Choosing a body material for a new fire apparatus, particularly a pumper, can be challenging and frustrating for an apparatus purchasing committee. Making rational decisions may require committees to sort through the sales hype, advertising claims, and marketing tactics of apparatus manufacturers and their dealers. Smart purchasers are the ones asking questions. Be inquisitive; educate yourself. You may want to know more information than may be offered in nebulous statements and vague specifications. This article does not detail technical and sometimes confusing data and possibly misleading specifics such as weights, tensile strengths, corrosion resistance, flame resistance, mixing dissimilar metals, and the like. Instead, it highlights various body materials, different construction methods, and some common claims a purchasing committee may want to carefully evaluate.
To be able to evaluate available materials, you must understand basic body construction methods. A pumper body of years past was just thata true four-sided body on which optional compartments could be added. Today, with storage space at a premium, bodies havesimply putevolved into side and rear compartment modules tied together by a front panel with upper hosebed side sheets sized to fit the water tank and hose load. Mild or untreated steel is seldom used in today’s bodies and is not addressed here. Galvanized steel (also known as galvanneal or treated steel), stainless steel, and aluminum are common body materials; nonmetallic bodies are available in polypropylene and composite materials. The apparatus purchaser may want to consider more than the advertised material. How bodies are put together and what the entire body is fabricated of may be relevant in the decision-making process.
Bolted-together vs. welded bodies. As an example, a steel or aluminum body can be fabricated by welding or bolting the assembly together. Bolted-together bodies usually have bolt holes predrilled, so the component pieces must fit together very precisely. Welded bodies may be continuously welded or strip-welded together. Although continuous welding is prudent in the lower areas of a body to prevent corrosion, some manufacturers promote and advertise continuous welding throughout their body fabrication. Proponents of the bolted body laud the fit, noting there is no chance for distortion or warping that is common with the welding process. Advocates of welded bodies advertise no seams and no chance of leakage as well as no visible nuts and bolts that may loosen. Both bolted and welded body builders state their own methods of construction are easy to repair. Determining which claims are legitimate is up to the purchaser.
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