Rescue Squad Modules 3-7, 12 PDF

"Rescue Squad" Modules 3-7, 12  Pneumatic Tools Introduction Pneumatics refers to technology dealing with the application of pressurized gas (potential energy) to produce mechanical motion (kinetic energy). Pneumatic systems used in the fire/rescue service primarily...

"Rescue Squad" Modules 3-7, 12  Pneumatic Tools Introduction Pneumatics refers to technology dealing with the application of pressurized gas (potential energy) to produce mechanical motion (kinetic energy). Pneumatic systems used in the fire/rescue service primarily use compressed gas as the source of power. There are a variety of pneumatic tools used in the fire/rescue service, each with a specific function. While some of these tools were developed specifically for rescue, many are simply borrowed from other industries, such as the automotive repair industry. All of the components of a pneumatic tool setup will be discussed in this module, starting with the air source and working downstream to the actual tool. Air Sources The key component to any pneumatic tool or airbag operation is compressed air. Compressed air can be obtained from a variety of sources on a rescue incident: Air Compressors Air compressors provide an unlimited supply of air. The most common type is the positive- displacement compressor that uses a reciprocating piston. (Other types that utilize impellers or rotary screws do exist.) The piston air compressor has components similar to an internal combustion engine: a crankshaft, connecting rod and piston, cylinder and a valve head. Typical compressors come in 1- or 2- cylinder versions and can be single- or two- stage. The compressor supplies a storage tank. When needed, air is drawn from the tank and the compressor replenishes it. Air compressors stop supplying the storage tank when pressure inside the tank reaches a specified limit. When air is consumed and the pressure in the storage tank drops below a certain level, the compressor starts up again. MCFRS Driver Certification Program Page 1 of 15 Rescue Squad – Module 3  Pneumatic Tools & Equipment Rev. 12/1/14 Air Compressors (continued) Air compressors can be permanently mounted in a structure or on apparatus or they can be portable. They can be driven by an electric motor or an internal combustion engine, either directly or via a PTO. The source of the compressor’s power isn’t as important as the compressor’s capacities for air production. Two important specs to know about a compressor are its ratings for volume and pressure output. Volume output for air compressors is expressed in cubic feet per minute (cfm). The cfm rating of the compressor will dictate the quantity and type of pneumatic tools it can adequately supply. The pressure rating of the compressor is also a factor to consider. A higher pressure in the storage tank means a larger quantity of air. Larger quantities of air can support tools with higher air consumption rates. The quality of the air coming out of an air compressor is vital to tool and equipment performance and service life. Ambient air contains moisture. When air is compressed, its temperature increases as well as its ability to hold water vapor. When air travels away from the compressor to the storage tank, its temperature decreases. When the temperature decreases, the water vapor condenses and builds up in the storage tank, air lines, and tools. The water can corrode air tanks and damage internal components of air tools and equipment. Some air compressors use oil to cool and lubricate internal components. Some of this oil can leave the compressor with the air and make its way to tools and equipment. Incorporating air treatment devices like air dryers and filters are a necessity for prolonging the service life of a pneumatic system. Cascade Systems Another air source is a cascade system. A cascade system is a group of high-pressure cylinders (two or more) connected together and fed by an air compressor. The cascade systems on apparatus are usually filled from an external compressor at a fire station. Air in a cascade system moves from the point of higher air concentration to the point of lower concentration. The cylinder with the higher air pressure will force air into the cylinder with the lower pressure until the pressures in both cylinders equalize. Since all cylinders in a cascade system are interconnected, air can be drawn from only one cylinder or a combination of any or all cylinders. However, pulling from only one cylinder at a time will help maintain higher pressures in the remaining cylinders. MCFRS Driver Certification Program Page 2 of 15 Rescue Squad – Module 3  Pneumatic Tools & Equipment Rev. 12/1/14 Cascade System (continued) Cascade systems are most often used in the fire service to fill SCBA cylinders. These systems are filled with air compressors that meet OSHA and NFPA respiratory standards for breathing air. Therefore, air supplied with a SCBA cascade system will not contain the level of moisture and contaminants found in industrial air sources. Self-Contained Breathing Apparatus (SCBA) Cylinders Self-Contained Breathing Apparatus cylinders (SCBA) are a good portable air source when operating pneumatic tools and air bags. The caveat to their portability is the limitations on air volume. It is important to know cylinder capacities and quantities available during a rescue operation. Scott 4500psi SCBA Cylinder Capacities 30-Minute 45 standard cubic feet 45-Minute 65 standard cubic feet 60-Minute 87 standard cubic feet **Scott Carbon-Wrapped, CGA Threaded Cylinders at 4500 psi – www.scottsafety.com Mobile Air Carts The air cart is a commercially made device that holds high-pressure cylinders. Two manufacturers of fire/rescue specific air carts are Scott Safety and Air Systems International. Both of these variations contain two SCBA cylinders. They are connected to a manifold and provide a number of air outlets. The air cart is designed to operate off of one cylinder at a time. It will provide an audible alarm when the pressure in the cylinder being used reaches a level of approximately 500 psi. At that point, the remaining cylinder can be opened, and the air cart will transition to the higher pressure. The cylinders are set up in an arrangement that allows for the replacement of one cylinder while using the other. This arrangement allows for an uninterrupted air supply. They also contain a high-pressure inlet that allows hookup to an external air source such as a Mobile Air Unit. MCFRS Driver Certification Program Page 3 of 15 Rescue Squad – Module 3  Pneumatic Tools & Equipment Rev. 12/1/14 Air Brake Systems The air brake system on commercial trucks can be used to supply air for pneumatic tools. The engine air compressor produces air for the air brakes and other components. These air systems generally operate around 120 psi. Tractor trailers have an air connection between the tractor and the trailer in order to provide an air supply for the rear brakes. There will be two hoses, one red and the other blue. The hoses are connected via a glad hands coupling. The blue hose is used for normal braking operation and it is referred to as service airline. The red hose is the emergency airline. In the event that the red airline becomes disconnected (such as when the trailer disconnects from the tractor), the trailer brakes are automatically applied. On some trailers, the same type of connection can be found at the rear end of the trailer. The service and emergency airlines are supplied by the engine air compressor on the tractor. An adapter can be used to make the connection to the glad hands coupling on the rear of the tractor, providing an air supply for pneumatic tools and equipment. Fire Apparatus Auxiliary Air Fire apparatus will typically have air connection(s) for auxiliary air hookup. These connections are supplied by the air reservoirs that are part of the vehicles air system. Just like the commercial air brake systems previously discussed, fire apparatus air systems can provide approximately 120 psi of useable air. Tire Fill Adapter With the correct type of adapters, air can be drawn from the tires of vehicles on the scene. Generally, fire apparatus tires have an inflation pressure ranging from 110 to 120 psi while passenger cars may only have 25 to 35 psi to offer. Consideration should be given to the volume of air necessary to accomplish a task when utilizing this air source. MCFRS Driver Certification Program Page 4 of 15 Rescue Squad – Module 3  Pneumatic Tools & Equipment Rev. 12/1/14 Air Regulators Air sources such as SCBA cylinders, air carts, cascade systems and some air compressors produce high pressure air (pressures in SCBA cylinders can be as high as 5500 psi). However, the majority of the pneumatic tools and airbags (even “high pressure” airbags) used in the fire/rescue service operate below 150 psi. Exceeding the normal operating pressures of pneumatic equipment can not only be a waste of valuable air supply, but also potentially damaging to the equipment. Therefore, a pressure-reducing device (pressure regulator) is needed to provide useable low pressure air. Components and Operation Pressure regulators are comprised of three functional elements:  A pressure reducing or restrictive element (generally a poppet valve)  A sensing element (generally a diaphragm or piston)  A reference force element (generally a spring) At a basic level, an air regulators work like this: 1. High pressure air flows into the high pressure chamber of the regulator 2. The adjustment screw is tightened, which compresses the spring 3. The spring compression produces force that pushes down on the diaphragm/piston 4. The force on diaphragm/piston pushes down on the valve stem, opening the poppet valve 5. Air is able to enter the low pressure chamber of the regulator 6. The regulated air creates a force that opposes the diaphragm/piston and closes the poppet valve. 