THE SAFE USE OF POWER SAWS
BY BOB PRESSLER
The dramatic increase in the use of power saws on the fireground–for ventilation, forcible entry, and other tasks–has brought to the surface various problems associated with carrying and handling the different saws as well as cutting with them.
It is much easier to transport a power saw–whether rotary or chain–to its place of operation if a strap or sling is used. This is especially true when trying to navigate a portable or aerial ladder. Different lengths of strap are needed for different saws. The sling must be long enough so that the firefighter can carry the saw comfortably. In the photo (right), the sling is long enough so that the saw rides down off the firefighter`s back. This way, it does not interfere with the firefighter`s SCBA.
The saw`s hanging this low may be a problem for some firefighters. When climbing, the saw may swing out to a position that may make it seem as though it will fall off the shoulder. Passing the sling over the head will make the saw ride higher up alongside the SCBA and will prevent it from sliding forward.
Moving from position to position once the roof has been reached may be a problem. One of the most frightening things on the fireground is to be on a roof with next to zero visibility and hearing several saws running out in the smoke. You can`t tell exactly where the saws are, but you know they are close.
Moving on a smoky roof. What is the proper way to move on a smoky roof when you have a saw? If the saw is not yet started, you can carry it. If the saw is running, however, roll the saw on its blade along the roof`s surface. This does two things. First, in the case of a rotary saw, it ensures that the blade has stopped spinning. Even if the tension on the belt is improperly adjusted, once the spinning blade contacts the roof, the blade will stop spinning. Second, it keeps the blade down low, and the saw serves as a guide for the operator. As the saw rolls across the roof, it will find any holes of debris that may be on the roof before you trip or fall into one of them.
Tasks to Be Completed Before Cutting
Once out on the roof surface, you must perform some tasks before cutting the roof surface. Hopefully, if you are bringing the saw to the roof, other firefighters are already on the roof. These firefighters should have addressed the initial vertical ventilation needs. Opening up bulkhead doors or scuttles and removing skylights over the bulkhead or on the roof surface itself all should be done before commencing saw operations.
Other duties for the initial personnel on the roof include a visual check of the rear and sides of the fire building, including any light and air shafts. The firefighter checks these locations for several reasons. Depending on the size of the building, the firefighter may get the first look at the actual fire location, may discover civilians trapped in the fire apartment or on the floors above, or may find victims who jumped and are now in the rear yard or at the base of shafts. The information about fire conditions and civilians who are trapped or have jumped should be relayed to the incident commander.
Once the initial vertical ventilation has been completed, the firefighters operating on the roof should evaluate the smoke conditions and any radio reports to determine if additional ventilation is needed. For fires on lower floors, opening up the natural ventilation openings will probably be sufficient. But if the fire is on the top floor or in the cockloft area, additional venting will be needed.
If additional ventilation is needed, there are two options. The first and quickest is to remove the top-floor windows from the roof level. This may be accomplished by reaching over the roof surface with a six-foot hook or by using a halligan tool with a rope. Tie the rope off to the halligan and lower it until the tool is against the window. Keeping one hand on this measurement, pull the rope and tool back to the roof level. Then throw the tool out and away from the roof while holding on to the measured end. The tool arcs back toward the building and into the window, breaking the glass. It might take several throws to clear out the window.
If this additional ventilation is not sufficient to alleviate the smoke conditions on the top floor or if the fire has extended into the loft area, then the roof must be cut.
Cutting the Roof
Where should the ventilation hole be cut? The proper location of the ventilation hole depends on several factors. Most important is the fire`s location within the building. The hole needs to be cut where it will provide the best escape path for the fire`s heat and smoke. To accomplish this, the hole must be cut as close as possible to the main body of fire.
This location for the hole can be determined by several factors, including bubbling tar on the roof`s surface, smoke pushing through seams in the roof or around vent pipes, and visual observations of the actual fire location. If the fire is blowing out several windows on the top floor of a building, it is pretty easy to narrow down the locations for cutting the first hole. One mistake frequently made is cutting the original hole too close to the outside or parapet wall. With fire blowing out several windows, the hole should be placed farther in toward the middle of the roof`s surface. The rooms that have fire coming out the windows have plenty of ventilation. The rest of the apartment, especially the hallway, has limited ventilation. By dropping back and cutting 12 to 15 feet from the exterior walls, the hole will vent fire gases and heat from the parts of the apartment where the engine is trying to push in. This includes the apartment`s interior hallways. Cutting too close to the exterior wall vents only the same area being vented by the windows.
