USE OF THE AIR CHISEL IN FORCIBLE ENTRY OPERATION

The air chisel long has been recognized for its performance as a rescue tool used in vehicle extrication. This lightweight but powerful tool is capable of making precise cuts through structural components of vehicles to free accident victims. The same qualities that have made the air chisel an excellent extrication tool also make it a very effective forcible entry tool for structural firefighting.

The air chisel is particularly effective in cutting sheet metal that forms the skin of swinging metal-covered doors, interlocking slats of overhead rolling doors, and sectional panels of overhead folding doors. Even the inexpensive “muffler-gun” variety of air chisels is quite effective in cutting through the light-gauge, sheet-metal skin of most doors. Specialized air chisels designed specifically for rescue work, however, are much more versatile for forcible entry. These heavy-duty tools have been “beefed up” to withstand the rigors of cutting at high pressures (250 to 300 psi) for extended periods and have the power to cut through hinges and strong bolts that fasten door and window bars.

AIR CHISEL VS. GASOLINE-POWERED SAW

The gasoline-powered rotary saw is the primary metal-cutting forcible entry tool of the fire service. A saw, equipped with an aluminum oxide blade, can cut through heavy locks, channel iron, and security bars that will defy the most powerful air chisel. Although the air chisel will never replace the rotary saw, it has some advantages that make it the tcx>l of choice for certain forcible entry applications.

Light weight. A five-lb. air chisel weighs considerably less than a 32-lb. power saw. This weight advantage allows an operator to safely cut over his head with minimal fatigue.
Always starts. An air chisel can be operated in heavy smoke and oxygen-deficient atmospheres that will “choke” a gasoline saw.
Control. The size and weight of a rotary saw can make it difficult to guide it through precise cuts. The gyroscopic effect of a blade spinning at several thousand rpms can make a saw unwieldy. An air chisel, on the other hand, is relatively easy to control after a few hours of training and practice.
Less of an ignition source. Although an air chisel can produce sparks when cutting ferrous metals, it is much less of an ignition source than a power saw. The gasoline saw produces a shower of sparks because its abrasive blade actually grinds a cut into metal. A saw can also ignite flammable vapors that come in contact with its internal-combustion engine.
Doesn ‘t run on. An air chisel stops cutting immediately when its trigger is released. By contrast, a saw blade continues to spin after its throttle is released, which is a common cause of accidental lacerations.
Mobility. An air chisel’s size, light weight, and ease of control allow it to be operated from positions that could be dangerous for a power saw: on ladders, above an operator’s head, and on the narrow ledge of a loading dock outside a closed overhead door.

Although an air chisel is inherently safer than most other power forcible entry tools, it can injure its operator and those working nearby. Follow these simple safety practices:

Wear eye protection designed to shield the eyes from metal fragments.
Wear protective clothing to protect skin from jagged metal and sharp edges around the inside of an access hole.
Wear substantial gloves, not only to protect against lacerations but to reduce operator fatigue by dampening the tool’s impact on the hands.

AIR SUPPLY AND CONSUMPTION

Many fire departments are capable of supplying air power to their pneumatic tools through a hose reel connected to a large apparatus-mounted compressed air tank. This arrangement is excellent for most vehicle extrications but may not provide the mobility needed when the air chisel is used for forcible entry in and around a building.

An air chisel will be much more useful for forcible entry operations if it can be easily carried with its own supply of compressed air. This is accomplished simply by connecting the air chisel regulator directly to an SCBA cylinder and supplying the chisel with a 10to 20-foot section of pneumatic hose. The regulator, which can be specified to accept both 2.216and 4,500-psi cylinders. reduces the air pressure from the cylinder to an operating pressure. It is adjusted to cut different thicknesses of metal.

Air consumption varies with the operating pressure and duration of application. One manufacturer recommends a regulator setting of 100 psi to cut light-gauge sheet metal. At this pressure, the tool will consume approximately four cubic feet of air per minute (cfm) and exhaust a 45-cubicfoot air cylinder in a little over 10 minutes. Cutting heavy-gauge metal can require a regulator setting as high as 250 to 300 psi. At this rate, an air chisel will exhaust a 45cubic-foot cylinder in five minutes.

Extra air cylinders should be provided when an extraordinarily heavy door or hinges must be cut. Remember, however, that an air chisel, like any tool, has its limitations. It is not a substitute for jobs that call specifically for a rotary saw, and members should consider the logistics involved in carrying extra cylinders (or moving a cylinder cart) to a tactical objective. The idea behind the air chisel in forcible entry applications is to rapidly attack a door at its weakness (sheet metal) rather than at its strong points.

FORCING OVERHEAD DOORS

Overhead doors at commercial occupancies usually are void of locks, latches, or pull chains on their exterior. They typically are lowered and locked by someone who exits the building through a swinging door. An air chisel is an excellent Ux)I for cutting openings in a metal overhead door to gain access to its locks, latches, and chain. This allows the door to remain relatively intact and can be opened completely by its own raising mechanism.

Cutting a steel overhead rolling door from an awkward position on a narrow loading dock ledge. The firefighter cuts a vertical slice in the edge of the door along its track, through the interlocking slats.

The cut section is pushed for access to the pull chain. Bolt cutters are used to cut the padlock securing the chain to the door track.

and lower right) The chain is pulled out of the opening and operated from that position to raise the door, intact and fully opened.

(Photos by Tom Kinney.)

Forcing a steel overhead folding or sectional door, A square opening is cut into the second-from-bottom hinged section. The opening is large enough for the firefighter to operate inside the door. (The flap is pulled outward here for demonstration purposes.)