7. Increasing the force in the spring will result in an increase in opposing force from the air in the low pressure chamber and thus an increase in outlet air pressure. Decreasing the force in the spring will have the opposite effect MCFRS Driver Certification Program Page 5 of 15 Rescue Squad – Module 3  Pneumatic Tools & Equipment Rev. 12/1/14 Diaphragm regulators are generally more sensitive to pressure changes and react more quickly. They are used for increased accuracy and low pressure applications. Piston regulators are more rugged and used when higher outlet pressures are required and are not held to as tight a tolerance. Both types are typically equipped with gauges to read both inlet and outlet pressures. Diaphragm Regulator Piston Regulator Hurst PermaSet Regulator A third type of regulator that is sometimes used in the fire/rescue service is the permanently-set or preset regulator. This regulator has a sensing element that is already set and is not adjusted during use. The outlet pressure on this style of regulator is set at the factory, generally at maximum of 175 psi. Hurst and Paratech utilize this style of regulator with some of their airbag controller setups. Maintenance and Use General operating practices are outlined in this section. Manufacturer’s recommended operating procedures should always be followed when using a regulator. Prior to connecting a regulator to an air source, perform the following:  Check the regulator for any damage  Ensure that inlet and outlet pressure gauges are reading “zero”; the regulator will still function with incorrect gauge readings, but a faulty outlet pressure gauge prevents accurate outlet pressure settings which could damage the equipment connected to the regulator  Check the high pressure connection for the presence of an O-ring; replace if necessary  If adjustable, ensure that the adjustment knob/handle is turned fully counterclockwise to lower outlet pressure and close the poppet valve, preventing the flow of air through the regulator. If the poppet valve is not closed when the high pressure source is opened, air can flow through the regulator, possibly at pressures too high for downstream equipment MCFRS Driver Certification Program Page 6 of 15 Rescue Squad – Module 3  Pneumatic Tools & Equipment Rev. 12/1/14 Maintenance and Use (continued) Once the regulator is connected to the air source, the operator should:  Check for air leaks at the inlet (high pressure) coupling; if leaks exist, shut down the air source, check for O-ring issues and attempt to reconnect  Connect the outlet (low pressure) coupling to an appropriate air hose  If equipped, open the delivery shutoff valve on the regulator – this will allow air to flow through the regulator outlet downstream to the equipment  Slowly turn the adjustment knob/handle clockwise to increase the outlet pressure to the correct setting; it may be necessary to fine tune the pressure adjustment once air tool operation begins and air is flowing through the regulator (Permanently set or preset regulators will automatically provide the set working pressure.) Upon completion of the air tool/equipment operation, shut down the regulator as follows:  Turn off the air supply  Bleed the pressure from both the high pressure and low pressure sides of the regulator. Some regulators have an exhaust port that will slowly bleed pressure. Others require manual bleeding.  Once both pressure gauges are at “zero”, return the adjustment knob/handle back to the fully counterclockwise position.  Disconnect the air hose from the outlet coupling and the air source from the regulator inlet. Regulators should be stored in a clean, dry environment. Gauges are susceptible to damage so appropriate precautions should be taken to protect them. Any damage to the regulator or gauges and/or faulty operation should place the regulator out-of-service for repairs or replacement. MCFRS Driver Certification Program Page 7 of 15 Rescue Squad – Module 3  Pneumatic Tools & Equipment Rev. 12/1/14 Air Hoses Air hoses are a critical component of any pneumatic tool and airbag setup. They are the connecting medium between the equipment and can have a direct effect on air volume and pressure. Air hoses can be constructed of various types of rubber or plastic and may contain a form of fabric reinforcement. The hose should be marked with a service or working pressure; never exceed the manufacturer’s recommended operating pressures. Hose lengths can be short (around 16 feet for many airbag systems) or as long as 200 feet (common length for apparatus hose reels). Much like fire hose, air hose creates friction losses. The magnitude of these losses depends on hose diameter and length as well as air flow. The Association for Rubber Products Manufacturers (ARPM) provides some tabulated data in their “Hose Handbook” referencing friction loss in air hose. Some of this data is shown in the tables below: Friction Loss in Air Hose (psi) per 100-foot length Gauge Pressure at Cubic Feet Free Air Per Minute (SCFM) Hose I.D. (inch) Line (psi) 3.0 5.0 10.0 100 3.73 10.36 - 1/4 150 2.60 7.21 - 200 1.99 5.53 22.14 100 0.44 1.23 4.92 3/8 150 0.31 0.86 3.42 200 0.24 0.66 2.63 From ARPM Hose Handbook, 8th Edition – Table 11-4A Friction Loss for Pulsating Air through Hose (psi) per 100-foot length Gauge Pressure at Flow of Free Air (SCFM) Hose I.D. (inch) Line (psi) 30 40 50 50 10.0 20.2 36.2 1/2 80 5.6 12.0 21.6 100 4.6 9.6 16.8 From ARPM Hose Handbook, 8th Edition – Table 11-4B **The above tables refer to “Free Air” at atmospheric pressure (14.7 psi) and 80°F **The pressure drops listed assume hose with smooth I.D. tubing and full-flow couplings. Greater pressure drops will occur in hose with rough I.D. tubing or restrictions at couplings/fittings. MCFRS Driver Certification Program Page 8 of 15 Rescue Squad – Module 3  Pneumatic Tools & Equipment Rev. 12/1/14 The majority of pneumatic tools and equipment used in the fire service will require a minimum air hose diameter of 3/8”. Smaller ¼” air hoses (commonly found on small home air compressors) will not meet volume requirements and can result in inefficient tool operation or even damage. 1/4” Recoil Air Hose 3/8” Air Hose MCFRS Driver Certification Program Page 9 of 15 Rescue Squad – Module 3  Pneumatic Tools & Equipment Rev. 12/1/14 Pneumatic Tools As mentioned at the beginning of the module, the majority of pneumatic tools used in rescue are actually designed for the automotive repair industry. However, there are some tools designed specifically for fire/rescue applications. Types of Pneumatic Tools Impact Wrench Pneumatic impact wrenches provide high torque output. In addition to rotation, impact wrenches apply a hammering force. They are commonly used in automotive, construction, and assembly industries. Impact wrenches come in drive sizes similar to ratchet sets. Common automotive drive sizes are ¼”, 3/8”, ½”, ¾” and 1”. For industrial applications, drive sizes can be as large as 11/2” and 21/2”. Due to the high torque of an impact wrench, regular sockets should NOT be used. Standard chrome sockets are fairly brittle and can shatter from too much vibration. Impact sockets are made from chrome-molybdenum alloy steel, which is a softer more malleable material. These sockets are designed to absorb the high impact forces from an impact wrench and deform instead of shattering like standard sockets. Torque ratings can range considerably depending on the size of the impact wrench and its application. Working torque ranges can be anywhere from 25 to 350 lb-ft. Maximum torques