Every PPE suit undergoes rigorous testing before certification and distribution – but what do these tests really tell you about their protective capabilities?
Just because an item of PPE meets a specific standard, that doesn’t mean it’s suitable for your particular application.
Choosing the right PPE for your workforce means understanding the PPE testing processes in detail. Just how protected are your workers with Type 3, 4, 5 and 6 Protective Clothing?
In this blog, we’ll take a look at the different PPE tests for each garment type, as well as the limitations of these tests and their real-world applications
What are the limitations of these tests?
It’s important to remember that PPE tests are conducted in controlled laboratory conditions, which do not represent real-world applications, only state minimum performance requirements and address risks in isolation.
In these tests, the test subject is often wearing other items of PPE (gloves, hood, mask) and the joints are sealed up - often with adhesive tape - to increase the likelihood of a pass. It is also important to understand that a pass in these tests does allow some level of penetration – it does not mean that NO liquid has penetrated. This might be important in the case of highly toxic chemicals that have effects even with low doses.
Liquid chemical protection testing
For Type 3, 4 and 6 PPE testing, the test subject wears an absorbent white suit under the PPE. This will indicate through staining if any of the test liquid penetrates inside the test suit.
Before starting the test, a calibration stain is created by dripping 25µl of liquid onto the white suit. After one minute the area of the resulting stain is measured. This is the calibration stain.
Once testing is complete on three suits, the area of any staining on the inner absorbent suits resulting from penetration is also measured. Provided the total area of staining on the three suits is less than three times the area of the calibration stain, the result is a pass. If the area of staining is greater than three times the calibration stain, a fail is recorded.
The critical point here is that a pass in these tests does allow some level of penetration… which might be important with highly toxic chemicals.
How is each garment type tested?
Each garment undergoes a different PPE test:
- Type 3 garments are exposed to a strong jet spray. The liquid is blasted at “weak points” in the garment such as seam joins and the zip fastening. Hence the need to ensure effective seals at these points.
- Type 4 garments are subject to a shower of the liquid over one minute, whilst the test subject rotates on a turntable and makes a stepping motion. In this case 4.5 Litres of water is sprayed, but there is no pressure on the garment as there is in the Type 3 test.
- Finally, Type 6 garments are exposed to a light aerosol spray. In this case the volume of liquid is much lower, allowing lighter garments of non-barrier fabric to pass.
Understanding of the test details in each of the liquid protection Types 3,4 and 6, helps in appreciating the capabilities and level of liquid-tightness of garments, and in assessing whether a garment is suitable for the specific parameters of your application.
Type 5 garment testing involves a test subject donning the suit and entering a cabin into which sodium chloride dust (salt dust) of various particle sizes is sprayed.
Inside the garment are three small probes that count the dust particles that penetrate inside. The wearer will be asked to stand still, walk on a treadmill and squat slowly for three minutes. During this time, the three probes inside the suit count the particles that penetrate during each exercise. The information from each probe is recorded by a computer and each measurement calculated as a percentage of the dust concentration in the dust cabin. This is the “Inward Leakage” percentage.
The pass/fail criteria is fairly complex. Ten suits of two sizes and five different wearers are tested. Giving 90 individual results (Ten suits with three probes in each suit participating in three “exercises”) and ten average inward leakage per garment results. To obtain a pass:-
- At least 82 of the 90 individual results must have an inward leakage less than 30 per cent.
- At least 8 of the 10 average inward leakage results per suit must be less than 15 per cent
Again, the important point here is that a pass in this test does allow some level of penetration of dust inside the suit… which might be important.
Real-world applications and problems
Taking the above into account, understanding the amount of penetration allowed in testing is crucial. If you know that Type 3,4 and 6 garments allow for some liquid penetration and you are working with highly toxic chemicals, or a risk of higher volume of contamination, you might need to go further than simply wearing a coverall. You may need to consider higher levels of protection and ensure connections between different PPE items are securely sealed.
You also need to understand the chemicals you are working with. For instance, you might use a Type 4 garment to protect against the risk of a chemical shower-type spray– but what if the chemical can vaporise at relatively low temperatures? It’s no longer a question of liquid penetration but of a vapour penetrating through any joins in the suit or ensemble, so a gas-tight suit might be necessary.
For dust protection, the same rules apply. Understand the environment, activity and materials you are working with.
In particular, if you are working with highly hazardous dusts such as asbestos or respirable crystalline silica and especially if the concentration of dust in the application is very high, given that the Type 5 test allows up to 15% penetration in 8 of every 10 suits, a simple Type 5 suit might not be enough. Sealing the joins between the coverall and other PPE worn could be important, and in some cases, you may need to consider using a gas-tight suit.
|The standard for Type 5 garments actually specified this, stating in its introduction: “… it is possible, that this type of clothing does not offer adequate protection from aerosols of highly hazardous substances, where a type 1 garment might be necessary to obtain the level of protection needed”|
Safety Managers and PPE end users need to understand standards properly and what they really mean. Is the chemical suit really right for the job, or should you check the tests conducted actually reflect the details of your specific application? What if you operate in a multi-risk environment and need to address multiple hazards? And don’t forget the donning and doffing process; suits will only protect properly if worn correctly, and a defined donning and doffing process can ensure that additional requirements such as sealing of joins between coverall and other PPE is done properly. A written process with appropriate training can ensure operatives follow the correct process every day?
If you want to select the most effective Type 5 and 6 coverall for your workforce, download our free guide and find out how!