Tools Speed Opening Up
Variety of saws and hammers requires observance of safety rules
Opening up, whether for rescue, ventilation, entry or any other reason, is often a laborious, time-consuming fire fighting operation. As a result, the fire service has been acquiring electric and gasoline-powered tools. But to take full advantage of these tools, fire fighters must be trained to operate them at peak efficiency and with full consideration of safety.
The rescue saw is typical of the power tools that can do a tremendous amount of work in a short time when used properly. With a cutting blade of 12 or 14-inch diameter whirling at about 6000 rpm, this is a saw that demands respect—for both the work it can do and the need for observing safety rules.
A common mistake in using a rotary rescue saw is the failure to maintain normal blade speed. You should allow the blade to feed into the work only as fast as the material is cut. Forcing the blade into the work in a vain effort to speed the cutting only lugs the engine, slows down the blade speed and reduces the cutting effectiveness. In addition, it increases the danger of fracturing abrasive disks. Your ear soon gets attuned to the engine sound associated with the proper working speed, which is somewhat slower than when the blade is rotating without any work load.
Avoid binding blade
With a little practice, you will learn to cut in a straight line—or let someone else operate the saw. Wavy kerfs indicate failure to hold the saw steady. This failure means that the blade is intermittently binding and slowing down, which decreases the cutting speed and increases the danger of blade or abrasive disk breaking. Binding can be avoided by holding the saw steady, starting a cut slowly and then letting the blade find its own path.
Whenever you have a choice on a job, make cuts where the material is thinnest for faster results. For example, if you have to open up a car and you have a choice of cutting just the sheet metal on the top or including the corner posts, it would be quicker to restrict your cut to the sheet metal.
When cutting ferrous metal, the abrasive disk throws out a heavy stream of sparks. Therefore, a charged hose line should be at hand whenever any combustibles are in the area, as they usually are in a rescue situation. Also, if there is a reasonable choice of the direction in which to make a cut, choose the direction that will keep the flow of sparks away from the victim and the greater combustible hazard present. In any case, the victim should be protected by an asbestos blanket— or at least a piece of canvas, such as an old piece of salvage cover.
Remove roof coverings
When opening up the wood deck of a built-up roof, the stones and tarpaper should first be removed from the area you are going to cut. A 12inch blade rotates with a speed at the outer edge of nearly 19,000 surface feet per minute—or about 215 mph. That should give you an idea why a pebble that strikes you at that speed can feel like the impact of a .22 caliber bullet!
Full turnout gear—helmet, fire coat, boots and gloves—and safety goggles must be worn by the saw operator and his helper. Other men should stand clear of the area. A good idea is to store at least two pairs of safety goggles with the saw so that they will be available whenever the saw is used. The goggles should be the type that fits over eyeglasses because in most fire departments there are men who wear glasses.
A set of safety rules for rescue saws was printed in the July 3, 1967, issue of the Fire Service Extension Bulletin, published by the Fire Service Extension Department of the College of Engineering of the University of Maryland. The rules are as follows:
- Provide adequate lighting when using. Unfortunately you can hit what you can’t see—an arm, leg or foot.
- Wear full protective equipment, especially impact-resistant goggles.
- Wear respiratory protection when cutting masonry or other dustproducing substances. A suitable industrial dust respirator or a filter mask is adequate. Silica or lead dust can be as deadly as smoke or fire gases.
- Work with a buddy who will keep you out of trouble. It sounds like a bum joke, but men have been known to climb out on a limb or steel beam, turn around and cut it off. Your buddy should wear the same protective equipment you wear.
- Protect against starting a Fire. Have proper equipment ready, booster line, extinguishers, etc. This is your buddy’s job.
- Follow the manufacturer’s operating and maintenance instructions. Do it right the first time. “After all else fails,” it’s too late.
- Use only blades and parts supplied by the saw manufacturer. These are special blades and parts. Regular blades would probably “blow up” at these speeds.
- Never stand in line with the blade—front, rear, up or down. This is
- where the bullets will fly if the blade “blows up.”
- Test-run a new blade or disk at top speed (stand away) before cutting.
Never bind blade in cut. It will shatter.
- Always start a new cut if you have to change blades. Due to wear, the old cut will be too narrow for the new blade and it will bind and may shatter or kick.
- Never force saw into a cut. Let it chew its way in.
- Tie in tool and ladder if necessary. The saws are heavy and will continue to run (and cut) if dropped.
- When cutting metal with a disk, use water lubrication at the cut. This gives faster cutting, better blade life, fewer sparks.
- Beware of saw kicking back if an obstruction is hit. Brace yourself. The saw could kick you right off a ladder or roof.
- Shut off a saw before adjusting or carrying it.
- Store blades where they will not be struck, or freeze or warp. It’s best to store them flat and dry in a heated part of the vehicle. Never attempt to sharpen a blade. Exchange it. Never use the disks as grinding wheels.
- Never refuel a saw when it is hot. Wait at least 5 minutes.
