…and what are the consequences for selection of flame and heat protective clothing?
When it comes to protection against real world hazards and selection of suitable PPE, safety managers developing an effective health and safety plan in some industries must juggle multiple hazards. In the petrochemical and oil & gas industries for example, commonly workers not only need to be protected against fire but also against harmful chemicals – and very often at the same time
However, it’s not as simple as putting chemical protective wear over FR workwear – standard chemical protective clothing is made using plastic based fabric that will ignite, burn and melt and so will compromise fire protection. As such, safety managers need to understand the differences between the two, what protection they offer, how they are tested and what types work together.
With this in mind this blog considers:-
- The uses of Primary and Secondary FR Workwear
- The key differences between them
- How they are certified and tested
- What those tests mean for selection of FR and chemical safety clothing where flame and chemical protection are required at the same time.
What are the Differences in the Level and Type of Protection Offered by Primary and Secondary FR workwear?
Primary FR Workwear
Primary FR workwear is designed to ensure protection against flames, heat and/or molten substance splashes. This type of workwear is typically worn by those in the petrochemical and oil & gas industries due to the ever-present risks of flash fire and the flammability of the chemicals they work with.
Primary FR Workwear is certified to standard EN 11612, and given the nature of petrochemical and oil & gas environments, protection against flames, heat and especially flash fires, is a basic requirement – and as such, Primary FR workwear must be worn in most operational areas of most plants.
However, petrochemical and oil & gas environments are also riddled with hazards other than flames and heat and safety managers also must address these and ensure workers are fully protected.
The most common hazard is probably that of hazardous toxic chemicals. There are thousands of chemicals in use throughout the world on a daily basis and different facilities may have anywhere between a handful and hundreds on site at any one time… many of which are extremely hazardous… possibly causing life-changing illnesses and in the worst cases even death.
Moreover, some chemicals – upon exposure – have no immediate or obvious effects, leaving workers to believe they are safe until the problems become apparent hours, days, months or years later.
Why is a Combination of Fire Protective Clothing and Standard Chemical Protective Clothing a Hazard?
Where both flame and chemical protection is required at the same time, it has become common to do the obvious… to wear a chemical suit over Primary FR workwear. The problem is this creates a new hazard because most chemical suits are constructed of polymers which are flammable – they will ignite, burn, drip molten debris and ultimately destroy the effectiveness of the primary FR Workwear beneath…
The Solution… Secondary FR workwear
On the other hand, secondary FR workwear is designed to provide chemical protection over Primary FR workwear without compromising thermal protection. In other words, it enables a safe combination of flame and chemical protection.
Secondary FR workwear is certified to EN 14116. This “lower level” FR standard, whilst having the slightly misleading title of “Protective Clothing – protection against flame, limited flame spread materials, material assembly and clothing” actually provides for basic FR testing to show not that the material will provide protection against flames and heat, but that it will not ignite and burn or drip… in other words that it will not propogate a flame and thus will not damage the FR protection offered by the EN 11612 garment worn beneath it.
The use of standard chemical safety clothing over primary FR workwear is less common than it was a decade ago; the fact that Secondary FR Workwear is required is now relatively well known. However a challenge remains in a lack of clear understanding of how the two different types of clothing – Primary and Secondary FR workwear – are tested and what those tests mean and tell you about protection performance. Without such an understanding, users can have little appreciation of how well Primary FR and Secondary FR workwear garments will work together.
The difference in standards and tests used to assess garment performance
As mentioned, Primary FR workwear is certified to EN 11612, whereas Secondary FR is certified to EN 14116 – but what does that mean? What tests are required by these standards?
Tests in EN 11612 for Primary FR workwear
EN 11612 specifies the performance requirements for garments made of flexible materials – which are designed to protect the wearer’s body from heat and/or flame.
This pictogram is required on garments certified to EN 11612 to indicate protection against flames and heat. It is NOT required for garments certified to EN 14116 – but is often used in any case.It is therefor vital to check certification where this pictogram appears; does it indicate certification to EN 11612 or EN 14116… one will protect against flames and heat… the other will not…
The standard contains a number of tests to assess the performance of the fabric:
Basic Heat Stability and Flammability
First, a heat stability test ensures the fabric will not shrink more than 5% at a temperature of 180C and an optional temperature of 260C, whilst a basic flammability test indicates that the fabric will not ignite and will not generate a hole (larger than 5mm) in contact with a flame.
