September 1, 2007
When it comes to PPE, “layering” is not a fashion statement. It can be a cost-effective, practical way to clothe your workers as they move between tasks with different hazard ratings. The right combination of garments increases protection against heightened risks. In addition, air, a free and ever-present isolator, figures into the safety equation. Learn how to multiply your defense against hazards by layering FR clothing.
An example of layering
In a perfect world, workers would wear maximum protection FR clothing throughout their shifts, and executives would never fuss about costs of such protection. In the real world, however, protection must be balanced with worker efficiency and economics. Layering becomes one possible solution, as seen in the following example, which focuses on arc hazards, provided by safety consultant Eddy Valdes1:
A mechanic in an industrial plant is called to examine a conveyor system that is down. The mechanic was in the shop rebuilding a pulley with new bearings at the time, so he is wearing his typical uniform that conforms to NFPA 70E Hazard/Risk Category (HRC) 2 standards. Upon arriving at the scene of the breakdown, he sees that the conveyor system is overloaded with packages being moved. In troubleshooting the breakdown, he moves to the MCC area. He opens a live 600V bucket to assess the failure from within the electrical system and finds heaters and relays that have failed. He decides he’ll need to replace the bucket and swap it out with a new one, so he dons his HRC 2 rated coverall over his HRC 2 uniform, which provides a layered HRC 3 level. This layering of protective clothing (along with the appropriate PPE) satisfies the NFPA 70E standard for electrical safety requirements for arc protection to engage in the live electrical repairs in the area.
Here we see how two types of garments are used in a 15-minute span and caused minimal downtime in donning and doffing of the coverall to impact the operation. These types of scenarios can happen often throughout an operation. So that workers don’t have to wear heavier type HRC 3 garments throughout their shifts, train them to use additional protective clothing/garments, as dictated by the specific situation.
The use of additional layering with the coveralls serves two functions: It keeps the worker in compliance with the required safety regulations; and it provides the comfort and flexibility needed to complete the task.
Protection with comfort
The key to the above example is analysis that shows 67 percent of all tasks at a typical industrial company rank at or below HRC 2, with the bulk of that time spent at HRC 1 or 0. The example shows how the worker is adequately protected with a primary layer, possibly a 7-oz. FR shirt and a 9.5-oz. FR pant, during duties that occupy two-thirds of his time. Arc ratings are 8.7 for the shirt and 12.4 for the pant, protecting the worker in HRC 2 environments.
When moving to the conveyor breakdown, the additional coverall boosts the protective clothing to HRC 3, providing heightened protection with acceptable comfort and mobility. It is then easy to shed the coverall when returning to more common duties.
Having to wear heavy gear for extended periods could affect worker comfort as well as the motivation to stay compliant. This example is not to negate the importance of heavy gear for intended uses. It simply shows that there are other paths to protection, particularly for workers who do not need HRC 3/4 for many of their typical duties.
Air factors in
Layering’s results are not simply a matter of adding manufacturer specs for flame resistance. Air, in ever-present layers amid multiple garments and as the ultimate buffer between garments and skin, adds positively to the safety equation. Loose fit, not snug fit, creates a vital air “envelope” for additional insulation.
Test results show the inter-garment air layer contributes to an aggregate flame resistance surpassing the combined protection ratings of the two FR garments. However, note that there is no measurable standard for the extra protection afforded by air trapped between garments due to the many variables involved with individual situations such as amount of air trapped, tightness of garments, size of wearer, etc. The safest assumption is that air can provide protection above and beyond the layered garments, but the actual combined rating of the garments worn should be used as a maximum number before entering any hazardous duty.
Workers may require multiple garments to maintain safety while performing multiple tasks within a day’s work. There may be many pieces of clothing, but only one philosophy: proper protection at all times for changing risk. Layering is a sensible answer that combines comfort, convenience and safety.
FOOTNOTE 1 Facilities and safety consultant Eddy Valdes is head of World Class Solutions Group (www.wcsgconsultants.com).