BY JAMIE C. MORELOCK
Often while performing roof ventilation I can’t help but wonder what it must have been like for our predecessors. These determined firefighters, armed with a six- or eight-pound pickax or flat ax, would relentlessly strike the decking until an adequate-sized hole appeared to allow the smoke and fire to escape. Today, you would be hard pressed to find these axes as our first tool option in roof operations. Moreover, the questionable construction techniques used in modern buildings do not afford enough time to safely ventilate with an ax. I would have to believe the strong-willed firefighters of the past would have been happy to trade the icon of the American fire service for a modern power saw.
For the small-town fire department, the power saw can literally be a lifesaver. Where time is of the essence and personnel at a premium, equipment often plays a vital role in the success of an operation.
BENEFITS AND LIMITATIONS
A power saw is a great multiplier on the fireground. It speeds up forcible entry or ventilation duties and reduces stress and fatigue for our limited personnel. The latter is especially important when considering that the same person must perform numerous functions during a fire incident in a small town.
Any piece of equipment we use has pros and cons. When faced with an emergency, we must determine whether the equipment will be useful in the situation. The power saw is no different. Gasoline-powered equipment by nature has the potential for problems. For this reason, proper and thorough maintenance is crucial. Additionally, the environment in and around a fire is not conducive to supporting anything that requires oxygen to function. Despite its limitations, however, the power saw continues to serve as a fireground “workhorse” every day across the nation.
TYPES OF POWER SAWS
The most common types of power saws used on the fireground are the rotary saw and chain saw. The type and brand are matters of preference. When choosing a model, look for brands that have a long and respected reputation in the fire service or that have been specifically designed for our line of work. Some saws are not designed for the rigors of fire service use. Carefully review saw choices, interview other departments, and have a dealer give you a “demo” saw for a period so your department can test it and make the right choice for its needs.
Contrary to popular belief, size does matter when it comes to power saws. The ability to rotate the cutting edge through some material quickly requires sufficient horsepower. Underpowered saws stall when cutting, delaying operations. The size of the saw should be the largest (horsepower) your personnel can safely operate.
Rotary Saws
Rotary saws used by the fire service generally run from four to six horsepower and weigh between 20 and 25 pounds. Saws with 12-inch blades are most commonly used. In recent years, the larger 14-inch models have become more popular. The rotary saw has a cutting depth of four to five inches, which is more than adequate for forcible entry and ventilation duties (photo 1).
 1. Photos by author, unless otherwise noted. |
Smaller rotary saws are well suited for forcible entry and light ventilation. For heavy ventilation work on built-up flat roofs, a higher horsepower saw is needed. A rotary saw’s greatest attribute is versatility wherein you can easily change blades to cut almost any material.
Chain Saws
Chain saws used in the fire service generally run from three to six horsepower and weigh between 12 and 24 pounds. Bar lengths range from 12 to 20 inches on average, giving this type of saw a much greater cutting depth when compared wth the rotary saw (photo 2).
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Chain saws were once restricted to light ventilation and overhaul. Modern fire service chain saws have large motors, and their chains are designed to cut a multitude of materials found on the fireground. Today’s chain saws, when properly equipped, can easily handle any ventilation operation. Other benefits include the average firefighter’s familiarity with chain saws and the ease of operating the chain saw, especially on peaked-roof construction.
SAFETY
Firefighting is inherently dangerous, and power saws operated by untrained or inexperienced firefighters add to the risk. Start by reading the owner’s manual. It covers all of the saw’s technical aspects and limitations. Blades and chains must be rated for use on your specific saw. You should never modify any component of the saw or force a blade or chain to fit. Serious injury, or worse, could result from such actions. Most manuals include safe operation guidelines. Remember: This book is full of important information, but it will not benefit you if you do not read it.
Saw operators must remain constantly aware of their surroundings. Anytime a saw is in operation, personnel are exposed to a rotating cutting edge. The edge does not differentiate between wood, metal, or flesh. For this reason, wear full protective equipment at all times. Wear safety glasses to protect against flying debris. During training and whenever possible, use hearing protection. Safe saw operations begin and end with personnel who thoroughly understand the saw’s capabilities and limitations and have been trained adequately in its use.
