the job you are doing.

That’s it! You should now know exactly what type of suit you should be wearing to protect against your chemical risks, but in case you’re still a bit confused, give us a call (1-888-453-8488) and a safety specialist would be happy to discuss your chemical risks and help you pick the correct chemical suit.

Also don’t forget, now that you have the proper suit, be sure to treat it properly! Check manufacturer instructions for proper suit inspections to ensure optimal performance and longevity. More on this topic to come!

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Eric Huard

Market Segment Manager, Personal Safety

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