Miami-Dade (FL) Fire Rescue (MDFR) designed and built firefighter training props to instruct personnel in the techniques of cutting laminated impact resistant glass, vacant property security panels, carriage bolts, HUD curtains, hurricane shutters and overhead doors.MDFR has formed alliances with window and door contractors to obtain windows and doors with laminated glass as well as overhead, sectional and overhead shutters.While most overhead doors are old-for-new doors, laminated glass doors and windows are mostly brand new; they cannot be installed because of errors in their dimensions or the design specified by the architect.
For years, MDFR firefighters have attempted to install C-clamps or otherwise stabilize laminated glass windows and doors upright while personnel swing axes and hammers or operate chainsaws to penetrate them.Fortunately, no one was injured, but no one realized the greatest risk of cutting glass.It wasn’t until the Palm Beach County (FL) Fire and Rescue Department filmed a training video that the two departments learned about the respiratory hazards of inhaling glass dust.During production, the videographer will freeze the video and zoom in on the image.What was observed was disturbing: When firefighters inhaled, glass dust could be seen entering their mouths and noses.As a result, both Palm Beach County and MDFR require personnel near glass cutting to use self-contained breathing apparatus (SCBA).
In photo 1, the frame of the fixed glass cut struts was welded together by its designer, Captain Juan Miguel.To clamp doors and windows, the U-clamps are made of heavy duty channel iron and fitted with T-handle screws.The clevis secures the glass door or window to the bottom sill and to the top header, which slides up and down in the channel of the upright bracket, like an overhead roller shutter.As a result, props have the unique ability to fit almost any size window or door.In photo 2, MDFR personnel use (from right to left) a battery-powered rotary saw, a gasoline-powered rotary saw, and a reciprocating saw to practice cutting techniques.Photo 3 is a close-up of the top header channel and pulleys added to facilitate raising and lowering the top header.Photo 4 shows the expansion prop containing a column of exterior stairs.
A second portable prop can be installed in the window opening of the MDFR training tower, or in the acquired structure, for training ventilation-entry-isolation-search (VEIS) techniques.This prop uses road signs on the inside and outside of window openings.Ratchet straps squeeze road signs together to hold them in place.In photo 5, the window to be cut is in a clevis, fastened to the bottom of the exterior road sign.In photo 6, the top of the window is clamped by a clevis that engages the outer flange of the road sign and slides down into place.In Photo 7, firefighters use a battery-powered saw to cut a laminated glass window that is secured by portable struts in the window opening to obtain the structure.In photo 8, the portable glass cutting prop is attached to the window with road signs and ratchet straps.Here, a firefighter at the top of an aerial ladder begins cutting glass to activate VEIS.
No inspection of glass cutting props is complete without an inspection of the glass.Annealed glass is the most common glass encountered by firefighters, such as flat glass and “float glass.”When affected by or exposed to fire, annealed glass can shatter into large pieces that can cause injury or death, especially if they fall from the upper floors of high-rise buildings.Broken annealed glass shards can also be a hazard to firefighters when they remain in the upper part of the window frame.When firefighters break annealed glass display windows – which still exist in older buildings – they have to be very careful to clear the tops of the window frames.If they didn’t, heavy, thick, jagged shards of glass would hang over their heads like guillotine blades; they could fall without warning.
The properties of annealed glass can be altered by heating and then cooling in a furnace.The time, temperature and cooling rate of the glass in the furnace determines whether the glass is fully tempered or thermally strengthened.This heating and cooling process compresses the outer surface of the heat-strengthened and tempered glass, increasing its strength.Both heat-strengthened and tempered glass are stronger and safer than annealed glass, but they have different breakage characteristics.When heat-strengthened glass shatters, it produces shards similar to annealed glass, but tends to remain inside the window frame.When shattered, tempered glass shatters into small crystals that tend to fall off the window frame.
For several years, jurisdictions along the Gulf and Atlantic coasts have mandated the use of storm shutters or laminated wind and impact resistant glass in new construction.Laminated wind and impact resistant glass consists of a central layer of a strong, transparent polymer such as polyethylene butyl sandwiched between two sheets of heat-strengthened or tempered glass.Both layers of glass can shatter on impact, but the plastic inner layer resists penetration and keeps the window intact.Expect more than one piece of laminated glass, especially in tall buildings.To save energy, high-rise buildings often have insulated windows, which consist of two sheets of tempered or heat-strengthened glass filled with air, argon, xenon, or other insulating gas.
