It is vital that any professional who puts his or her life on the line to deal with dangerous situations is well prepared. With this in mind, Ian Hutcheson of Saint-Gobain Performance Plastics, provides a better understanding of EN and NFPA standards for chemical protective suits

The correct level of training is obviously an integral factor when it comes to working in dangerous environments. However, when a hazmat suit is the only thing standing between a first responder and harmful chemicals or gases, it is clear that the performance of the suit is just as important. As such, these suits must adhere to certain standards, which can differ depending on where they are sold.

Certification overview

Throughout Europe, the certification standards are defined and maintained by the European Committee for Standardisation (CEN). The highly respected EN 943 standard covers protective clothing against liquid and gaseous chemicals with a specific section – EN 943-2 – dealing with chemical protective suits for emergency responders and firefighters.

The leading advocate for fire prevention and public safety in the US and Canada is the National Association of Fire Protection (NFPA).  NFPA 1991 certification sets standards for chemical permeation, vapour tightness, flame resistance and material durability, with an optional criteria for chemical flash fire escape and liquefied gas protection.

When comparing the two certifications, it is important to understand the different test methodologies and minimum performance requirements to ensure a suit provides the maximum protection. Detailed here is the comparison of the test requirements results in five key areas of performance evaluation.

Chemical permeation testing

For chemical permeation testing, both EN 943 and NFPA 1991 use the same test methodology. However, EN 943 has a less severe minimum permeation detection level of 1.0mg/cm2/min versus the NFPA 1991 level of 0.1mg/cm2/min.

In addition, NFPA 1991 requires pre-conditioning prior to chemical permeation testing, while EN 943 testing does not. This means that NFPA 1991 certified materials are subjected to the physical stresses of both flexing and abrasion of the outer surface with course sandpaper repeatedly before actual permeation testing. Some high performance protective suits are NFPA 1991 certified, having been put through this rigorous abrasion pre-conditioning before chemical permeation testing, but other suits rely on an aluminium oversuit or cover to meet this requirement.

Gases and chemical warfare

NFPA 1991 chemical testing covers a much broader spectrum of chemicals than EN 943. It covers all the chemicals listed in EN 943 except for heptane and additionally specifies only one-tenth chemical permeation detection level requirements.

Pressure testing

Both tests involve the suit being pre-inflated at an elevated pressure and while this is only one minute for NFPA, it is ten minutes under the EN standard. More importantly though, EN 943 features an actual six minute test period at 1,650Pa (6.6” water pressure), while the NFPA 1991 test is only for four minutes duration at 1,000Pa (4” water pressure). However, both standards are similar in not allowing any more than 20% loss of starting pressure over the test period – although actual results on suits in use should be well above these thresholds for maximum reliability.

Flame and flash resistance

There is no inclusion of test for flash fire resistance in EN 943 certification and it requires very limited flame resistance (one second), whereas  NFPA 1991 certification involves more rigorous flame and burn testing and has the optional test of flash fire resistance. For example, for flame resistance testing, the NFPA 1991 certified ONESuit Pro protective suit has undergone two exposures – one touching a flame source for three seconds (with no ignition allowed) and another 12 second exposure with no burning after ten seconds and no melt or dripping. Interestingly some suits that meet the requirements of EN 943-2 do not meet the NFPA 1991 standard unless they are equipped with a second aluminised oversuit which significantly reduces comfort and dexterity and increases weight and bulk.

Flash fire resistance is an optional requirement met by suits such as the ONESuit Flash. The test method includes putting the ensemble onto a mannequin in a sealed, propane filled flash chamber. The suit is then subjected to a remotely ignited six to eight second burn and must exhibit airtight integrity, thermal insulation and visual acuity following the exposure to meet minimum standards – all in addition to the requirement for no after flame.

Hand protection

In terms of protective suit accessories, both NFPA 1991 and EN 943-2 certifications require gloves to meet a high level of chemical and permeation resistance. NFPA 1991 has set much higher standards for cut and puncture resistance, which require that an outer glove be worn in addition to the chemical barrier glove. In most cases, two barrier gloves (a film inner and elastomer outer glove), are worn to obtain the full range of chemical protection and breakthrough times. However, there are solutions that are able to offer this puncture resistance and chemical permeation resistance in a single piece construction.


There are clearly key differences between EN 943 and NFPA 1991 that need to be understood. However, in order to ensure maximum protection, organisations should specify suits that meet both EN 943 and NFPA 1991, and certification requirements.


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