The Apparatus Architect: Part 12

Tom Shand and Michael Wilbur describe ways in which proper planning in the design phase will assist fire departments in specifying the components on a new engine.


In the last installment of "The Apparatus Architect" (October 2002) we discussed some of the concepts of engine company apparatus with respect to compartment and body design. This area of the apparatus with either hinged or rollup-style doors is an expensive toolbox that may or may not meet your department's needs. Careful planning in determining the amount of compartment space that is required to accommodate all of your engine company equipment will pay large dividends when placing your new apparatus in service.

The business end of the engine company is the rear hosebed area that carries the supply and attack lines on the rig. While normally not thought of as an important part of the apparatus, the hosebed and its design in the area that can make or break an evolution on the fireground.

With the advent of adjustable hosebed dividers several years ago, most departments simply load their hose on the new apparatus after making a few adjustments with the dividers so that the hose will fit completely flat in each tier and make sure that the amount of specified hose fits into the bed. This is not the time to decide that you want to acquire five-inch hose in place of the four-inch supply line that you have been using as well as trying to find a place to store your large-diameter hose (LDH) manifold. Proper planning in the design phase, together with the advice of an apparatus architect, will assist you in looking at all of these important areas before you specify the components on your new engine.

As you look at and evaluate some of current trends in fire apparatus design it is becoming clear that we are attempting to do more with less. This can be seen in the types of apparatus that are most commonly being purchased. Many fire departments have determined that instead of operating and staffing a separate engine and rescue unit that a combined rescue-engine is the way to go. Placing all of the normal engine company and some of the rescue equipment on a single piece of apparatus can be done, but something normally suffers. If you get all of the compartment space that you need it means that the ground ladders have to go somewhere else. No problem, you say, we'll put the ladders through the water tank and they will come right off the rear of the pumper. Well, what did we just do here?

The apparatus body must now be as long as the longest ground ladder, so if you are running with a 14-foot roof ladder and a 24-foot extension ladder, the body need to be at least 172 inches long to accommodate this equipment. When you run the ladders through or alongside the tank, this causes the height of the tank to increase, which in turn makes the hosebed higher at the rear as well.

Another factor which impacts the height of the hosebed is the size and configuration of the rear body compartments. Many engine companies are carrying hydraulic rescue tools of various sizes and these will be frequently be located in the rear compartment under the hosebed. A standard compartment at the rear of the body that is 30 to 35 inches high will generally not cause an adverse impact on the height of the hosebed as the top of the water tank will typically be higher than this point on the horizontal plane. Should you specify a full height compartment at the rear that is 55 to 65 inches high, now the entire back end of the engine got incrementally higher and the hosebed is now somewhere in the stratosphere.

The number and size of rear suction and discharge lines also have a large impact on the height of the hosebed from the ground. Booster tanks on pumper typically are a T-shape design with discharge piping run under the T area of the tank on each side. This will generally work for piping up to three inches in diameter. Larger plumbing will require a higher notch in the tank or may dictate that the piping be sleeved through the water tank in some cases. Both of these scenarios will require the overall height of the water tank to become greater and will increase the height of the hosebed floor. When the water tank is sleeved it costs more and could add maintenance concerns.

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