Differences in Primary and Secondary FR Clothing

Primary FR workwear is an important PPE need in many industries – especially oil & gas. Selection and performance are guided by safety standards. However, whilst useful, a limitation of many PPE standards is that they deal with hazards in isolation, whereas in the real-world, safety managers must protect against multiple hazards at the same time. The danger is that one type of PPE can adversely affect the performance of another – and without users realizing. A case in point is when flame, heat or flash fire protection and chemical protection are required concurrently, a situation found commonly on refining and petrochemical sites, and where inappropriate combinations of PPE could prove fatal.


Industrial factory with global map

You can also download our whitepaper covering a detailed comparison of North American and European FR protective clothing standards and tests, and how they are useful in selection of both primary & secondary FR Clothing.

A Hazardous Combination of Protective Clothing?

On petrochemical sites especially, but also in many other industrial environments, primary FR workwear, fireproof clothing made from flame resistant fabric to protect against the hazards of flames, heat, and especially flash fire, is a PPE staple. However, when chemical protection is required at the same time, a common response is to simply wear what is assumed to be appropriate chemical protective clothing over the primary FR workwear. It seems an obvious and simple solution. And yet it creates a genuine and sometimes unrecognized hazard.

A second reason users might wear a standard disposable coverall over their primary FR garment is simply to keep it clean. Industrial environments are often dirty, and typical primary FR workwear can be expensive, with laundering both costly and detrimental to FR properties. A disposable coverall worn over it therefor can keep it clean, prolong its life, and reduce costs. Unfortunately, the same risk applies.

Why Can Layering PPE Be a Hazard?

Most standard disposable or chemical suits are made using hydrocarbon-based polymers. In other words, they are plastic, and in contact with flames are likely to ignite and continue to burn, even after the ignition source is withdrawn. They will then drip molten, burning plastic onto the FR garment, where it sticks and continues to transfer heat energy through to the wearers’ skin.

The consequence for the wearer can be catastrophic, with the thermal protection provided by the primary FR garment severely degraded, perhaps fatally. The solution is provided by correctly selected secondary FR Workwear.

The Purpose of Secondary FR Clothing

So, how is secondary FR clothing different to primary?

petrochemical worker donning secondary FR garmentThe clue is in the name. The primary purpose of Secondary FR clothing is not to protect against heat and flame. In fact, it is vital to understand that it should not be worn next to the skin at all because it is not designed to protect and is unlikely to protect against thermal hazards any more than any other clothing. Rather, it’s primary purpose is to provide protection against hazards other than heat, but without compromising the thermal protection offered by the primary FR clothing over which it is worn. In most cases its purpose is to provide protection against hazardous chemicals in dust or liquid form (in Europe clothing certified to chemical protection Types 3, 4, 5 or 6, or in North America, garments as defined by OSHA Level 3 PPE).

In short, then: –

  • Primary FR Workwear is worn in any application where there is a risk of contact with flames and heat or flash fire. It is designed to prevent or slow the transfer of heat energy from the source to the wearers’ skin and thereby to minimise burn injury. It provides the primary flame and heat protection.
  • Secondary FR Workwear provides little or no protection against flames and heat. Rather, it is worn primarily to provide protection against other hazards, such as chemical, but features essential FR properties so that it will not ignite and burn. This means it can be safely worn over the primary FR workwear without compromising flame and heat protection (unlike non-secondary FR clothing).

Secondary FR workwear therefor solves the problem, allowing users to safely combine PPE for two different types of hazard protection, flash fire and chemical, without dangerously compromising thermal protection, and ideally, enhancing it.

The essential flame-resistant properties of primary and secondary FR workwear and relevant standards are shown in the table below: –

FR tables for blog 1_96dpi

It is vital to understand that standard disposable coveralls or chemical suits must not be worn over clothing designed to protect against flames and heat (NFPA 2113 is very clear on this). The result could be severely reduced thermal protection. Any clothing worn over primary FR workwear must be classed as secondary FR workwear or flame resistant and should be certified either in Europe to EN 14116, or in North America it must meet the requirements outlined in NFPA 2113.

While this standard (NFPA 2113) contains no specific testing, it does require that any overgarments must be “flame resistant”. However, a more recent US standard does address the issue of testing of secondary FR workwear; ANSI 203(2018). This uses thermal mannequin testing to prove that overgarments do not constitute a hazard in terms of adversely affecting the thermal protection offered by the Primary FR Workwear.

What proof is there that standard disposables and chemical suits cannot be worn over Primary FR Workwear?

This is not just theoretical. It can be proved. Whilst primary and secondary FR clothing are assessed and certified according to standards in North America and Europe (you can read a detailed comparison of these in our downloadable whitepaper), for secondary FR garments, a limitation is that no standard requires testing in the way that they are used in the real world – worn over primary FR workwear.

However, thermal mannequin testing used for primary FR workwear, in which a test garment is subjected to a simulated flash fire whilst worn on a thermal mannequin, is the only effective way to show the consequence of wearing different coverall types over primary FR clothing. The test produces a body map of predicted body burn showing both 2nd and 3rd degree types, so is a useful assessment of comparative performance and is ideal for proving or disproving effectiveness of any garment worn over primary FR workwear.

Being the only available method, Lakeland have conducted testing on different FR clothing combinations. The results of the tests to show the effect of non-secondary FR clothing are shown below: –

two body burn maps










The difference is dramatic. The non-FR rated disposable garment worn over the primary FR garment results in an increase in predicted body burn from 37% to 53% – an increase of 43%. This could easily mean the difference between life and death.

The new US standard ANSI 203(2018) uses the same method of layered mannequin testing

In fact the new US ANSI 203 standard uses the same method for testing of Secondary FR Workwear overgarments. It requires that any garment intended to be worn over primary FR workwear must undergo thermal mannequin testing as follows: –

  1. A thermal mannequin test is conducted on a sample of Primary FR workwear in order to identify base predicted Body Burn
  2. The SFR workwear is then tested (in the same test period) whilst worn over the same primary FR garment in order to identify the effect on predicted body burn compared with the first test.

The performance requirement of the standard is that the layered configuration shall: –

  1. Not result in predicted body burn of more than 50% (the same requirement is in the NFPA 2112 thermal mannequin test for Primary FR Workwear)
  2. Not result in a greater than 2% increase in the predicted body burn shown by the primary FR garment alone

In other words, this new standard provides an ideal method to ensure that any garment you intend to wear over a primary FR coverall does not result in a degradation of thermal protection.

The solution is provided by properly rated secondary FR workwear. Garments that will both provide the chemical protection required but can be safely worn OVER primary FR workwear without compromising thermal protection. Garments such as Pyrolon®, Lakeland’s unique range of secondary FR workwear that provides a range of chemical protection from hazardous dusts and low hazard to high hazard liquid chemicals, and yet have excellent flame-resistant properties and fully meet the requirements of both US and EN standards.

Detail Matters!

Download our free whitepaper covering: –

  • The difference between Primary & Secondary Workwear
  • Detailed review and comparison of both European EN and US NFPA FR standards for primary and secondary FR clothing
  • How the tests used in each can be used to get the best from your FR clothing selection.
  • Which tests in the standards provide effective performance assessment of both primary and secondary FR clothing
  • How the new ANSI 203 standard is perfect for testing secondary FR workwear to ensure it does not constitute a hazards
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