SAW MAINTENANCE
Just like the firefighters who operate them, power saws are expected to work on a moment’s notice and to continue through to the incident’s conclusion. Failure to perform could have serious and negative consequences for the outcome of the incident. For this reason, maintaining power saws is extremely important.
First, read the owner’s manual. It covers topics such as specifications, safety, starting procedures, fuel/oil mixture ratios, trouble-shooting, parts lists, and warranty information. All personnel should thoroughly understand these items before placing the saw in service.
Using one brand of saw will help to alleviate numerous maintenance headaches. Disposable components such as spark plugs, air filters, drive belts, and blades/chains are normally interchangeable. Controls and starting and operating procedures are usually the same. Furthermore, a single fuel/oil mixture will be used, eliminating the need for multiple fuel containers and the possibility of using the wrong fuel.
Maintenance should be done at the beginning of each shift or weekly drill. Begin by removing the saw from the apparatus to a well-lighted area. Look over the entire saw for any damage or defect that may have occurred. Take the saw outside and start it in a safe area. Allow the saw to warm up at a low revolution per minute level before running it at full throttle. Listen to how the engine responds and runs through the entire throttle range. Let the saw idle for a few minutes before shutting it down. This ensures that the cylinder will be free of any unburned fuel and prevent fouling of the spark plug. Now, return to the well-lighted area and look over the entire saw again. After it has cooled down, remove and check the air filter and spark plug. Check the spark gap on the plug. If there is any question of the spark plug’s condition, replace it. Spark plugs are very inexpensive compared with the cost of not having the saw run during an emergency. Top off fuel tanks (and bar oil on chain saws), and check the condition of the blade/chain. On a rotary saw, check the blade guard for a buildup of debris (photo 3). You may need to remove the blade to clean out the gummed-up tar with a screwdriver. On a chain saw, clean the bar, oil port, chain brake, and sprocket. Finally, reset the controls in accordance with your fire department or individual company’s guidelines.
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This procedure may sound a little extreme, but people are depending on that saw to start and function when needed. Spending the extra time now will save time on the fireground, especially when someone’s life may be counting on the saw’s function.
Fuel/Oil Ratio
Follow the manufacturer’s recommendations for fuel/oil ratio when mixing saw fuel. This can vary from as lean as 50:1 to as rich as 35:1, depending on the manufacturer. Too lean a mixture will damage the saw’s engine. Too rich a mixture will prematurely foul spark plugs and cause excessive exhaust. Premixed fuel will have a green or blue tint. If there is any doubt about whether the fuel is mixed properly, dispose of it safely, and mix a new batch.
Most fire service saws run well on gasoline with an octane rating of 87 to 89. Higher-octane fuels, 92 and over, are more stable at higher engine compression but tend to draw moisture over a short time. Moisture in the fuel may cause problems with the saw’s starting and running properly. Unless you use or replace your fuel supply frequently, mix with a lower-octane fuel.
APPARATUS STORAGE
How the saw is stored on the fire apparatus greatly affects how fast it can be put in operation. Saws need to be stored in a single compartment with their associated parts and equipment (photo 4). The compartment should be well vented, large enough to accommodate all of the items in an orderly fashion, and low enough so that a firefighter can remove the saw easily. Saws should not be stored inside boxes within the compartment. These storage boxes take up valuable compartment space and delay saw operations. Also, there has been a lot of debate concerning storing fuel within the same compartment as abrasive cutting discs. If the fuel and discs are stored together, use well-sealed fuel cans (photo 5), and keep the discs on the opposite side of the compartment.
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STARTING PROCEDURES
Starting a power saw while wearing full turnout gear and SCBA requires a different technique than when wearing your station uniform. Fire boots, even leather ones, many times are too large to fit into the rear handle of the saw (photo 6). Forcing the toe of a fire boot into the handle could damage the controls, which usually are made of plastic. Furthermore, bending over the saw in full PPE to pull the starter cord is awkward and creates the potential for back injuries.
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To prevent potential injuries and equipment damage, use a crouching starting position. Developed by Fire Department of New York Lieutenant Michael Ciampo, the technique and its variations involve squatting, like a baseball catcher, and using a knee to hold the saw firmly to the ground.1 This method of starting works equally well for both types of power saws.
