Joined: 22 July 2009
what will be the overall ATPV value if I use a 10 cal/cm shirt and 15 cal/cm jacket together. whether it will be direct summation I.e. 25 cal/Sq. cm or it will be more.
Why i am interested in 2 clothing instead of single clothing of 25 cal/sq.cm is because we work in humid and high temperature environment.. hence if there is provision for 2 clothing. Then shirt can be worn as normal everyday wear and whenever there is switching, jacket shall be used.
Joined: 28 September 2007
As a rule of thumb it would be in the region of 30% to 50% higher than the sum of the APTV value of the 2 garments.
There are a number of factors that are involved such as material types, weight, weave and fit. Therefore the only sure way of knowing is to have an arc test carried out on the assembly, usually done at Kinetrics in Canada.
Some manufacturers are starting to do this, so if you know the material type you can approach the maunfacturer and they may be able to advise. This will be much easier to do if the garments you select utilise the same materials such as all Indura or all Nomex.
You can of course mix different types of material but the likelihood of coming across someone who has already tested that assembly is very low.
If you are working in higher temperature environments then it may be better to look at the treated cotton fabric such as Indura or Proban or a blended fabric like V50 or Megatec as appose to the Aramid fibres.
You will also get an improved performance if you wear standard cotton underneath arc resistant overalls usually in the region of 10 to 20%. The arc resistant clothing must provide 100% coverage of the undergarments, it depends of if you feel you need to wear arc resistant clothing as standard and provide extra layers for specific more high risk activities or if you just need arc resistant clothing at specific times. Dupont do provide some data for wearing Nomex over the top of cotton and the improved performance.
Which ever method you use, I would do some wearer trials of different options as feedback from those that are to wear the PPE is critical in getting them to wear it.