Truck Company Ops: Cutting with the Ventilation Saw
By Mark van der Feyst
Ventilation saws are a great tool for cutting open a roof or the side of a gable end for vertical ventilation. They speed up the process, allowing for quicker evacuation of hot gases, smoke, and unburned particles of combustion. They are also very useful for other special operations—such as rapid intervention—for creating an enlarged opening for rapid extrication of a Mayday firefighter. Using a ventilation saw requires training on the finer details of how it performs, how to use it correctly, and how to optimize it for peak performance.
Some ventilation saws are manufactured specifically for the fire service and differ greatly from a regular chain saw that is used for household or commercial use; the one aspect where there is a major difference is the chain. On a fire service ventilation saw, a specially designed “bullet chain” (photo 1) is used in place of a regular chain. The bullet chain has a beefier look and different cutting properties. This chain needs to be pushed—instead of pulled, as with a regular chain—into the material. The bullet chain produces a fine sawdust instead of wood chips that a regular chain produces. This is also another way of telling if the ventilation saw has a regular or bullet chain.
When operated at a consistent speed, the bullet chain can cut through all types of materials. The speed needed to cut through three inches of material such as wood, shingles, insulation, plastic or metal pipe, nails, or wire is 74 feet per second. This chain speed allows it to drive through the material. To achieve 74 feet per second, the ventilation saw must operate consistently at 10,200 revolutions per minute. When the chain speed drops to 73 feet per second, chain chatter is created; the chain bounces off the material because it does not have the speed or power to cut into and through it. Chain chatter can also lead to kick-back. The bullet chain has been designed as such so that it will not produce this kick-back.
Another distinct feature on a fire service ventilation saw is the exhaust and intake ports. Photo 2 shows the intake port of the ventilation saw. It is very distinctive as it has a black foam cover around the filter. The air intake has been moved to the top of the saw because it helps increase the performance speed and allows the saw to work in smoke-filled environments. The air is drawn in from behind the firefighter, where it is cooler and cleaner than the air in front of him. The exhaust port is also on the saw’s top, which blows away smoke and heat from the saw. The exhaust port works in conjunction with the black plate on the front of the saw body to deflect heat and debris up and away.
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