Begin by grasping the forward handle with your right hand, keeping the arm straight. Kneel and place either knee on top of the power head, normally over the air cleaner (photos 7, 8). With the left hand, set the controls and then release the compression from the motor. Releasing the compression will help prevent the embarrassment of having the saw roll out from under you or, worse, breaking the starter cord when you pull it. There are two methods for releasing the compression. Some saws are equipped with a decompression valve that opens when it is depressed and closes when the motor begins to fire (photos 9, 10-on this saw, the decompression valve is activated by depressing the blue button). If the saw fires but does not start, you will have to reopen the valve. The second method requires a little practice but will be quick and easy once you get the feel. Grasp the starter cord handle with your left hand and slowly pull it until you feel the cylinder reach the top of its stroke and break over top dead-center. Stop once you feel the cylinder start the down stroke. The exhaust valve will have opened, releasing the pressure, which now will allow you to pull the starter cord without compression (photos 11, 12). Repeat this process for each new pull of the starter cord.
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Most people are right-handed, and it may feel strange to pull the starter cord with the left hand; but with practice, this method of starting a power saw will begin to feel natural.
BLADES AND SAW CHAINS
The type of blade or chain on the saw will determine which materials can be cut and how fast. Initially, just like the saws, blades and saw chains were adapted to our purposes from some other trade. Most of the blades and saw chains used by the fire service are designed and manufactured specifically for fireground operations and are available only to the fire service.
Rotary Saw Blades
Rotary saw blades to cut almost any material are available. In the fire service, we typically use one of three types, depending on the operation. Use a carbide-tipped steel blade for ventilation work and an aluminum-oxide abrasive disc for cutting steel. For masonry cutting, we commonly use a silicon-carbide abrasive disc. Although there are other types of blades, these three are the standards on the fireground.
Ventilation blades for rotary saws are normally 12 inches in diameter, which provides a cutting depth of four inches, and have 12 or 24 cutting teeth that are tipped with carbide (photo 13). Carbide helps to prevent dulling of the tip when conducting ventilation operations. Compared with a demolition blade designed for the construction industry, ventilation blades used in the fire service have a more aggressive tooth design and longer and wider carbide tips (photo 14). The larger carbide tips create a wider cut, or kerf, which prevents the blade from binding. Additionally, a major benefit of the aggressive tooth design is that even if several of the carbide tips are broken or missing, the blade will continue to “rip” the roof decking. This will enable a firefighter to complete ventilation without having to stop and change the blade under most circumstances. This type of blade will also cut the light sheet metal used in some residential and commercial roof systems.
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Ventilation blades have a wide price range. High-end blades cost several hundred dollars, are of a very high quality, and withstand years of service with proper use and maintenance. Another option is to purchase the good-quality low-end blades, which are available for around $50 each, and replace the blade after each use. Ventilation work can be very rough on blades. Hidden structural components made of heavy steel can destroy a ventilation blade on contact, and the materials used in modern shingles often will dull carbide teeth. If there is any usable life remaining in the blade that has been removed, that blade can be saved for training. Since the saw will always have a new blade installed, there will never be any question relative to the quality of the blade the next time the saw is needed.
The abrasive discs the fire service uses on rotary saws are fairly simple and straightforward. The most common sizes are 12 or 14 inches in diameter, depending on the guard size and the saw’s horsepower. Abrasive discs are disintegrating blades that reduce in diameter during cutting operations. For this reason, it is better to use the largest disc possible to reduce the number of blade changes. When cutting with abrasive discs, let the blade do the work; forcing the cut by adding additional pressure provides no real cutting benefit and will only cause the blade to disintegrate more quickly. Abrasive discs can usually remain functional down to six inches in diameter, as long as they retain enough diameter to fully penetrate through the material being cut. Just like the low-end carbide ventilation blades, use them for the operation, and put a new one on the saw when finished.
