Have you ever heard someone ask, “If the black box always survives the crash, why don’t they make the plane out of the same material?” Behind every joke is a sliver of truth, and in the fire service, the truth of the matter is that apparatus take a terrible beating. Consequently, polyprene, a material originally used to build water tanks for fire trucks now is being used by some apparatus manufacturers to build the whole body — and departments are beginning to take notice.

It is standard across the industry for tanks used on fire apparatus (excluding 3,000-gallon elliptical tanks) to be made of copolymers. United Plastic Fabricating (UPF), based in North Andover, Mass., and Pro Poly of America, based in Ocala, Fla., have been doing so since the 1980s. In 1998, Pro Poly took it one step further by making fire apparatus bodies using copolymers and, in 2001, paired up with W.S. Darley to further those efforts. When a fire truck body is made of polyprene, it is capable of enduring the same stressors that an aluminum body endures.

Polyprene is a patented material, and while it is not the only alternative material being used to build fire trucks, it is the most popular. Since 1998, Pro Poly has sold more than 1,000 truck bodies to the fire service in the U.S. and around the world. That includes quick-response vehicles, tankers, pumpers and even some aerials. “We have shipped to pretty much every continent in the world and have had very good reception in each country,” said Tim Dean, the company’s president and CEO.

The benefits to polyprene are extensive. The material is a specially formulated copolymer resin consisting of resin ethylene and propylene monomers. It won’t rust, crack or corrode, yet it’s lightweight — lighter than fiberglass or steel. It’s 10 times stronger than polyethylene or polypropylene and is recyclable. It also is 10% to 20% lighter than aluminum and comparable in price. It resists cracking due to fatigue and it also stands up to dings, scratches and dents.

Pro Poly has created a number of standard configurations that can be purchased and customized to a department’s specific needs. Once painted, the so-called PAKs — which include extensions to support side compartments — can be placed on the chassis of choice. The paint comes with a five- to 10-year warranty.

There’s no worry about the smell of stagnant water as there can be in a stainless-steel tank, no leaks due to microbes eating away at the welds, and no corrosion of the body. The poly body can be fixed very easily if damaged, simply by removing the damaged part and welding a new piece into place. Perhaps the biggest benefit is that a poly body will outlast the chassis, which allows it to be remounted on a new chassis, or recycled.

Another highlight of polyprene is its ease of repair. A damaged section can be cut out and a new section welded back on in a short amount of time compared with the extensive and expensive repairs that must be performed on an aluminum truck that has been in an accident.

Poly Imperfections

But polyprene, like aluminum, is not perfect. Its biggest drawback is that it expands and contracts based on the outside temperature. Manufacturers are aware of this and build vehicles to accommodate the expansion. However, this also means that conventional compartment doors are not an option on a polyprene rig. Roll-up doors are the only choice. One owner of a polyprene pumper described the side panels of the truck as “wavy” in the heat.

Another issue concerning polyprene is the paint finish. It is very difficult to get the same smooth finish on a poly truck that is found on aluminum rigs. However, the painting process has improved over the years, and the paint on a poly truck generally is covered by a seven- to 10-year warranty.

Lt. Jim Hynes of the Orland Fire Protection District in Orland Park, Ill., has purchased three polyprene pumpers from Roberts, Ill.–based Rocket Fire, which worked with W.S. Darley. For Hynes, the biggest selling point was corrosion resistance. “I was tired of seeing rigs five-years-old out of service because of corrosion,” he said. As corrosion is no longer a problem, Hynes plans to keep these Poly Bilt rigs in front line service for 10 years and in reserve for five years. They have been in service since June 2009, and so far have experienced no problems, according to Hynes. “Based on their present performance, I would most likely purchase them again,” he said.

Two more fans of Poly Bilt trucks are Bill Webster, chairman of the Rosedale (Ind.) Volunteer Fire Department and Tim Hamilton, chief of Gilman (Ill.) Community Fire Protection District. Both purchased 3,000-gallon elliptical tankers that feature polymer bodies due to weight issues. For instance, Rosedale has many gravel roads in its district and needs to keep the weight of its rigs to a minimum. The Rosedale tanker includes built-in polymer compartments that are integrated with the tank. The entire poly structure sits on a 2008 Kenworth chassis.

Meanwhile, KME also has taken a leap into alternative apparatus materials for its wildland and ARFF vehicles. In 2009 the company introduced bodies using glass fiber–reinforced polyester (GRP). This material is produced using a vacuum-injection process in which resin is injected into the glass fiber. After the material is cured, the result is an extremely strong sandwich construction that can be painted any color. GRP is lighter than metal, corrosion-free, is flame-retardant, shock-absorbent and easy to repair.

Alternative materials are making headway into the fire apparatus market, with the most popular being polyprene. The fact that it doesn’t corrode is its greatest strength, but its expansion in heat and quality of paint finish are preventing it from taking greater market share from aluminum and stainless steel. But as advances continue to be made in alternative materials, expect to see more polyprene-made apparatus entering the market in the coming years.

Jori Wilmoth is a freelance writer based in Lisle, Ill., and is a former marketing representative for a fire apparatus manufacturer.

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