Heat Energy Transfer Resistance Tests
Second, at least one of five heat energy transfer resistance tests must be conducted to measure the fabric’s effectiveness at resisting the transfer of heat energy from a heat source to the skin of the wearer. The results of each are classified according to performance (usually 1 to 3) and identified by a code letter as shown below:-
- Convective Heat: Code letter B – performance levels B1 to B3
- Radiant Heat: Code letter C – Performance levels C1 to C4
- Molten Aluminium Splash: Code letter D – Performance levels D1 to D3
- Molten Iron Splash: Code letter E – Performance levels E1 to E3
- Contact Heat: Code letter F – Performance levels F1 to F3
An important factor in the effectiveness of primary FR workwear is the layer of air held between the garment fabric and the wearers skin. Air is good insulation against heat energy transfer so the wider that layer is the better the overall protection.
Thus a fabric which immediately shrinks excessively when it comes into contact with heat will shrink onto the body, tightening the fit and reducing or removing that added insulation, resulting in less effective protection.
This is also why FR workwear is traditionally made to a larger sizing and can seem quite loose fitting. Loose fitting FR workwear is more effective FR workwear (provided it does not become a hazard in other ways by being too baggy).
The last thing you need when it comes to FR workwear is a tight fitting garment. It might look better… but it certainly won’t protect you better…
In general terms these heat resistance performance levels for each heat energy type can be applied to real world applications as follows:-
Application Risk Level
|Heat Energy Resistance Test Performance Level|
|Performance Level 1|
|Performance Level 2|
|Performance level 3|
|Performance Level 4
(Introduced for Radiant Heat Only to reflect high performance materials such as aluminised materials for high level radiant heat applications)
Given these tests measure resistance to transfer of different forms of heat energy they can be useful in ensuring a garment is suitable for an application where that type of heat energy is a hazard.
However, all of the heat energy resistance tests are conducted on the garment fabric – not on the finished, whole garment.
Whole Garment Tests
Finally, the standard includes a Thermal Mannequin Test, which subjects a finished garment worn on a thermal mannequin to a simulated flash fire and is used to predict likely resulting 1st, 2nd and 3rd degree body burns. Note that this is the only test which both tests the whole garment AND makes at least an effort to indicate how well a garment will actually perform in a lab version of a real world flash fire.
It is important to note however that this test is optional in EN 11612 so many primary FR workwear garments have not been subjected to it (though it is a mandatory test in the equivalent standard in North America).
The video below explains how the Thermal Mannequin test works:-
|Find out how to interpret Thermal Mannequin Test Results here!|
How are burn predictions calculated?
|Prediction of 1st, 2nd and 3rd degree burns in the Thermal Mannequin Test use “Stoll Analysis”. Developed in the early 1960’s by Alice Mary Stoll whist working for the US Navy Naval Air Development Centre and investigating FR fabric development. The analysis uses the relationship between heat energy transfer to the skin and time exposed to predict a 2nd degree burn with a likelihood of 50%.The principles of this analysis are now widely used as the basis for measuring effectiveness of flame and heat protective fabrics by predicting likely body burns|
Tests in EN 14116 for Secondary FR workwear
EN 14116 is officially called “Protective Clothing – protection against flame, limited flame spread materials, material assembly and clothing”. This is slightly misleading because most garments certified to this standard will not protect against flames when worn independently of other FR protection.
This standard consist of only one test, the Vertical Flammability Test (EN 15025). This is the same test as the basic flammability test used in EN 11612, but with lesser minimum requirements.
Its purpose is to prove that the fabric does not ignite and continue to burn in contact with a flame. It applies a small flame to a fabric sample suspended vertically and records a visual assessment of how the fabric sample reacts. The results are classified according to three “index’s” – Index 1, Index 2 and Index 3.
Index 1 is the basic minimum, simply requiring no ignition, no melting and no molten or burning debris. Index 2 and 3 have additional requirements including no hole formation greater than 5mm.
Most Secondary FR Workwear fabrics achieve only Index 1 – the lowest classification requiring that the fabric does not ignite and continue to burn and that it does not drip molten debris. However, it does allow the fabric to vapourise and disappear entirely – which many secondary FR workwear garment fabrics subjected to it do… instantly.
A Basic Similarity – and Difference – between EN 14116 and EN 11612
|The ISO 15025 flammability test is used in both EN 14116 AND EN 11612. The requirements in EN 14116 for Index 3 qualification are the same as the minimum requirements for the same test in EN 11612 for primary FR garments. In other words, the same basic flammability requirements along with the requirement that it must not result in a hole greater than 5mm diameter.|
How Effective is the Flammability Test?