can exceed 1000 lb- ft. Air consumption also varies with size and application. For automotive applications, average consumption rates can be 5-10 cfm. Under load, these torque wrenches may use in excess of 20 cfm. For industrial and manufacturing applications, air consumption rates can dramatically increase – some as high as 40 cfm. Air Ratchet Air ratchets apply far less torque and operate at lower RPMs than impact wrenches. They are designed to increase efficiency and save time in applications where standard ratchets would be used. MCFRS Driver Certification Program Page 10 of 15 Rescue Squad – Module 3  Pneumatic Tools & Equipment Rev. 12/1/14 Air Ratchet (continued) Standard drive sizes for air ratchets are ¼”, 3/8” and ½”. Due to the lower torque ratings, impact sockets are not required. Torque ratings can range from 5 to 75 lb-ft. Average air consumption rates for air ratchets are around 4-5 cfm. Air Hammers The air hammer (or “air chisel” as it’s sometimes called) is one of the more commonly used pneumatic tools in rescue. In fact, a larger version of an air hammer, which will be discussed later in this module, was developed specifically for fire/rescue applications. As the name suggests, air hammers create a hammering action through the use of a piston. The working end of the air hammer is the chisel. Chisels are used to pierce and cut metal. There are numerous types of chisel designs, each with different specialties. Some Common Types of Chisels (from left to right)  Tailpipe/muffler cutter  Straight/flat chisel  Cutting chisel  Edging tool  Tapered punch Chisels are held in the air hammer with a retainer. There are two types of retainers: coil spring and quick change. Most air hammers can be fitted with either type, but the quick change retainer is preferred for fire/rescue work. Quick change retainers are faster and easier to use and also minimize the risk of a chisel dislodging from the hammer during use. Coil Spring Retainer Air consumption rates for air hammers are around 2-3 cfm, with some peaking between 10-15 cfm under load. Quick Change Retainer MCFRS Driver Certification Program Page 11 of 15 Rescue Squad – Module 3  Pneumatic Tools & Equipment Rev. 12/1/14 Cut-off Tool The pneumatic cut-off tool is simply a small version of the gasoline-powered Partner and Husqvarna rotary cut-off saws carried on almost all truck companies and rescue squads. An abrasive cutting disc is attached to an arbor rotating at high speed (20,000+ RPMs). Most pneumatic cut-off tools use a 27/8” cutting wheel. It is important to only used appropriately-sized cutting wheels and ensure that they are securely fastened to the arbor. Blade guards are standard on cut-off tools and they should be used. If cutting wheels are damaged in any way or worn to the point where they will no longer effectively cut, they should be replaced. Air consumption rates are around 5-10 cfm, depending on the specific cutter. Air Shear Air shears are another type a pneumatic cutting tool. They are capable of cutting plastics and all types of aluminum, tin and up to 18-20 gauge steel. Unlike the cut-off tool’s consumable cutting wheels, the air shear’s blades are part of the tool and should not need replaced under normal use. Air shears consume 4-5 cfm. Air Reciprocating Saw The air reciprocating saw is a smaller version of electric and battery-powered reciprocating saws found on almost all fire apparatus. The bi-metal blades can cut a variety of plastics and thin metals. Standard ½” shank air reciprocating saw blades come in 14-tooth up to 32- tooth construction for coarse to fine cutting. Common air consumption rates are 1-2 cfm during normal use. MCFRS Driver Certification Program Page 12 of 15 Rescue Squad – Module 3  Pneumatic Tools & Equipment Rev. 12/1/14 Maintenance and Use Air pressure is an important component of proper tool operation. The pneumatic tools mentioned in this module typically have manufacturer-recommended operating pressures of 90 psi. The tools will operate at pressures above 90 psi, which will increase torque and possibly improve performance. However, in the long run, this will reduce the life expectancy of the tool. Operating pressures less than 90 psi will result in tool inefficiency and decreased performance. One common mistake made by operators is to set the air regulator at the tool operating pressure and never give it a second thought. However, by the time the air reaches the actual tool, the pressure may be significantly reduced. Several factors (such as air leaks, hose configurations and lengths, the number and types of couplings, etc.) can reduce air pressure. So if the tool is not functioning as it should, this could be one possible cause. All of the pneumatic tools discussed in this module contain many internal moving parts. To maintain peak efficiency and improve tool life expectancy, these internal components must be clean and well lubricated. Air tool oil provides the necessary lubrication and rust prevention for the internal moving parts. Some pneumatic tools are equipped with in-line oilers that introduce oil into the tool air during normal use. Tools without oilers must be manually lubricated on a regular basis. In addition, many pneumatic tools have grease fittings that require periodic service. It is important to follow manufacturer’s recommendations for the types of lubricants and their proper use. In-Line Oiler Hoses and couplings can be a source of water, dirt, grit, and other contaminants that will cause damage and excessive wear to internal tool components. Be sure to inspect all couplings before connecting them. If necessary, clean and dry them before use. Store all pneumatic equipment in a clean, dry environment. Regular preventive maintenance will help ensure the tools perform as they should when needed. MCFRS Driver Certification Program Page 13 of 15 Rescue Squad – Module 3  Pneumatic Tools & Equipment Rev. 12/1/14 Paratech Airgun and Pakhammer The Paratech Airgun and Pakhammer are two pneumatic impact tools designed specifically for fire/rescue applications. The two are used for forcible entry (piercing, cutting, and breaking) as well as medium duty breaching and breaking of masonry walls. They utilize a piston much like a traditional air hammer. However, Paratech designed the Airgun and Pakhammer with air conservation in mind. Both tools only use air on the power stroke; an integrated spring retracts the piston on the return stroke. Airgun and Pakhammer operating pressures range from 40 up to 200 psi, depending on the application. However, increasing operating pressures will increase air consumption. For the Airgun, air consumption is rated at 5 SCFM @ 40 psi but 15 SCFM @ 200 psi. The larger Pakhammer consumes air at a rate of 8.5 SCMF @ 40 psi and 19 SCMF @ 200 psi. One of the large benefits of the Airgun and Pakhammer over traditional air hammers is power output. Both tools are designed for rescue and therefore provide increased cutting/breaching/breaking force. The Airgun is rated for 71 ft-lbs. @ 50 psi up to 369 ft- lbs. at 200 psi. The Pakhammer is rated for 158 ft-lbs. @ 50 psi up to 876 ft-lbs. @ 200 psi. The Airgun and Pakhammer can be used with a wide variety of bits on a broad range of materials. The user manuals for each tool list recommended tool bits and operating pressures for specific applications, whether it’s cutting automobile posts, breaking concrete, or shattering castings. MCFRS Driver Certification Program Page 14 of 15 Rescue Squad – Module 3  Pneumatic Tools & Equipment Rev. 12/1/14 Routine maintenance of the Airgun and Pakhammer will keep them operating at peak efficiency. The surface of the tools should be kept clean of dirt, grease, etc. If the tool has been operated in a dusty, abrasive environment or if the tool bit retainer assembly is subjected to a damp or wet material, Paratech recommends cleaning the retainer assembly with dry cleaning solvent and lubricating with air tool oil afterwards. Both tools are fitted with an in-line oiler. As air passes through the oiler, a controlled volume of lubrication is picked up with the air to maintain continuous fog lubrication of the internal components. The oil level should be periodically checked. If empty, fill the oiler housing until half-full with Marvel® Air Tool Oil. MCFRS Driver Certification Program Page 15 of 15 Rescue Squad – Module 3  Pneumatic Lifting Devices – Air Bags Introduction There are several different tools carried on Truck companies and Rescue Squads used for lifting. One such piece of equipment is the air bag. Air lifting bags are capable of lifting heavy loads with relative ease and efficiency. Some of the largest bags are capable of lifting over 90 U.S. tons. Proper training and education are paramount to a successful lifting bag operation. Operators must fully understand the principles behind bag design and operation as well as the necessary safety precautions. Just a few of the applications that air lifting bags can used for include:  Lifting and up-righting overturned vehicles  Person(s) pinned under a heavy object (e.g. tractor trailer, train, vehicle, etc.)  