The firefighter uses bolt cutters to cut the padlock that secures the sliding latch bar in the track or an air chisel to cut the padlocked latch bar.

(Photos by Bill Lyons.)

Overhead rolling doors. A prefire survey is likely to reveal that pull chains are most often found on the left or right of overhead rolling doors in a particular response district. If there is a pattern of consistency, begin on the prevalent end by cutting a vertical slice in the edge of the door along its track. Continue cutting through the interlocking slats until the cut portion can bend, allowing it to be pushed inward to provide an opening to look for the pull chain. If no chain is observed, repeat the same vertical cut on the other side of the door. Once the chain is spotted, enlarge the vertical cut upward and downward until it yields an opening large enough so that you can operate the chain to raise the door.
Overhead folding doors. Overhead fold ing or sectional doors usually are locked on the inside by a latch bar that slides into a hole in the door’s guide track. Latch assemblies are fastened to the framework of the door with sheet metal screws and usually are located on both ends of the second (from the bottom) hinged section. Cut an opening on each end of the second section large enough to enable you to reach in and operate the latches. Cut only the sheet metal skin; avoid any framework. If the latches are padlocked in the tracks, cut the locks with bolt cutters or cut the latch bars with the air chisel.

Forcing a heavy steel door at the rear of a mercantile occupancy. The firefighter shears the heads off the carriage bolts that fasten the latches and security bars to the inside of the door.

The headless bolts are driven back through their hole with the spike of a halligan tool.

The hinges are attacked with an air chisel.

The top hinge is cut last to maintain control of the door.

(Photos by Tom Kenney.)

Forcing a metal-dad door locked by doorknobs or panic hardware. The fire-fighter cuts a flap out of the outside sheet metal skin and pulls out insulating material.

Then he cuts a flap in the inside door skin between the reinforcing ribs.

The firefighter reaches in to operate the doorknob or panic bar.

(Photos by Tom Kenney.)

FORCING SWINGING DOORS

Opening the rear of mercantile occupancies can be one of the most difficult forcible entry challenges for a ladder company. The backs of stores typically are secured with heavy steel d(x>rs equipped with several strong locks. For additional security, a business often will install sliding latch bolts on the inside surface of a d(x>r and use a heavy wtxxl beam, steel pipe, or channel iron as a bar across the door opening. The bar is held in place by U-shaped “stirrups” fastened to the d(x>r or the wall on each side of the doorway. When surfacemounted locks and stirrups are fastened with carriage bolts, the bolt heads can be readily observed on the outside of the dtxir. Shear the heads off the carriage bolts with an air chisel and then drive the headless bolts in through their holes with the spike of a halligan tool. This will unfasten whatever device they were holding on the inside of the door. Certain lock assemblies indicate that a door may be more easily forced at its hinges. A heavy-duty air chisel has the power to rapidly cut through substantial hinges, allowing a door to be pried open from its hinged end.

Some metal-clad doors can be quickly opened by operating their locks and latches through an opening cut in their sheet-metal skin. This technique is particularly effective for forcing doors that are locked on one side to prevent entry but can be opened from the other side by turning a doorknob or pushing a panic bar. Fire companies ascending a stair shaft in multistory buildings are frequently hampered by doors that are locked on the stair side to discourage undesirables from using the stairways for criminal activity. Conventional forcible entry (prying) on these fire doors can be difficult, exhausting, and time consuming. A rotary saw can be used to cut holes in the door, but an air chisel is more precise and a lot lighter to carry up several floors. Cut a flap out of the outside skin of the door, tear out any exposed insulation, and then cut a second flap in the inside skin between the reinforcing ribs.

The flaps must be large enough to enable you to reach inside the opening to turn a doorknob or actuate the panic hardware. Cutting a fist-size flap in between reinforcing ribs of a very substantial fire door may not be possible because the ribs are spaced too closely together. Cut a section of rib (usually 22 gauge) out of the door or try an opening directly above or below the lock. This area may be clear of ribs for five to six inches to allow space for the lock assembly.

Homeowners and occupants of multi family residences frequently fortify their doors by installing an inexpensive dead bolt that is separate from the original doorknob locking mechanism. A tubular dead bolt that projects one to two inches into a door jamb is the most common of these “add-on” locks. It takes only a few seconds for a heavy-duty air chisel to shear the lock cylinder of a (typically inexpensive) tubular dead bolt off the face of a door. The dead bolt then can be opened by substituting a screwdriver for the action of the lock cylinder.

STOREFRONT SECURITY GATES

An air chisel can quite effectively slice through interlocking slats of roll-up security gates. It, however, is not always necessary or appropriate to cut and remove metal slats. One manufacturer of lock assemblies attaches the hasp for the American 2000 series lock to a separate steel backing plate | rather than welding the hasp directly to the track of the gate. A heavy-duty air chisel can rapidly cut this backing plate where it is attached to the track. On most installations, only the top and bottom edges of the backing plate are welded to the track, making it possible to cut the entire lock assembly (lock, hasp, retaining pin, and backing plate) off the gate in about 20 seconds. If the backing plate is welded to the track on all four edges, the operation will take longer, but it will yield the same results: The gate can be raised intact without damaging the lock assembly, slats, or track.

WINDOW BARS

An air chisel will quickly shear through lag bolts that fasten security bars to a masonry wall. Deliver a momentary burst to drive the bit in between the wall and the flat tab where the bars are bolted. A second burst will shear the lag bolt in a few seconds.

An air chisel can be very effective in certain forcible entry applications. Its value, however, must be judged by individual lire departments based on prefire familiarization of door and lock installations in their jurisdictions. The effectiveness of the forcible entry techniques detailed in this or any other article should be validated by each department through training and prefire familiarization.