There are four problems with this test:-
- In the real world garments are generally not subjected to a very small flame applied to a specific point on the garment without moving as is the case in the test. Flames will often be larger and a user moving will result in the flame attacking different parts of the garment in a short time. In other words the test is a poor reflection of any real world scenario.
- The point of Secondary FR Workwear is that it is worn OVER primary FR workwear… so how indicative is this test? Shouldn’t it be tested in this way?
- An update to the EN 14116 standard in 2015 added a new requirement that the test must also be conducted on garment “components” as well as fabric, with the same minimum performance requirements and specifically that this must include the front fastening and that the fastening must continue to function after the test.However, given that many low cost secondary FR garments (specifically those based on FR SMS materials) would have great difficulty in meeting this requirement, some have been allowed to certify to that new version of the standard but without meeting those requirements… that particular clause has been excluded. So you cannot assume that garments certified to the standard have been subjected to the same tests and met the same minimum requirements. You can read more about this issue here.
- Many fabrics used for lower cost Secondary FR Workwear use thermoplastic polymers treated with FR chemicals (known as “FR SMS coveralls”). Such fabric tends to shrink from the heat of a stationary flame quickly – often too quickly to allow the fabric to ignite. Thus a fabric can pass the test as a result of this rather than because it has particularly effective FR properties.
ISO 15025 actually describes two methods: Method A in which the flame is applied to the centre of the sample and as currently required by EN 14116, and Method B in which the flame is applied to the bottom edge of the sample (optional in EN 11612). Testing shows that method B is much more effective than method A in showing the different performance characteristics of fabrics in terms of a tendency to ignite and burn. This can be clearly seen in the burn comparison video below:-
Method B is arguably more reflective of a real world scenario where workers are likely to be exposed to much larger fires from all angles, flash fires and chemical fires. How a garment – or a combination of primary and secondary FR workwear garments – will perform in such situations is poorly reflected by the vertical flammability test – especially if only method A is used.
How Can Fire Protective Clothing Best Be Assessed?
The best way to determine just how effective any FR garment is in a real-world scenario is to use the Thermal Mannequin Test. This is the only one in either standard that tests the whole garment, simulates real-world situations, and uses established principles to determine the degree of burn a person inside the suit is likely to experience.
The Thermal Mannequin Test
is the only test that can
provide an indication of how Primary and Secondary FR workwear will perform together… as they are
worn in the real world
This is also the best – in fact the ONLY way – to gain an indication of how a combination of primary and secondary FR workwear will perform – which remember is how they are actually intended to be worn. By conducting a thermal mannequin test on the two garments worn together – as they would be worn in the real world – an indication of the effectiveness of the ensemble can be gained.
Understanding FR Clothing Requires Understanding of Heat Energy and How Garments are tested
With the above considered, understanding how Primary and Secondary FR are tested – and how they are very often NOT tested, or only partially tested – will enable safety managers to make better and more informed choices.
The key to understanding FF protection is in understanding heat energy and how it transfers from a source to a worker. The type, source, mass and duration of exposure all make a difference to the type of FR workwear or combination of FR workwear required. You can read more about this here.
In the case of combining different types of protection such as FR and chemical, it is vital to understand:-
- How one can effect the other – specifically that standard chemical suits are made from plastic and will ignite, burn and drip, thus destroying the thermal protection offered by primary FR workwear
- That the basic testing of Secondary FR workwear in EN 14116 is a very poor reflection of real world performance and provides no information about how it will perform when worn in conjunction with primary FR workwear.
- That the certification process does allow specific clauses in a standard to be omitted – so lower cost secondary FR garments have not necessarily met all the requirements in the standard or that other garments certified to the same standard have. Clarification of this by careful reading of user instructions and certification is important in assessing garment effectiveness
- The only test that does indicate how effectively both garments worn together will perform is the thermal mannequin test which provides a prediction of likely body burn in a simulated flash fire. It is the only test that can indicate not only whether secondary FR workwear will avoid compromising FR protection but whether it can actually improve it!
Note that for each test the primary FR garment worn beneath the outer coverall and the parameters of the test (burn duration, time information recorded etc) were the same in order to maintain consistency and allow comparison
Flashspun polyethylene disposable coverall (otherwise known as “Tyvek”) worn over a primary FR garment
Predicted Body Burn
Predicted Body burn
FR treated SMS coverall (certified to EN 14116: Index 1) worn over primary FR garment
Predicted Body Burn
NOTE: There is almost no difference in performance between SMS and FR SMS!
