Fire Rescue Tools - Cutting Saw

In the rescue and extinguishing process, special materials are often required to be cut, but rapid, safe and successful cutting depends on the use of an appropriate cutting saw.

Earthquakes, tsunami, hurricanes, typhoons, tornadoes, floods, building collapses, terrorist attacks, military operations, building fires, car accidents ( buildings, trees, cars, trucks, buses, trains, airplanes, heavy equipment ) can be listed The list is innumerable. But they all have one thing in common: They need to be broken when searching for trapped people, implementing rescue operations, forced entry, ventilation, extinguishing, or taking action across a certain area. Therefore, this article focuses on two kinds of cutting saws : the chain saw ( see Figure 1) and the circular saw ( see Figure 2) . Circular saws are also commonly referred to as disk saws, cross-cut saws, cutting saws, or motorized cutters.

Figure 1 Fuschal 450e power chain saw

Figure 2 Fuswa K970 circular saw

 

Safety, speed, ease of use, and versatility are critical factors not only for the operator of the cutting saw, but also for the trapped and nearby rescue workers. Chain saws and circular saws have exposed cutting member - the cutting blade on the cutting chain and chain saw a circular saw (FIG. 3). The saws on both saws are very sharp and rotate at high speeds, so care should be taken when handling them. Some manufacturers provide protective devices for cutting saws that can cover chains and saw blades. This protects the operator and ensures that the depth of cut is set at a predetermined depth - without cutting through the building components and weakening the objects being cut - to protect Trapped persons are very useful to avoid accidental contact with chains and blades.

Figure 3 cutting blade

A circular saw equipped with a universal vacuum calcined diamond saw blade can cut vertically any material encountered in rescue or fire. However, because the cutting blade is a disk, its cutting depth is limited. The 356 mm diameter blade has a depth of cut of only 127 mm . However, the chain saw can cut the length of the entire chain, so the 510 mm chain saw can be cut to a depth of 510 mm . The chain made of carbide inserts - the carbide alloy chain - can be broken to remove toughness iron and the vast majority of materials other than concrete. Chains made of diamond can be used to cut reinforced concrete on special chainsaws with special functions, including chain saws that use water lubrication instead of oil lubrication.

You read it correctly, the chainsaw can cut concrete ! Although chain saws equipped with carbide can cut thin metal sheets, chainsaws equipped with diamond chains can cut reinforced concrete, but none of them can cut metal. Therefore, a well-equipped fire brigade or rescue team is required to carry a variety of cutting saws to ensure that they can cut all the materials encountered in the fire or rescue scene.

Chain saws and circular saws are not new to fire protection. Circular saws have been used for 40 years; there is documentation that the use of chainsaws in firefighting began in 1953 . The popular circular saws used in firefighting initially used abrasive saw blades, later carbide alloy saw blades, and now diamond saw blades. It took a long time for the chainsaw to become a practical fire and rescue tool, because when cutting non-wood materials, the chain quickly became less sharp. Until 1966 , Martin Brad, a fire-fighting captain in Los Angeles, California, proposed that the method of adding a carbide alloy to a chain saw cutter be patented and the chain saw be recognized in firefighting.

However, in 1985 , another California firefighter, Tom Lutz, developed a safer way to add carbide to chain saw chain cutters and improved the chain saw engine to make it faster. The chain is driven and can be operated under hot smoke conditions so that the use of chain saws is eventually promoted in firefighting. In 1993 , Luz continued to develop and obtain a patent for the design of a special alloy carbide cutter-bullet chain. The chain maintains the good performance required for the fire rescue chain saw to break. Both chain saws and circular saws can be driven by gasoline-driven two-stroke engines, hydraulic motors, electric motors, and pneumatic motors. In the past 40 years, the experience of using chainsaws and circular saws proved that the use of gasoline and hydraulically driven cutting saws is the first choice for fire rescue tools. Gasoline-driven cutting saws are the most popular, accounting for 90 % of currently used chainsaws and circular saws . Hydraulically driven cutting saws make up the majority of the remaining 10 %, with the rest being sporadic electric and pneumatic cutting saws.

Gasoline powered saw blades are the most widely used due to their rapid deployment, ease of use, and unrestricted versatility. However, gasoline-powered saw blades sound loud enough to reach 104 decibels (dB) and produce harmful exhaust gases, so they should be considered when used in confined areas, especially if there are no ventilation equipment. Hydraulically driven cutting saws are a good choice for confined spaces, and the number of cuts and material types should also be considered. In general, hydraulic cutting saws (Figure 4) are more suitable for continuous cutting.

