Long-term Testing of DuPont™ Nomex®
The official opening of RAGTAL, Luxembourg Regional Respiratory Equipment Wearers’ Training Facility, in 2009 heralded the start of a long-term test on fire protection apparel made of DuPont™ Nomex®. Two years on and the first results from the test are now available.
RAGTAL (Regionale Atemschutz-Geräte-Träger-Ausbildungsanlage), located at Luxembourg, trains fire fighters from across Europe in a wooden-heated fire facility and flash over unit. The training programmes consist of experiencing the correct tactics to be adopted to attack a fire inside a building, fire fighting in complicated conditions such as low visibility, emergency rescue from extreme situations, as well as the use of video cameras to detect people and fires.
With approximately 1,000 trainees per year, the physical stress for every instructor of the Combat Fire Behaviour (CFB) team is quite demanding and therefore reliable performing protective apparel worn during the training programmes is important to the trainers. The focus has been on 50 jackets and trousers made by Consultiv, S-Gard, Texport, Viking and Vorndamme. The suits, all certified under EN 469, have a three-layer structure, with an outer layer made of DuPont™ Nomex® Tough, a membrane, and Nomex® lining and are worn by the RAGTAL fire trainers throughout all practical exercises.
Four flashover training sessions in one day
In 2010, over 1,200 active fire fighters trained in over 60 different scenarios, e.g. resistance to heat and flue gas, gas tank fire fighting, and flashovers in a wood-fired container. Each of these exercises involve a high level of mechanical strain on the garments, considerable soiling and up to four extreme heat surges per day, caused by the ignition of combustibles within the flashover container.
Documented maintenance programme
Due to the intensive wear and tear each garment is subjected to during the training sessions, each item of clothing is given a 5-stage maintenance programme after each exercise day. This programme includes a cold-water pre-wash to remove coarse dirt and is followed by a wash at 60°C.
Next, jackets and trousers are turned inside out, hung up at room temperature for pre-drying, and are then dried thoroughly in a tumble dryer. This is followed by a sight check, both inside and out, including a close look at the membranes.
All stages and results of the care process are put on record, together with any impressions gained by trainers with regard to comfort and practical observations. The results are fed back to the manufacturers, enabling them to improve the designs where appropriate.
Top performance after 80 high-stress usage and washing cycles
Garments of Nomex® fibre have been in use for two years now and have survived 80 flashovers in containers and 20 washes. RAGTAL fire trainer Bernd Schmeltzle sums up the result: “Despite intensive wear in a tough environment, all 50 suits are in perfect condition both inside and out.”
Visually, the dark red jackets and trousers have changed very little compared with their original state. After 24 months the reflective stripes, zips, seams and membranes seem to be as “fresh” as ever. There is no sign of pilling on the outer layer. Only one model displays a minimal amount of abrasion in a certain area, which was apparently due to the design which has since been modified.
“We pass on our impressions and experiences to manufacturers who then use this information for improvements to the suits,” says RAGTAL fire trainer Bernd Schmeltzle, as he comments on the cooperation with the manufacturers.
Personal preferences on specific details
When it comes to comfort, there are no differences between the various suit designs, although RAGTAL fire trainers do have their personal preferences with various features.
One wearer, for instance, prefers wide trouser legs with Velcro®, as this makes them easier for him to don while wearing boots. Another is keen on the generous cut of the knee pad providing a more ample protection zone while kneeling or crawling. Other personal preferences involved various adjustment mechanisms for brace length, various metal buckles, heat-resistant plastic clips, and elastic bands.
Summing up the differences, Bernd Schmeltzle says: “The five systems show that the same design issue can be addressed convincingly in different ways, and each design has its specific strengths.” With a fastening system featuring finger access, for instance, wearers can adjust brace lengths with a single pull, while another solution features a metal clip and spike, for the wearer to adjust the fastening position of the braces at the waistband.
Full-scale flame and heat protection still after 10 years
Flame tests have shown that jackets and trousers of Nomex® have lost none of their protective qualities even after upwards of ten years’ wear. An eight-second intensive flame on Thermo-Man® consistently produced the same result. After several years of wear, protective clothing of Nomex® still offers the same flame and heat protection as it did in its original state.
“It’s good to know that even after many wear/wash cycles we can still rely on the flame and heat protection of our garments of Nomex®,” says Bernd Schmeltzle who is going to continue the long-term wearing test with his fire training colleagues.