Rescue/recovery after collapses  Forcing solid objects apart  Providing a seal for leaking pipes drums or other cylindrical containers Some of the advantages of air bags include:  Long life  Fairly lightweight  Low insertion heights  Quick and easy to set up  Relatively low operating pressures  Ability to lift on a slope  Provide a smooth, quiet lift  Provide an anti-slip surface  Flexible  Corrosion resistant  Fairly simple to use Air lifting bags are categorized into three different types based on their working pressures: 1. High Pressure 2. Medium Pressure 3. Low Pressure Each type has unique features and capabilities. However, all three share a similar equipment cache for operating. Each type of bag and the associated equipment will be discussed in this module. MCFRS Driver Certification Program Page 1 of 13 Rescue Squad – Module 4  Pneumatic Lifting Devices – Airbags Rev. 12/1/14 Equipment Air Source and Pressure Regulator Several different types of air sources were covered in the “Pneumatic Tools and Equipment” module. While most of those air sources are capable of providing air for an airbag operation, some are preferred over others. Air from industrial and vehicle-mounted compressors often use oil to lubricate internal compressor components. In addition, these air sources contain moisture from ambient air. While filters and dryers are often incorporated into the compressor design, they do not guarantee the absence of contaminants. Some of the synthetic oils used in modern air compressors have been shown to damage and degrade interior components of air bag systems, specifically O-rings. Conversely, breathing air sources (e.g. SCBA cylinders) are filled with air that meets stringent OSHA and NFPA respiratory standards. The compressors that supply breathing air are equipped with advanced moisture separators and purification chambers that eliminate the contaminant and moisture issues of industrial compressors. For this reason, breathing air is the preferred source for air bag evolutions. As with pneumatic tools, air must often be taken from a high pressure source like an SCBA cylinder and brought down to a proper operating pressure for air bags. The pressure regulators described in the “Pneumatic Tools and Equipment” module are used to perform this task. The working pressures for air bag lifting systems range from 7 psi up to 145 psi. **Note: Another common unit of pressure used with airbags is "bar”. 1 bar = 100 kPa = 14.5 psi. Do not confuse the unit of bar with Standard Atmospheric Pressure (atm), which is 14.7 psi or 1.01325 bar. MCFRS Driver Certification Program Page 2 of 13 Rescue Squad – Module 4  Pneumatic Lifting Devices – Airbags Rev. 12/1/14 Controller The controller is the device which allows air to flow in and out of the bag. It contains the gauges that allow the monitoring of the air pressure inside the bag. It also contains two internal relief valves to prevent over pressurization of the bags. Most high pressure air bag systems have a maximum working pressure of 8 bar/116 psi or 10 bar/145 psi. Whenever the pressure inside the bag exceeds this mark, it will be indicated on the gauges on the controller and the internal relief valve will vent (allow the extra pressure to escape). It will continue to vent until the correct pressure is reached. This is called relief valve reset and it should occur at the maximum working pressure as indicated on the controller by a red marking. Controllers are outfitted with either “deadman” controls or quarter turn valves. Deadman controls return to a neutral position when they are released preventing accidental over pressurization. Quarter turn valves act like an on/off switch but they must be manually set to the desired position (much like a gated wye). Attention must be paid not to keep the quarter turn valve in the open position after the desired lift has been achieved. Connections Controllers provide a coupling, typically with a female end, to connect to the air supply. At this point in the connection, the air pressure should have already been reduced by the air regulator to the working pressure of the lifting system. If this is not true and air is applied to the controller at high pressure from the air source, severe damage can occur to the controller. Some couplings may be quarter turn, which require that you turn and push the collar back before you can attach to the other part of the fitting. Others may be quick-connect which will always readily go together. The type of couplings will vary by manufacturer. MCFRS Driver Certification Program Page 3 of 13 Rescue Squad – Module 4  Pneumatic Lifting Devices – Airbags Rev. 12/1/14 The set of couplings located on the front of the controller are most likely proprietary by manufacturer in order to avoid mixing components from one brand with another. These connections are used to connect the air hoses going from the controller to the air bags. Some manufacturers make these couplings in such a way that you cannot connect the hoses directly from the air supply to the bags without using a controller, thus interposing a relief valve which prevents over pressurization of the bags. These connections may also be used to add a second relief valve, usually with a shut-off, between the bag and the controller. In-Line Relief Valves Placement In-line relief valves work in the same fashion as the internal relief valves. They are considered in-line because they are located between the controller and the airbag rather than an internal component. In-line relief valves can be placed at the controller or at the airbag itself. Frequently these devices are placed at the controller to limit persons working near the load. Relief valves are usually only placed at the airbag when there is a limited number of air hoses and only one controller. By placing the relief valve at the bag, the hoses and controller can be removed and used at a different location on a different bag. Prior to disconnecting the hoses, the quarter turn valve is closed to prevent air from being lost from the bag. Some manufacturers incorporate the relief valve into the air hose so the placement of the relief valve is predetermined. Relief valve placed at the airbag Relief valves placed at the controller MCFRS Driver Certification Program Page 4 of 13 Rescue Squad – Module 4  Pneumatic Lifting Devices – Airbags Rev. 12/1/14 Operation Relief valves are preset to a specific pressure, normally the maximum working pressure of the system. Whenever the pressure inside the system exceeds this benchmark, the relief valves vent allowing the excess pressure to escape through vent holes on the valve body preventing over pressurization of the bag. When the relief valve vents, a hissing noise will be heard until the proper pressure is reached. Hoses Lengths Hoses are usually around 16, 32, and 50 feet in length, ¼” to 1 ½” in diameter (depending on type/pressure of bag), and color coded for easier identification of the bags when using more than one bag. Couplings Couplings are different from one lifting system to the other. The couplings for the high pressure system are different from the couplings for the low and medium pressure systems. In addition, the hoses from the low and medium pressure systems are different from the hoses used by the high pressure system. The low and medium pressure systems use a higher air volume therefore, their diameter is greater. Hose couplings are often manufacturer specific. This prevents a specific manufacturer’s air bag from being used with inappropriate or non-rated equipment. MCFRS Driver Certification Program Page 5 of 13 Rescue Squad – Module 4  Pneumatic Lifting Devices – Airbags Rev. 12/1/14 Air Bags High Pressure Bags Capacities and Sizes The bag is the component in direct contact with the load and is the component performing the actual lift. Air bags range in capacities from 1 to more than 90 tons and have lifting heights from 3” up to multiple feet. Bags are constructed in different shapes and sizes. Some of the smallest bags measure 5.1” x 5.5” while some of the largest bags measure 37” x 37”. High pressure airbags are anti-static, self- extinguishing, oil and ozone-resistant, have a good resistance to chemicals, cold resistant to 40°F and heat resistant to 239°F on a short term basis. High pressure airbags have a bursting pressure between 32.5 bar and 74.3 bar (471 - 1,077 psi) giving them a safety factor of 4 to 9.3 times the maximum operating pressure. Construction The bags are made of Neoprene, a family of synthetic rubbers, and are molded in a way to provide grip and slip resistance. They are reinforced with layer(s) of either steel wire (similar to steel-belted radial tire construction) or in the case of newer bags, Aramid fibers. By using Aramid fibers, such as Kevlar™, the bag becomes stronger, lighter, and more flexible than a bag made with steel wire. All capacities, operating pressures and lifting heights are permanently vulcanized to the surface of the bags so it is available for reference as needed. The nipple has a small orifice in order to allow the bag to deflate slowly. MCFRS Driver Certification Program Page 6 of 13 Rescue Squad – Module 4  Pneumatic Lifting Devices – Airbags Rev. 12/1/14 Operation Air bag capacities are determined by their surface area and operating pressure. To determine the maximum lifting capacity, the bag’s surface area is multiplied by its operating pressure. Operating pressure for high pressure air bags is either 8 bar/116 psi or 10 bar/145 psi. Surface Area (A) = Length (L) x Width (W) A = 10 inches x 10 inches A = 100 in2 (square inches) 10 inches Operating Pressure = 8 bar = 116 lbs/in2 (psi) Capacity = Surface Area x Operating Pressure Capacity = 100 in2 x 116 lbs/in2 Capacity = 11,600 lbs = 5.8 U.S. tons 10 inches High pressure air bags are rated at one inch of lift. The air bag is only capable of lifting its rated capacity if the entire surface of the bag is in contact with the object being lifted. Once air is introduced to the bag, it starts taking the shape of a pillow thus, reducing the surface contact with the object being lifted, and decreasing its capacity. Once the bag reaches its maximum height, the rated capacity is reduced by roughly 50%. Surface contact is paramount when calculating lifting capacities and when operating with air bags. The bag has lost surface contact with the ground and the object. As a result, the lifting capacity at this height is reduced As a rule of thumb, the maximum inflation height of a high pressure air bag is equal to half of the length of the shortest side of the bag. MCFRS Driver Certification Program Page 7 of 13 Rescue Squad – Module 4  Pneumatic Lifting Devices – Airbags Rev. 12/1/14 Medium pressure bags The walls or sides of the medium pressure bags are made of hermetic, Kevlar™ impregnated or nylon reinforced Neoprene. The top and bottom external surfaces are made of reinforced fabric with a gripping surface in order to reduce slippage. Some manufacturers claim that, due to the manufacturing process, the seams are the strongest part of the bag. Inside low and medium pressure air bags, running from the top to the bottom surfaces, are vertical reinforcing straps. These straps help the bags keep lateral movement to a minimum and at the same time prevent the surfaces of the bags from bulging out. Medium pressure bags are offered in a number of sizes and styles. Some have cylindrical shapes. Others are multi-cell, which is similar to three bags stacked on top of each other. Some applications for medium pressure air bags include lifting or stabilizing overturned vehicles, especially in situations dealing with thin metal walls like on tractor-trailers. They provide a large footprint for the area being lifted and minimize the possibility of punch- through or collapse of the surface being lifted/pushed. They are also used to fill voids in trench rescue operations. Medium pressure bags provide their rated capacity during the entire lift. As long as surface contact is maintained with the bag, it will lift the rated capacity. Medium pressure bags that are cylindrical in shape will reach their maximum stability at full inflation. Lifting capacities range from 3 to 13 tons. Air consumption varies from 10 to over 100 cubic feet. As with the high-pressure system, to operate the medium pressure bags you need an air source, an air pressure regulator, a controller with relief valves, and hoses. Because of the pressure difference between systems, these components are not interchangeable with the high pressure systems. Medium pressure systems are designed to operate at 1 bar/14.5 psi. They have a much higher air consumption rate than high pressure bags. For that reason, the air hoses have a larger diameter. MCFRS Driver Certification Program Page 8 of 13 Rescue Squad – Module 4  Pneumatic Lifting Devices – Airbags Rev. 12/1/14 Low pressure bags This type of bag is constructed of reinforced Neoprene, very similar to medium pressure bags. The top and bottom surfaces are made of multi- layer rubber to provide abrasion resistance. Inside the bag there are reinforcement straps running from the top to the bottom plate. They keep the bag from bulging and prevent some lateral movement. Sizes and capacities are comparable to those of the medium pressure system. Some applications for low pressure air bags include lifting or stabilizing overturned vehicles, especially in situations dealing with thin metal walls such as aircraft. Like medium pressure bags, they provide a large footprint for the area being lifted and minimize the possibility of punch-through. They can also be used to fill voids in trench rescue operations. As with medium pressure bags they provide the rated capacity during the entire lift. As long as maximum surface contact is maintained with the bag, it will lift the rated capacity. Low pressure bags, like medium pressure bags, reach their maximum stability at full inflation. Operating pressure for low pressure bags is around 0.5 bar or 7-8 psi. The same components as medium pressure bags are needed to operate these bags (air source, pressure regulator, controller, relief valves, and hoses). Some manufacturers build their low and medium pressure systems with interchangeable components. MCFRS Driver Certification Program Page 9 of 13 Rescue Squad – Module 4  Pneumatic Lifting Devices – Airbags Rev. 12/1/14 Setup and Operation Establish safe zones When lifting heavy objects there is always the risk of the load shifting or falling. In order to prepare for this event, identify the area that might be affected if the load was to fall or shift and keep personnel and equipment clear from that area as much as operationally possible. When operating around air bags and lifting loads, always pay attention to the load and maintain a stance that will allow for a rapid egress from the danger area should the load shift or fall. Maintain all equipment not being utilized in a centralized area, in the safe zone in order to minimize trip hazards. Whenever possible, work on a flat surface to avoid slippage and shifting of the air bags and or the load. Cribbing Whenever a load is lifted from the ground by any means it must be supported by some type of cribbing material. (See the “Stabilization” module of this manual for more information on cribbing.) When using cribbing in combination with air bags, it is used in two different ways: supporting the load and supporting the air bags. Supporting the load “Lift an inch, crib an inch.” This is a critical part of the overall lifting process. As you lift the load, you must simultaneously crib as you go. This is done in order to prevent the load from traveling unsupported. In the event of a failure somewhere in the lifting system, the load still needs to be supported to prevent dropping the load and causing damage to equipment, the load, and harm to personnel. Supporting the Bags As stated previously, high pressure air bags are rated for their maximum lifting capacity at 1 inch of lift. As the air bag inflates beyond 1 inch, it begins to lose surface contact with the ground and the load. To help alleviate this problem, the air bags must be as close to the load as possible. This can be accomplished by cribbing up to the load prior to inserting the airbag. Additional factors must be considered when constructing a box crib to support a lift rather than simply supporting the load. The top of the box crib needs to be a solid layer of cribbing to maintain full surface contact with the air bag. When working on soft ground, the bottom layer should be solid as well to help distribute the load. When constructing the box crib, a minimum of 3-by-3 crib layout should be used. When a standard 2-by-2 layout is used, the center of the box crib is empty and is therefore not supporting the airbag as it inflates. This can lead to decreased box crib capacity and 3 by 3 Box Crib 2 by 2 Box Crib stability. MCFRS Driver Certification Program Page 10 of 13 Rescue Squad – Module 4  Pneumatic Lifting Devices – Airbags Rev. 12/1/14 Applications Stacking Air Bags High-pressure air bags can be stacked