Some fire departments carry only the aluminum-oxide abrasive discs for steel cutting; others carry the aluminum-oxide and the silicon-carbide blades to add masonry-cutting capabilities to their operations. These blades look similar and are very difficult to differentiate by appearance alone (photo 15-the blade on the right is the steel-cutting blade; the one on the left cuts masonry). It is extremely important to clearly label abrasive discs with a paint pen or by some other fashion to ensure that a firefighter does not inadvertently put the wrong type of blade in the saw. Using the wrong type of disc can result in the disc’s exploding on contact with the material, which will cause delays and potential serious injuries. Also, a telltale sign that you are cutting metal with the wrong blade is the absence of sparks as the blade rapidly disintegrates.
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Multipurpose blades are available for use on rotary saws. These blades will cut numerous materials found on the fireground but usually are very slow. Speed is important for safe and effective ventilation operations; therefore, it is better to match a specific blade to a specific function.
One last thought on blades for rotary saws: If your operations call for the ability to cut steel for forcible entry and roofs for ventilation, consider having two saws-one for forcible entry and the other set up for ventilation. There will be times when forcible entry and ventilation will have to be accomplished simultaneously. Changing blades for initial fireground operations is impractical from an efficiency standpoint.
Saw Chains
Selecting the proper saw chain for fireground duties is critical for effective chain saw operations. Unlike a rotary saw blade, once a saw chain is dulled or has lost its carbide tips, no matter how hard you force the saw, it will no longer cut.
Standard saw chains (the type used for tree cutting) are not suited for the majority of fireground functions. They will dull quickly when cutting through shingles and are easily damaged from fasteners such as nails or screws. At a minimum, fireground chain saws should be equipped with a carbide-tipped saw chain. A piece of carbide is attached to the saw tooth by some means of welding. The standard and carbide-tipped saw chains are designed as a single side plate with the tooth formed by making a 90º bend at the top, which has the appearance of an inverted “L.” Typical saw chains have left and right teeth alternated along the chain’s length.
Carbide-tipped saw chains will more than adequately cut through the shingle-over-wood or rubber-over-wood roofing systems found on residential and older commercial buildings. This type of chain will last for numerous ventilation operations as long as it is not misused. However, since the carbide tip is attached on only one side, it is prone to breakage as a result of repeated contacts with fasteners and other metal objects.
The best saw chains for fireground use are those specifically designed for the fire service. Although these saw chains use carbide tips, their design makes them superior to regular saw chains. Let’s start with their cutting width. Regular saw chains usually have a one-quarter-inch kerf, whereas fire service saw chains cut three-eights of an inch, which helps prevent binding of the chain bar (photo 16). Also, the raker, the piece of steel on the chain that extends up in front of the carbide tip, is much larger on fire service saw chains and helps protect the carbide tip from damage. The most important design feature is that the carbide tip is attached on both sides by two side plates or is attached to a single solid chain link, which helps prevent breakage (photo 17). These features make this type of saw chain extremely durable and capable of cutting through almost any material found on the fireground.
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ACCESSORIES
The appropriate accessories make a good power saw even better. When ordering a new saw, consider all of the optional accessories available and determine which could help to improve efficiency and safety from an operational standpoint. You could also purchase many of the options separately from a local dealer and add them to older saws.
Starting a power saw with bulky fire gloves, especially when wet, can be easier with a large “D”-style pull starter handle (photo 18). This handle allows the saw operators to grasp the starter cord without removing their gloves and virtually prevents them from losing their grip on the handle during starting.
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Saw operators normally need additional hand tools, usually a halligan bar and a hook at a minimum, to support their operation. Transporting a power saw and these additional tools from the rig to the point of operation is not a problem when there are sufficient people to carry them or if you do not need to climb a ladder. Small-town firefighters often perform this task by themselves. The halligan bar and the hook can be married together and easily carried in one hand; the power saw can be carried in the other hand, but this doesn’t leave a free hand to slide the beam when climbing a ladder.
There are a couple of options for getting the saw to the roof. All firefighters operating on a roof should have some type of rope with them. This rope can be tied to the saw and played out as the firefighter climbs the ladder so that the saw can be pulled up once the firefighter is on the roof. However, there are inherent problems with this method. First, the rope never seems to deploy properly; second, if the rope catches on an object, it could cause the firefighter to lose his balance and fall. This option also takes more of the time that we don’t really have.