The presence of laminated glass is a critical factor and should be determined at 360° magnification.If present, it means that personnel will be operating in a building that is essentially windowless.In photo 9, firefighters mistook the laminated window for a traditional glass and attempted to break it with a roof hook.Gently tap the laminated glass with a metal tool to identify the laminated glass without damage; if you hear a dull pop, it is likely to be the laminated glass.
While ventilated chainsaws equipped with carbide chains are arguably the fastest and most efficient tools for cutting laminated glass, it is practically impossible to cut human-shaped openings with hand tools, especially within smoke-filled structures.However, hand tools can be used to cut small openings to reach and operate the latch.For example, if laminated glass windows are installed to specification, it is likely that each bedroom will need to have an “escape” window that can be opened and opened from the inside.Additionally, sliding doors and French doors can be opened in a similar manner.Cutting with hand tools involves striking a flat axe with a mallet for cutting or chiseling.
In modern office buildings and hotels, there are few windows that can be opened for ventilation.Some fixed sash or glass curtain wall buildings may have windows that can be opened for ventilation with an Allen key or special key.Likewise, old building codes required firefighters to break some tempered glass windows.Building management doesn’t want tenants to open their windows and let the very expensive air to heat, cool and humidify escape.Without the ability to open windows, ventilation operations for firefighters will be difficult.
Consider this common scenario: a shorted power strip can start a fire under a desk in an office suite workstation or cubicle.Every window in the building is laminated glass, and none of them can be opened.Since almost everything in the compartment is made of petrochemical synthetic material (plastic), the smoke from the early stages of the fire is already dark and pungent.Soon, the fire will spread to office chairs and soundproof cubicles, both filled with polyurethane foam and covered with vinyl or polyester fabric.Ultimately, the heat from the fire activated one or more sprinklers, stopping the fire from progressing, but no smoke was produced.
Sprinklers rarely fully extinguish a fire, leaving it smoldering or incompletely burning.Considering that carbon monoxide (CO) is a product of incomplete combustion, office suites are filled with thick, water-cooled fumes that contain dangerous concentrations of CO.Since gasoline-powered saws cannot operate in smoky, oxygen-deficient environments, today’s battery-powered saws are ideal for creating vents in laminated glass windows.
The ultimate solution to ventilating buildings with fixed, insulated, impact-resistant windows is a properly designed and operated smoke control system.These include a series of carefully designed powerful fans, large supply and exhaust ducts, and dampers to control the movement of air and smoke.
MDFR staffed its medical rescue company with an officer and two firefighters.These units are equipped with tools common to ladder companies and thus perform the function of ladder companies in structural fires; they are responsible for forced entry and searches.For years, medics were equipped with gasoline-powered chainsaws and rotary saws until concerns about gasoline fumes entering the patient compartment caused them to be removed.Since the gasoline saw was removed, MDFR has been looking for tools to restore the rescue company’s forcible entry capabilities, specifically cutting the anti-theft rebar commonly found on doors and windows in the Miami area.The department evaluated rotary and reciprocating saws powered by nickel-cadmium (ni-cad) batteries.Although these early battery-powered saws could cut laminated glass in smoky and oxygen-deficient environments, the glass had to be “softened” by hitting the glass with a tool, breaking the inner and outer layers of the glass so that the saw basically just cut the aggregate in the middle material core.While portable and quick to deploy, none of these tools perform as well as a gasoline-powered saw.
In 2019, the department asked the Technical Rescue Team (TRT) to evaluate a new generation of lithium-ion (li-ion) battery-powered dicing saws from two manufacturers.Unlike NiCd batteries, Li-Ion batteries do not reduce the power of the tool when they lose their charge.Although they were used to cut rebar in collapse rescue operations, it was soon discovered that the new battery-powered saws could cut anti-theft rebar almost as fast as gasoline-powered saws.In photo 10, a firefighter cuts rebar in the anti-theft rebar cutting pillar.Based on the positive feedback from TRT, the department is confident it has found the high-performance portable saw it was looking for for retooling medical rescue.These saws are now the “go-to” equipment for every cutting challenge and have helped save lives in the process.
Lightweight, easy to control, and durable, these saws work well when cutting in tight spaces or close to victims.They are good at abrasive cuts.During the evaluation process, the department found that the best saw blade (technically not a saw blade, but an abrasive cutting disc) was a vacuum brazed diamond-inlaid saw blade.In addition to the cutting quality of the diamond edge, these blades also cut very thin cuts; therefore, the saws have less kinetic wear friction than those equipped with conventional diamond segmented saw blades.Both brands have a 9″ diameter blade with a 3.5″ depth of cut.