to a maximum of two bags. By stacking bags, we increase our overall lifting height. Recall that the maximum bag height is approximately half the length of its shortest side. When two bags are stacked, their useable heights are added together to provide the total lift height. The larger bag is always placed on the bottom and the smaller bag on the top. The bag with the smaller capacity will dictate the total lifting capacity (e.g. a 19-ton bag stacked on a 26-ton bag would only yield a maximum capacity of 19 tons). Use caution when stacking bags, the more inflated the bags, the more susceptible they are to kicking out. If the load is at an angle, it is recommended that only one airbag be used. Using bags in tandem When two bags are sharing a load at two different points, they are said to be working in tandem. Two bags working in tandem can have their capacities added together in order to determine the total lifting effort, however the bags MUST be lifting the same part of the load. Also, the portion of the load on each bag cannot exceed bag capacity. For example, a 7-ton air bag and 3-ton bag can theoretically be placed in tandem to lift a 10-ton load. However, the 7-ton bag must only see 7 of the 10 tons and the 3-ton bag must only see 3 of the 10 tons. If each bag is responsible for lifting an equal share of the 10 tons (5 tons each), the lift will not be possible. One solution would be to use two 7-ton bags in tandem (each capable of lifting half of the 10-ton load). Recall that air bags are rated at 1 inch of lift. The maximum tandem lifting capacity will be achieved only at that height. This method is useful when presented with a load that exceeds the capacity of the largest bag on hand. MCFRS Driver Certification Program Page 11 of 13 Rescue Squad – Module 4  Pneumatic Lifting Devices – Airbags Rev. 12/1/14 Other Lifting Considerations  Another point to consider when lifting a load, especially if it is resting on a patient, is that when lifting, every action has an equal and opposite reaction. In the event of a patient being pinned under a load, you must crib the opposite side that you are lifting in order to provide a hinge point for the load and prevent sway, which could cause further harm to the individual.  To maintain control of the load and to keep it from shifting, bags should be inflated slowly. This is called “feathering”. Air that is rapidly introduced into the bag will jolt the load and create a chain reaction that may be very difficult to control and could cause the load to shift or fall.  If more than one bag is used for the lift, it may be necessary to inflate one bag at a time to maintain control: lift one bag one inch then the next bag one inch. Inflate each bag at small increments and stagger the inflations. This will allow for maximum surface contact and therefore maximum stability and strength in the bag.  Place the uninflated bags as close to the load as possible to help maximize the lifting height. When the bags are slid under the load they should be just barely touching the load. There should not be a large space between the bag and the load.  Locate a solid surface under the load and use this area as the lifting point, cribbing on both sides of the bags as you lift. Again, the rule is to lift an inch, then crib an inch.  The nipples on the bags can be stacked on top of each other or they can be staggered for easier manageability of the hoses.  In-line relief valves can be placed either at the controller or at the bag. By placing the relief valve at the controller, the person operating the controller has the ability to shut off the air flow to the bag, remove the controller from the system while maintaining bag inflation, and deploy another set of bags in a different location if needed. This is the preferred method because the person operating the shutoff valve will be away from the load. Position the controller in an area with a full view of the lift but in the safe zone if possible.  When lifting the load, one person is responsible for operating the controls on the controller. A second person will be responsible for directing the rescuer at the controller as to which bag to inflate or deflate. The rescuer at the controller will only take commands from this person and those commands should simply be “Up”, “Down”, and “Stop”. Follow each command with the color of the air hose connected to the bag being inflated/deflated (e.g. “Up on red” or “Down on yellow”).  Air hoses are typically stored in a rolled fashion and tend to develop a “memory” in that shape. For that reason, and to prevent kinks and air flow restriction, they should be completely uncoiled and extended before inflation. Using different color hoses for different bags will aid in identification during the lifting operation. MCFRS Driver Certification Program Page 12 of 13 Rescue Squad – Module 4  Pneumatic Lifting Devices – Airbags Rev. 12/1/14 Maintenance  Inspect the bags after every use.  Inflate the bags to half of their working pressure and apply a mixture of soap and water. (It is NOT recommended to inflate an air bag that is not under load to its maximum operating pressure.) Look for leaks or air bubbles.  Check the surface of the bags for cuts, abrasions or any signs of structural damage.  Check that the nipple is firmly attached to the bag and it does not swivel.  Leave the bags inflated for several minutes monitoring for any leaks, this can be seen in the inflation of the bag or on the pressure gauge on the controller.  Inflate and deflate the bags repeatedly in order to exercise the bags and keep them from developing a memory in one position and to provide stretch and movement to the different layers.  Place the bags under an appropriate load and inflate them to their maximum operating pressure, allowing the relief valves to vent and reset. Note the pressure when the relief valve vented and the pressure when it reset. Compare those pressures with the manufacturer’s recommendations.  Air bags should be hydrostatically tested every five years by a qualified service technician. Air bag manufacturers have a stringent battery of tests and standards that must be followed when manufacturing air bags. Some of these tests include bursting tests, abrasion tests, piercing, penetration, and wear resistance, among others. After meeting the requirements of all of these tests some manufacturers may submit their bags to a pressure test of 1.5x their working pressures for a number of minutes. Air bags have a working life of approximately ten years based upon use, storage, and maintenance. MCFRS Driver Certification Program Page 13 of 13 Rescue Squad – Module 4  Hydraulic Tools and Equipment Introduction Hydraulic tools are an important part of a rescue squad’s inventory. They are the backbone of most vehicle extrications and offer an excellent option for heavy lifting operations. As a driver/operator, it is important to understand all aspects of hydraulic tools including not only the tool itself, but their source of power, associated accessories and even the science behind their operation. Theory Fluid Mechanics Hydraulics is the branch of science that deals with the practical applications (as transmission of energy or effects of flow) of liquid in motion. A large part of the theoretical foundation for hydraulics is derived from fluid mechanics, which is the study of the effects of forces and energy on liquids and gases. The term “fluid” is often used interchangeably with the term “liquid”. However, a liquid is actually a type of fluid. Fluids are defined as substances that have a tendency to freely flow or conform to the shape of their container. Both liquids and gases meet this criteria and are considered fluids. Therefore hydraulics is the equivalent of pneumatics when dealing with liquids instead of gases. All fluids are compressible to some extent (changes in pressure and/or temperature will result in changes in their density). However, in most applications the pressure/temperature changes are so small that any changes in density are negligible. Therefore, fluids are often grouped into two categories:  Compressible – a fluid whose density significantly changes with changes in pressure; the volume of a compressible fluid decreases as the pressure exerted on the fluid increases; gases are often considered compressible fluids  Incompressible – a fluid whose density does not significantly change with pressure; the volume of an incompressible fluid will not change as the pressure exerted on the fluid increases; liquids are often considered incompressible fluids Pressure Before proceeding further, it is important to review the definition of pressure. Pressure is force per unit area applied in a direction perpendicular to the