Test 2 and 3 compares coveralls with the same basic fabric (SMS) – but test 3 featured the version with an FR treatment and certified to EN 14116 using the vertical flammability test. Despite the fact that the latter is classed and certified as secondary FR workwear it shows almost no difference – less than 1% – from the non FR treated version!
Pyrolon XT (Lakeland’s Secondary FR Type 5 & 6 coverall over primary FR garment
Pyrolon Plus 2 (Lakeland’s Secondary FR Type 5 & 6 coverall over primary FR garment)
Thermal Mannequin Testing Highlights performance differences
not shown by the testing in EN14116 for Secondary FR Garments
|Tests 3,4 and 5 were all conducted on disposable Type 5 and 6 coveralls that are certified to EN 14116: index 1 as secondary FR workwear garments.
And yet in test 3 – using an FR treated SMS garment the predicted body burn was only marginally lower than the result for the non FR, non EN 14116 garment. A difference of less than 1%!
In tests 4 and 5, using Lakeland Pyrolon Secondary FR workwear which are constructed using fabrics specifically engineered for FR properties, the result was body burn less than half those of the others. The Pyrolon garments showed dramatically lower predicted body burn than all the other garment combinations.
This testing proves that not all garments that are certified to EN 14116 provide an equal or similar performance in a real world scenario and confirms that the vertical flammability test is a poor indication of how effective a secondary FR garment actually is.
Furthermore, the lack of difference between the SMs garment (Test 2) and the FR SMS garment (test 3) – less than 1% – calls into question why any user would pay extra for the FR SMS garments given that they are often considerably more expensive. This testing shows that if you are paying more for FR SMS you are paying for very little difference in performance!!!
CONCLUSIONS… what this means for selection of a Primary and Secondary FR Safety Clothing Combination
There are two major conclusions to draw from this analysis for those safety managers needing to provide workers with both heat protection and chemical protection at the same time:-
- That certification to EN 14116 and the vertical flammability test is a very poor indication of real world performance. Only thermal mannequin testing will provide this.
- That not all secondary FR garments – whether certified to EN 14116 or not – are the same. Thermal mannequin testing provides the proof that only secondary FR workwear specifically engineered for FR properties (rather than SMS “plastic” fabric treated with an FR chemical to try to achieve them – largely unsuccessfully judging by the analysis) is proven to work effectively when worn over Primary FR Workwear.
Therefore it makes sense, from both a health and financial perspective, to use specialist engineered Secondary FR workwear (Pyrolon®, for example) in conjunction with Primary FR workwear to ensure protection is maintained – and even enhanced.
For an effective Health and Safety Plan, ultimately it comes down to selecting the right PPE for the job
When selecting safety clothing for either chemical OR flame and heat protection, ensuring chosen workwear provides effective protection is vital. However, where FR and chemical protection is required at the same time, the problem can be that one can compromise the effectiveness of the other. So choosing the right combination will ensure both types of protection are maintained; failure to consider how Primary and Secondary FR clothing works together could herald disaster.
What are the key issues to consider?
- Check which of the heat resistance tests a Primary FR garment has been subjected to and make sure they are relevant to your application and the heat energy type hazard it presents
- Ensure the heat resistance test classification is suitable for the likely risk or level of heat energy in the application, applying garments with higher level classification to higher risk hazards (if the hazard is high level you need a garment with a higher classification in that heat energy test).
- Where chemical protection is also required DO NOT use standard chemical protective clothing. These garments are made of plastic and will ignite, burn and destroy the thermal protection offered by your primary FR garment. It is vital to source properly certified secondary FR workwear – certified to EN 14116 and to the appropriate chemical protective clothing Type.
- Check certification of your secondary FR workwear; has it been tested to any thermal mannequin testing to prove it actually works? Many low cost garments have minimal testing to the flammability test – sometimes missing out some testing altogether – and exhibit poor real-world performance, showing little difference from standard non-FR disposables, as seen in the test results above.
- Carefully read garment User Instructions for any Secondary FR Workwear to check its certification. Has it been tested to the complete latest version of the standard? Many low-cost versions have excluded key testing required in the latest standard so will not perform as well.
In summary check certification of safety clothing, analyze tests conducted and the results, choose a combination of Primary and Secondary FR workwear based on your application, anticipate all potential hazards by undertaking a thorough risk assessment and work closely with your employees to understand just how they feel they need to be protected.