Each company ships four batteries; one is stored in a dorm charger, and the others are carried by the saw.Replace the battery in the field because the battery is depleted or overheated.When current is drawn from a lithium-ion battery, heat is generated; the harder and longer the saw is, the hotter the battery will get until a safety circuit in the battery shuts it down.Batteries from both manufacturers have lights that indicate the amount of power available.When the light starts flashing, the battery is overheated.Ordered the largest battery from the manufacturer for the saw to increase run time and reduce heat generation.
Following the evaluation phase, the department developed and delivered a train-the-trainer program for medical rescue companies to learn how to use their newly released saws most effectively.Medical responders will then train fire company personnel in cutting techniques and the capabilities and limitations of the saw.
The crew learned that battery-powered dicing saws didn’t have the power and torque they were used to using pneumatic saws.One manufacturer’s saw had a load indicator light, and when the saw fell into a cut, the revolutions per minute (rpm) had dropped to the point where the saw was no longer effective and the battery was in danger of overheating.Operators are taught to listen to the saw.If the rpm drops significantly or the blade starts to get stuck in the cut, reduce the pressure on the saw and reduce the speed at which the operator pulls the saw through the cut.
Additionally, operators are taught to size the forcible entry target to determine the minimum number of successful or most efficient cuts.Instead of trying to cut large openings in overhead and swing doors, use a battery powered saw to cut small “surgical” openings to reach and release locks and latches.For example, most commercial overhead sectional doors in South Florida are secured by sliding latches attached to the inside of the bottom second section.So make a cut in the door’s sheet metal skin that’s large enough for you to reach in and release the latch.The limited cutting depth of the saw (only 3.5 inches) was not an issue, as the operator avoided cutting any heavy reinforcements.
To cut a deadbolt on a door that swings out, strike an axe or a halligan’s adz between the door and the jamb to allow the blade to spin freely.When cutting vents in laminated glass, make three-sided cuts on the top and sides of the opening, and pull the cut into the building.
In Photo 11, a lock cylinder is cut from the center of a solid steel door.The saw easily cuts the steel rods that extend from the top, bottom, and sides of the door.
In photo 12, the battery-powered saw quickly cuts the head of the carriage bolt forced into the pillar.Due to its light weight, the saw is ideal for forcing access to building interiors, such as cutting sturdy padlocks securing stairwell roof doors.
Since MDFR acquired lithium-ion battery-powered saws, crews have used them effectively in technical rescue operations, including cutting rebar in concrete destruction operations, cutting mechanical parts in mechanical trapping operations, and cutting free patients in puncture rescues .
The tool industry has responded to the success of these saws in the construction and consumer tool markets.MDFR had two manufacturers to choose from in 2019; it now has at least five construction-grade, battery-powered dicing saws.Fire departments must evaluate all aspects of a given saw before choosing a specific brand.Selection criteria include performance, depth of cut, durability, battery life, battery cost and availability, and manufacturer support.
Overhead door struts are ideal for teaching scrap overhead rolling, slatted curtains, and cutting techniques for sectional garage doors.In photo 13, the prop is used to practice cutting techniques on a home overhead sectional door.In photo 14, Miguel built a heavy duty steel frame and fastened it to the track of the overhead roller shutters of the training facility.A sloping plate secured with ratchet straps supports an opening cut into an abandoned overhead roller shutter door that rests against the frame.
BILL GUSTIN is a 48-year fire service veteran and captain of the Miami-Dade (FL) Fire and Rescue Team.He began his career in the fire service in the Chicago area and was the lead instructor for his department’s officer development program.He teaches tactical and corporate officer training courses throughout North America.He is a technical editor and advisory board member for Fire Engineering and FDIC International.
ENRIQUE PEREA is the captain and 26-year veteran of Miami-Dade (FL) Fire Rescue, leading the technical rescue program.He is a Technical Rescue Technician, Hazmat Technician, and Heavy Equipment and Rigging Specialist for the USAR FL-TF1.Perea teaches all aspects of special operations for various agencies and is the head coach of the IAFF.He holds a bachelor’s degree in civil engineering and is pursuing a master’s degree in structural engineering.
Bill Gustin will present “Operations for Newly Promoted Corporate Officers” Monday, April 25, 1:30-5:30 pm and Wednesday, April 27, 3:30-5:15 pm, at the FDIC in Indianapolis at the International 2022 conference.
Post time: May-24-2022