Figure 4 hydraulic cutting saw

So, what kind of cutting saw is used to determine what factors ? Let us divide this question into two categories: firefighting and rescue.

1 Fire extinguishing

Wildfires, forest fires, jungle fires, and other wild/woodland fires are tangled together or occur separately. There is no doubt that a chain saw is needed.

In fact, the most suitable cutting saw is a gasoline-driven conventional chain saw with a conventional ( non-carbonized alloy ) wood cutting chain. Cutting trees is a design feature of chainsaws. Despite the possibility of high temperatures and smoke, the surrounding air is usually sufficient to support the operation of conventional chain saws without air intake restrictions and without running conventional wood cutting chains.

There are many producers of conventional chain saws, and high-quality chainsaws are also well-suited to work. But this is determined by the specifications, and more properly, it is determined by the power. For example, for the area of ​​responsibility under your jurisdiction, the 510 mm depth of cut is the size you need. There is now a chain saw with a 510 mm guide rod driven by a 45 em3 engine , and a chain saw with a 510 mm guide rod driven by a 70 cm ' engine . Power, weight, and cost are issues that need to be considered. Therefore, the technical parameters should be very clear, so as to ensure that your chain saw has enough power to complete the task.

The building fire extinguishes a series of different situations. The purpose of using a dicing saw in building fire extinguishing is to cut the air vents, force entry into the building, open up the area to check the spread of fire, carefully inspect, and provide quick intervention. The operating environment of a cutting saw in a building fire can be very hot and full of smoke, and the smoke from building fires includes unburned gases. These gases, which are lighter than air, easily float through the air filter of conventional cutting saws.

In the event of a building fire ( and the breaking of concrete during the rescue ) , water and steam will also permeate the conventional filter element. Keep in mind that according to design requirements, conventional chainsaws and circular saws should be operated in a fresh air environment. The air filters on these conventional cutting saws do not work in high temperature and smoke-filled environments. Chain saws require stronger, more functional carbide chains to cut through the many different building materials encountered. Building fire suppression is a value added feature such as the need for large multi-stage external air filters, guards/depth gauges and special carbide alloy chains, carbide alloys, and diamond disc saw blades.

2 rescue operations

Rescue cutting involves a variety of other cutting needs, from the multiple materials that collapsed buildings, dumped trees, deformed vehicles and aircraft to reinforced concrete. Imagine all the different types of materials that may be encountered in the collapse of a building. Causes of collapse can also cause differences in the need for cutting. For example, the collapse caused by an earthquake includes the need to cut construction materials such as wood, metal, plastic, sheet metal, concrete, wires, pipes, and so on. However, in the earthquake accompanying the tsunami, all of these were covered by mud, stones and other debris.

In the Pacific Northwest of the United States, there are several interstates that cross the mountain pass and often experience extreme winter snowstorms. These roads are the main transportation routes for transporting various commodities. Some of these trailer trucks are as long as three trailers, weighing more than 45 000 kg , frozen roads, and the deep, unfathomable canyons below, which pose great challenges to rescue.

Imagine a bucket truck carrying 32 000 kg of frozen meat. The truck slid to the side of the road, over the edge of the rocky cliff, and fell into the canyon below 50 m . Trailers loaded with frozen meat crush the truck's cab and trap the two people in the car. The emergency rescue vehicle could not access the vehicle that was crashed due to no way. Due to the impact caused by the snowstorm, the nearest cranes and tractors were also outside the 3 h away. The hydraulic cutters and extension mills decentralized to the wreckage of the truck could not handle a large number of vehicles. s material. A rescue chain saw with a carbide-alloy bullet chain and a circular saw with a diamond saw blade can be used here . Materials that need to be cut include metals, aluminum, plastics, fiberglass, and frozen meat. A circular saw can cut all the metal. Chain saws can be used to cut aluminum trailer siding, plastics, fiberglass bottles and frozen meats .

Fire fighting and rescue technologies continue to innovate and develop. We all tend to use new technologies because we are always looking for better ways. But sometimes new technologies and innovations put existing tools into new applications.

The information in this article comes from the Internet and was reorganized and edited by China Rescue Equipment Network.