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Last week, while witnessing a drill at a chemical industry, the emergency scenario involved a toxic gas release. The response team quickly wore their hazchem suits, but to my surprise, the suits were not designed for gas emergencies. During the debrief, when this point was raised, the reply was: “We have only this type of suit, and we have been using it since the company began operations.”
This incident highlighted a common yet critical gap in industrial safety: a lack of understanding about the types of protective suits, their limitations, and their correct application. Fire teams, emergency responders, and safety departments must go beyond simply owning hazchem suits. They must know the classification, level of protection, limitations, and maintenance of these suits.
When it comes to chemical protective suits, two terms are often misunderstood:
Penetration – The bulk flow of chemicals through zippers, seams, closures, or imperfections in the fabric. For example, a liquid dripping through an unsealed zipper.
Permeation – The process by which chemicals pass through the suit material at a molecular level, even if there is no visible leakage. This is a time-dependent process and critical for gases and vapors.
Both factors determine how effective a suit is in real emergencies. A suit that protects against liquid splashes may still allow vapors to permeate over time, making it unsuitable for gas releases.
Different international standards classify suits based on protection levels. The most commonly referenced are NFPA (National Fire Protection Association, USA) and EN (European Norms).
NFPA 1991 – Vapor-protective suits (Level A). Fully encapsulating, gas-tight suits providing maximum protection against toxic gases, vapors, and liquids.
NFPA 1992 – Liquid splash-protective suits (similar to Level B). Not vapor-tight but resistant to liquid chemicals.
NFPA 1993 – Protection against liquid chemicals under pressure (spray applications).
NFPA 1994 – Protective ensembles for chemical/biological terrorism incidents, various classes depending on vapor or liquid threats.
Chemical protective suits are categorized as Types 1 to 6:
Type 1 – Gas-tight (equivalent to NFPA Level A). Maximum protection against gases and vapors.
Type 2 – Non-gas-tight, positive pressure suits.
Type 3 – Liquid-tight, protecting against strong jets of liquid chemicals.
Type 4 – Spray-tight, protecting against liquid sprays.
Type 5 – Suits for solid airborne particles (dust protection).
Type 6 – Limited protection against light sprays and splashes.
Gas Releases – Require fully encapsulating, gas-tight suits (NFPA 1991 / EN Type 1). Anything less leaves responders vulnerable to permeation.
Liquid Splashes or Jet Releases – Level B (NFPA 1992 / EN Type 3 or 4) is sufficient, provided respiratory protection is used.
Dust Hazards – Type 5 suits protect against airborne particulates, often used in pharmaceutical or powder-handling industries.
Minimal Risks – Type 6 suits, for very low-level exposure where only splash protection is needed.
Protective suits are not “one-size-fits-all” and their effectiveness decreases without proper care:
Cleaning & Decontamination – Suits must be cleaned following manufacturer guidelines to prevent chemical residue buildup.
Inspection – Regular checks for seam integrity, zipper function, and visor clarity are essential.
Service Life – Chemical suits degrade over time. Using expired or damaged suits in emergencies compromises safety.
Limitations – No suit is 100% resistant to all chemicals. Permeation tables provided by manufacturers should always be reviewed for the specific hazard.
The incident I witnessed is a reminder that owning hazchem suits is not enough—understanding their classification, protection level, and limitations is critical. Safety leaders must ensure that the right suit is available for the right hazard, and that responders are trained in both selection and use.
When it comes to chemical emergencies, the difference between penetration and permeation, or between a dust suit and a gas-tight suit, can be the difference between life and death.
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