I came across this article, and I thought it wise to share with my readers.
How to evaluate protective clothing’s chemical resistance index is very important in our different industries, especially when working with hazardous chemicals.
We do not just order any coverall to use for any task. There are specifications and standards which guides the use of coverall for every specific task.
A coverall is a loose-fitting, one-piece work garment, consisting of a trouser-like portion and a top with or without sleeves, worn over other clothing.
When a worker is assigned to a task which exposes him to chemical risk, he will need a coverall (protective clothing).
The questions now is are:
What kind of coverall does he need?
How can you ascertain that the coverall (Protective clothing) will protect him from the chemical risk he is being exposed to?
Workers are exposed to certain chemicals on-site like, Sulphuric Acid, Acetone, etc.
Now how do you check the suitability of the coverall for the inherent chemical risk on the job?
This can be achieved by carrying out permeation test on the coverall.
The result of this test will be a guide on choosing a suitable coverall for the job.
N/B: The choice of the coverall will also be guided by the MSDS of the chemical he will be exposed to.
Hence, the result of the permeation test will be compared to the manufactures safety recommendation on MSDS for the chemical to determine the suitable coverall (Protective clothing) for the job.
What is permeation
Permeation is explained in terms of penetration. This involves the potential of the chemical to pass through the coverall to make contact with the user of the coverall. The permeation test is carried out with the use of machine.
This specific machine can detect how the chemical permeate through the coverall. The simplified processes can be explained as follow:
- The coverall (Protective clothing) is placed between the testing chambers.
- The surface of the coverall is exposed to an hazardous chemical.
- The inner surface of the fabric is analysed to determine the permeability rate of the chemical.
The result of the permeability test is founded on two parameters; the Permeability rate (PR) and Breakthrough time (BT).
Permeation rate (PR) indicates the mass of the chemical in micrograms, which can be transferred through µg/cm2/min.
Breakthrough time (BT) is the elapsed time between first exposure of the fabric to chemical and the rate of permeation reaching a target value. When measured according to a standard method, the performance of the breakthrough time is a value by which different fabrics can be equitably compared.
These two parameters (PR and BT) is used to classify the protective rate of the coverall. The protective rating is classified thus:
Breakthrough time Class Rating
- 10min Class 1
- 30min Class 2
- 60min Class 3
- 120min Class 4
- 240min Class 5
- 480min Class 6
Here are some standards guiding the permeability rate of protective clothing (Coverall)
- EN 374-3: 2003 record the lowest BT and specifies a normalized permeation rate of 1.0 µg / cm2 / min.
- ISO 6529: 2001 (method A and B) specifies the mean BT to be reported at the normalized permeation rate of 1.0 µg/cm2/min or 0.1 µg/ cm2 / min.
Therefore, before you choose a protective clothing (Coverall) for a job involving hazardous chemicals, ensure that you carry out a permeability test to determine the most suitable protective clothing for the job.