surface of an object. Force Pressure Area MCFRS Driver Certification Program 1 of 24 Rescue Squad – Module 5  Hydraulic Tools and Equipment Rev. 1/1/15 Pressure (continued) The SI unit of pressure is the pascal (Pa = N/m2). The U.S. customary system unit of pressure is pounds per square inch (psi = lbs/in2). As the equation on the previous page shows, pressure is affected by changes in the force being applied or the area in which the force is applied. Pascal’s Law One important principle relating to fluid mechanics is Pascal’s Law. The law states that any change in pressure at any point in a confined fluid will result in an equal change in pressure (without loss) throughout the rest of the fluid and to the walls of the container. Example 1: The container on the left contains a fluid. Three P1 = 2 PSI pressure gauges are connected to the container at different depths. As the depth of the fluid P2 = 4 PSI increases, the pressure increases due to the mass above it. P3 = 6 PSI An additional pressure of 4 psi is applied to the fluid. As a result, the pressure will increase P1 = 6 PSI throughout the fluid. According to Pascal’s Law, the pressure increase throughout all parts of the P2 = 8 PSI container will be equal. Therefore, each pressure gauge will increase by 4 psi. P3 = 10 PSI The above example illustrates Pascal’s Law at a basic level. The next example will demonstrate Pascal’s Law in a slightly more complex system. This example will show how forces can be multiplied in hydraulic systems, providing the basis for the design of hydraulic rescue tools. MCFRS Driver Certification Program 2 of 24 Rescue Squad – Module 5  Hydraulic Tools and Equipment Rev. 1/1/15 Example 2: Force = 10 lbs. Load = 100 lbs. Piston 1 Piston 2 Area = 1 in2 Area = 10 in2 Example 2 demonstrates how a hydraulic lift operates at a basic level. A force is applied to the piston on the left. This force causes an increase in pressure on the hydraulic system, which is transmitted to the cylinder on the right. The pressure acts on the piston on the right, which transmits force to lift the block. One very important aspect of the system shown above is that only 10 lbs. on input force is required to lift the 100 lb. block. How can this be? The answer can be drawn from Example 1 and the application of Pascal’s Law: Remember, Pressure (P) = Force (F) / Area (A) So from the diagram, the pressure in the cylinder on the left is: Pressure = Force on Piston 1 / Area of Piston 1 Pressure = 10 lbs / 1 in2 = 10 lbs/in2 = 10 psi Pascal’s Law states that the pressure in the entire system must be equal. Therefore, if there is 10 psi in the cylinder on the left, there will be 10 psi in the cylinder on the right. For the cylinder on the right, the pressure is known. Rearranging the equation yields: Force (F) = Pressure (P) x Area (A) Force on Piston 2 = (Pressure) x (Area of Piston 2) Force on Piston 2 = (10 lbs/in2) x (10 in2) = 100 lbs As this example shows, the input force is increased (multiplied) by a factor of 10 because the area of Piston 2 is 10x that of Piston 1. MCFRS Driver Certification Program 3 of 24 Rescue Squad – Module 5  Hydraulic Tools and Equipment Rev. 1/1/15 Another noteworthy point from Example 2 is the fact that Piston 1 moves farther than Piston 2: Piston 1 Piston 2 Area = 1 in2 Area = 10 in2 Piston 1 Piston 2 moves 10 in moves 1 in The input force was multiplied by a factor of 10 but the resulting movement of the load was reduced by the same factor of 10. It is often said that, “nothing in life is free”. Fluid mechanics is no different. The size and shape of the cylinders does not change. Therefore, since the pressure of the liquid remains the same, the volume must remain constant as well. The volume of liquid in the cylinder can be expressed as: Volume (V) = Area of the Piston (A) x Distance the Piston Moves (D) Therefore, for the cylinder on the left: Volume = (Area of Piston 1) x (Distance Piston 1 Moves) Volume = (1 in2) x (10 in) = 10 in3 If 10 in3 of liquid is displaced in the cylinder on the left, 10 in3 of liquid must move to the cylinder on the right. Since the volume is known, the equation can be rearranged: Distance the Piston Moves (D) = Volume (V) / Area of the Piston (A) For the cylinder on the right: Distance Piston 2 Moves = Volume / Area of Piston 2 Distance Piston 2 Moves = 10 in3 / 10 in2 = 1 in Therefore, the tradeoff to gain increased output force is a decrease in lifting height. MCFRS Driver Certification Program 4 of 24 Rescue Squad – Module 5  Hydraulic Tools and Equipment Rev. 1/1/15 Hydraulic System Components At a basic level, most hydraulic systems are made up of the following components:  Fluid  Reservoir  Pump  Actuator  Valves All of these components can be of different designs and complexities depending on the hydraulic systems application. Fluid Hydraulic fluid (or more accurately, “liquid”) is the medium for carrying the pressure through a hydraulic system that is translated into mechanical force and movement. There is a large variety of options for hydraulic fluid, each with specific characteristics to match specific applications. Some of the basic features of an “ideal” hydraulic fluid include:  Thermal stability  Hydrolytic stability (the ability to resist chemical decomposition in the presence of water)  Low chemical corrosiveness  High anti-wear characteristics  Long life  Low cost To meet these demands, oil-based hydraulic fluids are often utilized. These fluids can be engineered to provide the desired viscosity, anti-wear and anti-corrosion properties with few operating, safety or maintenance problems. However, there are certain applications where oil-based fluids should be avoided. Fire/rescue operations are examples of such situations. Hydraulic fluid exposure to high heat and/or flame could potentially result in a significant fire hazard. For this reason, most fire/rescue-specific hydraulic fluids fall into the category of fire-resistant hydraulic fluids (FRHFs). MCFRS Driver Certification Program 5 of 24 Rescue Squad – Module 5  Hydraulic Tools and Equipment Rev. 1/1/15 The increased demand for fire-resistant hydraulic fluids came about from tragic incidents involving hydraulic fluid fires in industries such as steel mills, foundries and coal mines. Research was aimed at finding suitable replacements for oil-based fluids that could provide comparable hydraulic system performance without a significant increase in cost. Water-Containing Fire-Resistant Fluids: One solution to the problem of fire resistance is water. The introduction of water into hydraulic fluid provides an extinguishing agent should the fluid be exposed to flame. Water glycol and invert emulsions are the two major types of water-containing FRHFs:  Water glycol – a solution of glycol (e.g. ethylene glycol) in water o Contains a variety of additives to provide viscosity, anti-wear and corrosion protection properties as well as a polymeric thickener o Approximately 40% water content o One of the dominant FRHFs on the market o Presents some environmental concerns  Invert emulsion – a stable emulsion of water in oil o Also contains approximately 40% water o The outer phase of oil represents the wetting surface and provides the desired characteristics of oil-based hydraulic fluids o The inner phase of water acts as the fire-retardant o Contains oil-soluble additives to provide corrosion protection and reduce wear as well as emulsion stability Synthetic Fire-Resistant Fluids: The other approach to providing fire resistance was to engineer non-aqueous fluids with chemical properties that either resisted burning or generated products of combustion that would help extinguish any flames. The intent of these fluids was to eliminate the use of water, therefore eliminating the undesirable corrosive and wear characteristics.  