A better solution is to equip the power saw with a carrying sling. A sling enables you to carry the saw from the shoulder and frees a hand for ladder climbing (photo 19). Attach slings at the rear handle and at the guard. This arrangement allows the saw to be comfortably carried in the vertical, horizontal, or a somewhere in-between position. The best slings are constructed from heavy-duty nylon with well-built snap clips on each end for easy removal. Slings should also be fully adjustable. You can create a sling with 10 to 12 feet of webbing tied into a loop. To create a sling for a rotary saw, start by lacing one end through the rear handle and cinching the webbing on itself. Run the other end of the webbing through the forward handle, place it over the blade guard, and pull it up tight between the belt-drive housing and the guard (photo 20). With this setup, you must carry the saw in a nearly vertical position with the blade down to prevent the saw from rolling over and falling out of the sling (photo 21).The setup used on a chain saw is slightly different. Begin by cinching the webbing around the forward handle. Next, run the webbing through the rear handle (photo 22). Finally, pull both sides of the webbing up, and place them over the shoulder to lock it in place (photo 23). Anytime a power saw is equipped with a sling, the operator must be sure to gather up the sling into the hand holding the rear handle or to remove the sling completely to prevent it from being caught in the blade during operation and to eliminate the chance of tripping on it. Inexperienced operators should always remove the sling prior to cutting. An additional benefit of a sling is that the saw can be hung on the ladder tip or some other object to prevent it from falling from the roof when not in use.
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Chain saws used on the fireground should be equipped with a chain guard (depth gauge) to protect firefighters from the saw chain and to prevent cutting too deeply into structural components. If the manufacturer has not indicated depth setting on the guard, mark it yourself; it will be very helpful. Chain guards should be constructed from lightweight sheet metal for durability and be fully adjustable for various cutting depths (photo 24).
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Consider a few other helpful accessories such as a wrench holder attached to the forward handle. Wrench holders are available on the market (photo 25), or you can build one from a rubber strap (photo 26). Having the wrench attached to the saw reduces downtime should blade replacement or chain adjustments become necessary during operations. Another useful accessory is a blade bag, which can be purchased through most construction equipment dealers or made by a local tarp shop. It is useful for storing and transporting several types of rotary saw blades and replacements for the saw.
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TRAINING
Safe and efficient operations depend on how much and how well the firefighters using the saw are trained. Just like riding a bike, once you have mastered the techniques, you are able to pick up a saw and go to work even after long periods of nonuse with little trouble. However, the best saw operators understand the saw intimately and practice frequently through realistic training scenarios.
The fireground is not the place to receive saw training. Firefighters should be trained and should practice their techniques under controlled conditions. One of the safest methods is to use training props.
Roof simulators (photos 27, 28) can be constructed to represent flat and peaked roofs and can be permanent or portable. Simple additions such as parapets, ladders, bulkhead doors, scuttles, skylights, and vent pipes add to the realism of the prop. Replaceable chop-outs can be made from plywood sheeting. Use wood pallets or replaceable joists to stiffen the sheeting and allow the saw operator to master cutting over and around structural members. Additionally, there should be some type of ceiling “flap” to punch down after the roof has been opened, to ensure that the saw operator has completed the job (photo 29).
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Also, since the height of most roof simulators rarely exceeds more than several feet, injuries from falls are greatly reduced. Another useful prop is a security bar simulator (photo 30), which can be used to practice metal cutting in different positions. Lengths of rebar are inserted into fixtures and held fast by a clamping device, which creates a pattern similar to that found on window security systems. This helps the saw operator to gain confidence in cutting overhead or with the saw upside down.
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Acquired structures also present an abundance of training opportunities for saw operations. However, the structure must be sound, and safety precautions must be in place before training takes place.
For the small town, power saws can be a great asset on the fireground when they are thoroughly maintained, readily accessible, properly equipped, and used by well-trained personnel.
Thanks to Captain David E. Foos, Fremont (OH) Fire Department, for his technical assistance in preparing this article.
Reference
1. “Simple Saw Starting,” Michael N. Ciampo, Fire Engineering, July 1998.
JAMIE C. MORELOCK is a member of the Toledo (OH) Fire and Rescue Division. He previously served with the Fremont (OH) Fire Department. An Ohio-certified fire instructor, he teaches fire tactics for Bowling Green State University and is a member of the Truck Company Operations-Ground Ladders team at FDIC.