Size of the hole. Much has been written about what the size of the ventilation hole should be. Dimensions such as 8 2 8 feet or even 12 2 12 feet are often quoted. Although it would be nice to end up with these sizes, it is impractical to cut holes of these sizes initially. A 12- 2 12-foot hole takes more than 72 feet of cutting to make 6- 2 6-foot sections, which are still extremely hard to pull. Keeping sections close to 3 feet 2 4 feet makes them easier to pull once the cutting is completed. It is much easier to cut a small, more manageable hole and to enlarge it than to cut one large hole.
By using a pattern such as the coffin cut, the length of the cuts of the completed sections are still manageable, usually three or four feet, but the hole is still easily expandable to a total of seven or eight feet. Even when using a strip or louver cut, keep the vertical strips at around four feet. The horizontal sections can be longer to ensure coverage of more bays.
Speed is of the utmost importance, especially when cutting the original ventilation hole. The quicker the original hole is cut and pulled, the faster the top floor will be vented; if the fire is in the cockloft, the more quickly the fire spread throughout the cockloft away from the main body of fire will be reversed or slowed down. It is more advantageous to get a 4- 2 4-foot hole cut and pulled than to cut an 8- 2 8-foot hole.
Power saws have made other jobs on the fireground easier, especially forcing heavily secured buildings. It doesn`t matter whether the saw is used on locks or gates. It performs equally well on the hardened steel of locks and the steel of rolldown gates. The biggest decision that the firefighters have to make is which method to use. Should the locks or the gates be attacked? Making this decision is actually pretty easy. If the locks have a point where they can be easily attacked, such as an exposed shackle or even a hockey puck lock, than the lock should be attacked. This would be easier than cutting the complete gate. If, however, the locks are shielded or are of a type that does not present a clear method of attack, then the gates should be cut.
Cutting gates. There are two distinct ways to cut a gate. The first is to make an inverted “V” cut. This cut is started as high and as near the middle of the gate as possible. The cut is drawn down to the outer edges on both sides of the gate. When the two cuts are completed, the resulting cut, shaped like an inverted “V,” makes an opening. This is the one single biggest advantage over the other methods–when you are done with the two cuts, there is an opening.
The other types of cuts involve a variety of different methods. Most involve isolating the lock assemblies from the gate or making a series of cuts to isolate the middle of the gate from the edges. They also involve sliding the slats on the gates after the cuts are made to get a large opening. On older gates, sliding these slats is sometimes impossible. The advantage of this type of cutting is that if the slats do slide easily, the resulting opening is usually taller and wider than the one made using the inverted “V” cut.
One last point on forcible entry and the use of power saws: After the rolldown gates are up or when you are confronted only with an exterior store door, one of the quickest ways to open this door is to cut through the throw of the lock with the saw. The saw blade usually fits right in the narrow crack between the door and the frame. The two-inch bolt usually found is no match for the power saw. The door can then be swung open and entry made.
REMOVING HUD WINDOWS
Power saws, even the rotary type, can be used to remove HUD windows. These board-ups, most times of plywood, usually cover all the building`s openings. From a safety standpoint, it is imperative that as many of these board-ups as possible be opened for the safety of the companies operating inside the building.
The windows can be opened in two ways. If the saw is equipped with a carbide tip blade, the operator must attack the wooden components of the board-up. This will require several cuts in the vicinity of the carriage bolts and the outside 2 2 4. The idea is to be able to remove the outside 2 2 4 and make a large enough hole in the plywood so the head of the carriage bolt can pass through. This frees up the inside 2 2 4, and the board can be easily removed.
The other method involves using a metal cutting blade on the saw. The operator, sawing at an angle, tries to slice off the heads of the carriage bolts completely. Then using the point end of a halligan, the bolts can be driven through both the outside 2 2 4 and the plywood. This again frees up the entire board, which can then be removed.
Carrying a saw on the ladder. (Photo by Robert P. Mitts.)
(Top left) Cutting HUD windows, (right) metal gates or locks on the ground (photos by Robert P. Mitts), and (bottom left) narrow-style doors (photo by R. Torres).
BOB PRESSLER, a 23-year veteran of the fire service, recently retired as a lieutenant with Rescue Company No. 3 of the Fire Department of New York. He created and produced the videos Peaked-Roof Ventilation and SCBA Safety and Emergency Procedures for the Fire Engineering video series OBread and ButterO Operations. Pressler has an associate?s degree in fire protection engineering from Oklahoma State University, is a frequent instructor on a wide range of fire service topics, and is a member of a volunteer department.