- Never start a saw where it was refueled. Move at least 10 feet away before starting it.
Rescue saws are available with 4.3 to 6.3 cubic inch engine displacement, developing 4½ to 8 horsepower. All of them have two-cycle engines, but there is a choice of ignition systems—the regular one with points and the solid state system. According to the model, the saws weigh from 20 to 29¾ pounds.
For work in close quarters or where lighter weight and finer control of cutting is essential, a reciprocating saw is desirable. Make certain that the one you buy has a motor suitable for your current type, AC or DC, and voltage. Single, two-speed and multi-speed models are available. Blade speeds range from 800 to 3500 strokes per minute, depending on the model. These saws weigh about 10 pounds,
The easiest way to prepare to saw light metals with a reciprocating saw is to punch a hole for the blade with the pick head of an ax, the pointed end of a forcible entry pry-bar, or a crash ax.
The saw also can be started into material by resting the end of the blade and the bottom of the shoe on the material. By holding the shoe firmly on the work and using it as a fulcrum, the saw blade is gently pressed into the material as the blade cuts a path. The reciprocating saw is then raised until it is vertical to the material. The shoe must be held firmly against the material at all times to avoid breaking blades.
Tips for cutting
Charles Polk Player, chief training coordinator for the Dallas Rescue Service in Dallas City and County, Texas, gave some good reciprocal saw cutting tips in “Removal of Wreck Victims,” a manual he wrote for rescue squads. Some of the tips are:
- Use the shortest blade available. It keeps the blade from hitting hidden obstructions.
- Removal of the shoe may be necessary to get into tight spots. Be sure to keep the spindle away from the work while sawing to avoid damage to the mechanism caused by ramming.
- Use flexible blades.
- For a smoother cut, use a blade with more teeth. Too few teeth per inch on thin material will cause teeth to strip off. Too many teeth on heavier material will cause teeth to clog, get hot and break off.
- Use only enough pressure to bite into the material.
Another type of saw often found on rescue trucks is the chain saw. This type of saw is particularly useful in removing trees and heavy branches that may block a road after a storm and in cutting through heavy timbers in buildings. One manufacturer offers a carbide-tip chain that will cut clay brick, mortar, plaster, asphalt, roofing materials and soft, nonferrous metals.
Although most chain saws are powered by two-cycle gasoline engines, electric models also are available. The blades for gasoline chain saws range from 12 to 72 inches, while blades for the electric models are from 13 to 25 inches long. The gasoline saws weigh from 10½ to 37 pounds, and electric chain saws run from 16½ to 18½ pounds. In the gasoline models, you have options of direct drive or a gear drive, and solid state ignition is available on some models. The displacement of the gasoline engines ranges from 3.3 to 8.5 cubic inches with up to 15 horsepower.
In making cuts through thick material, such as a tree trunk, you may have to pound a wedge into the kerf to keep the blade teeth running freely. This happens when the tree—or a large beam—is resting with an uneven distribution of weight, causing the upper area to be in compression.
The electric models are preferable for working in confined areas, such as tunnels, because they do not create the carbon monoxide problem of gasoline engines. If a gasoline saw is used in confined areas, a smoke ejector should be used to provide a rapid change of atmosphere. If this cannot be done, then the operator should wear selfcontained breathing apparatus. If there is a victim trapped in the area, then he also must be protected against breathing the exhaust fumes.
Another saw that can be useful for some jobs is the common, carpentertype circular power saw. These electric saws are available in many models and sizes. For most fire department work, a 7 1/4-inch blade should be large enough, and the weight saved over models that use larger blades is a distinct advantage in many rescue and overhaul situations. A combination blade will do both crosscutting and ripping, but it is well to consider using a strictly crosscut blade because nearly all emergency work will be crosscutting.
The saw should be started before the blade touches the material. Then push the saw slowly and firmly into the work, but be careful to avoid any excessive pressure that will slow the normal cutting speed of the blade. Also, saw in a straight line to avoid binding the blade and creating a kickback of the saw.
Abrasive disks are available for these saws, but there is little reason for them in emergency work as your other tools will be more efficient in most cases.
Gasoline-engine circular saws of the type just discussed also are available. However, the electric models have more desirable characteristics for fire service use.
Another power tool that can be used to advantage for both rescue and forcible entry is a rotary hammer, sometimes called a demolition hammer. Models are available with electric motors or gasoline engines. These tools are made to use bull points from 11 to 24 inches long for penetrating masonry walls. The weights of these rotary hammers range from about 14 to 26 pounds, with the gasoline models and the larger electric hammers both weighing the maximum.
In using these hammers, you should wear goggles and full turnout gear to avoid injuries from flying pieces of masonry. As an added precaution, other fire fighters should remain some distance from the man using the tool to minimize the possibility of being struck by fragments.
Whenever power tools are used, every man in the area—as well as men operating tools—must constantly be aware of the dangers associated with every mechanical tool and observe safety precautions at all times.