Phosphate Esters – the product of a reaction between phosphoric acid and aromatic ring-structure alcohols o Extremely fire resistant o Provide excellent wear resistance  Polyol Esters – synthetic hydrocarbon, the product of a reaction between long-chain fatty acids (derived from animal and vegetable fats) and synthesized organic alcohols o Good fire resistance o Contain additives to provide anti-wear properties, corrosion protection and viscosity modification o Biodegradable MCFRS Driver Certification Program 6 of 24 Rescue Squad – Module 5  Hydraulic Tools and Equipment Rev. 1/1/15 Reservoir The reservoir is simply the storage tank for hydraulic fluid. Reservoirs come in different shapes and sizes depending upon the application. They are designed to provide sufficient fluid capacity for the rated number of operating tools while also maintaining a reserve. In addition, the reservoir must be large enough to hold the hydraulic systems fluid volume when the tools are not in use. In many cases, the reservoir is mounted in close proximity to the hydraulic pump. Pump The hydraulic pump is the device that produces liquid movement or flow. (It is important to note that pumps do NOT generate pressure. In liquids, pressure is a function of resistance to flow. A pump’s job is to generate that flow.) As a review from a “Pumps and Hydraulics” class, pumps are classified as either positive- displacement or non-positive displacement. Most pumps used in hydraulic systems are positive displacement. Positive displacement pumps displace (or move) the same amount of liquid for each cycle of the pumping element. The precise and consistent liquid delivery is possible due to tight tolerances between the pumping element and pump housing. Positive displacement pumps include reciprocating- and rotary-type. Reciprocating pumps are some of the most basic types of positive-displacement pumps. They contain an inlet and outlet and cylinder and piston. Rotary pumps include gear pumps (both external and internal), vane pumps and piston pumps. Spur Gear Pump Axial-Piston Pump Balanced Vane Pump MCFRS Driver Certification Program 7 of 24 Rescue Squad – Module 5  Hydraulic Tools and Equipment Rev. 1/1/15 Power Sources Hydraulic pumps can be powered several different ways:  Manually-operated – for use with single-action reciprocating positive displacement pumps  Electric motor – can be DC or AC operated; common power source for many apparatus-mounted hydraulic pumps  Internal combustion engine – provides portability options; common type is a 4- stroke gasoline small engine  Air pressure – compressed air powers the pump  Power Take-Off (PTO) driven – PTOs can be mounted to the truck transmission and engaged via a switch in the cab; the hydraulic pump is often connected directly to the PTO PTO Pump MCFRS Driver Certification Program 8 of 24 Rescue Squad – Module 5  Hydraulic Tools and Equipment Rev. 1/1/15 Actuator The hydraulic fluid, pump and power source generate flow and pressure. As described in the first section of this module, this pressure needs to be converted back to force and displacement. This is the job of the actuator. Actuators can classified into two types:  Linear (hydraulic cylinders) – convert pressure and flow into linear force and displacement  Rotary (hydraulic motors) – convert pressure and flow into torque and angular displacement Hydraulic motors are used for a variety of things in the fire service. Two common examples are rotation of aerial ladders and hydraulic winches. Hydraulic cylinders control extension and elevation of aerial ladders and many of the hydraulic tools on rescue squads and other rescue apparatus. Types of Hydraulic Cylinders There are two common types of hydraulic cylinders:  Single-Acting – This type of cylinder is unidirectional (operates in one direction). Hydraulic fluid flows into the head of the cylinder through a single port and pushes on the piston, extending the rod. To retract the piston, a valve must be opened to allow fluid to flow back to the reservoir. The piston retraction is made possible either by gravity, the weight of the load or a mechanical force, such as a spring. Examples of single-acting cylinders are floor jacks and bottle jacks. Hydraulic Piston Rod Fluid Port Air Vent MCFRS Driver Certification Program 9 of 24 Rescue Squad – Module 5  Hydraulic Tools and Equipment Rev. 1/1/15  Double-Acting – This type of cylinder is bidirectional (operates in two directions). Unlike single-acting cylinders, there are two ports on a double-acting cylinder, one at each end. To extend the piston, fluid flows from the pump into the port at the cylinder head. As the piston extends, fluid on the opposite side of the piston exits the cylinder through the other port and returns to the reservoir. To retract the piston, a directional valve reverses the fluid flow. Most hydraulic rescue tools utilize double-acting cylinders. Hydraulic Hydraulic Piston Rod Fluid Port Fluid Port One special design of a hydraulic cylinder is the telescoping cylinder. These cylinders contain multiple tubes of progressively smaller diameters nested within each other. Each individual tube represents a stage. Telescoping cylinders have the distinct advantage of increased length at full extension while maintaining a relatively short retracted length. These cylinders can be found in both single- and double-acting designs. MCFRS Driver Certification Program 10 of 24 Rescue Squad – Module 5  Hydraulic Tools and Equipment Rev. 1/1/15 Valves The valves in a hydraulic system control the movement of hydraulic fluid. They are used to control flow between the reservoir and the pump, the pump and the actuator, and flow within the actuator itself. Single-acting cylinders typically have a valve or set of valves to control flow between the reservoir, pump and the hydraulic cylinder. They also contain a valve that allows fluid to return from the cylinder to the reservoir. The diagrams on the right show the basic components of a bottle jack. They contain a single-acting cylinder and a reservoir that actually surrounds the cylinder. The pump is a reciprocating style that is manually operated. Fluid flow between the reservoir and pump and the pump and cylinder is controlled by two ball valves. In the top diagram, the ball valve between the reservoir and pump is open, allowing fluid to flow from the reservoir to the pump. The ball valve between the pump and cylinder remains closed. In the middle diagram, the ball valve between the reservoir and pump closes while the ball valve between the pump and cylinder opens. This allows fluid under pressure to flow into the cylinder, creating lift. The bottom diagram shows the operation of the release valve. This valve is opened to allow fluid to flow from the cylinder directly to the reservoir, enabling the piston to retract. Gravity along with the weight of the load and piston create the fluid movement. MCFRS Driver Certification Program 11 of 24 Rescue Squad – Module 5  Hydraulic Tools and Equipment Rev. 1/1/15 Double-acting cylinders, such as those on most hydraulic rescue tools, have a slightly different set of valves. One of the valves controls the direction of flow within the actuator. Another valve controls the flow between the reservoir, pump and actuator. The diagrams on the right show the basic operation From of the control valve on a the hydraulic rescue tool. Pump There are three different positions: Neutral, Extend and Retract. To the The top diagram shows Reservoir the Neutral position. Fluid flow from the pump is blocked from entering the cylinder. In the middle diagram, the tool operator rotates the control valve to the Extend position. Fluid is able to flow into the cylinder, pushing on the piston and extending the rod. In the bottom diagram, the tool operator rotates the control valve to the Retract position. Fluid flow within the cylinder reverses direction. It now pushes on the opposite side of the piston, retracting the rod. One noteworthy point about the double-acting cylinder shown above is that the surface areas on each side of the piston are not equal. The surface area on the left is decreased by the presence of the piston rod. This decrease in surface area results in a decrease in force applied through the piston rod during retraction. MCFRS Driver Certification Program 12 of 24 Rescue Squad – Module 5  Hydraulic Tools and Equipment Rev. 1/1/15 Most hydraulic rescue tool systems also have a valve that controls the flow of hydraulic fluid to the tool. This valve has two positions. One position pressurizes the port going to the tool. The other position is a neutral, or “dump”, position that bypasses the tool port and recirculates (dumps) the hydraulic fluid back to the reservoir. The diagrams below show the basic operation of the dump valve. RESERVOIR RESERVOIR PUMP PUMP The diagram on the left shows the valve in the neutral position. Pressurized fluid from the pump is immediately returned to the reservoir. The diagram on the right shows the tool being pressurized. Hydraulic fluid flows from the pump, through the valve, to the tool and finally back to the reservoir. MCFRS Driver Certification Program 13 of 24 Rescue Squad – Module 5  Hydraulic Tools and Equipment Rev. 1/1/15 Hydraulic Tools Manually Operated Some of the most basic types of hydraulic tools carried on fire/rescue apparatus are actually not designed specifically for rescue applications. Instead, many manually operated tools are simply “borrowed” from other industries such as automotive repair. Bottle Jacks Bottle jacks are a single acting hydraulic cylinder controlled by a simple reciprocating pump and release valve. The handle on the pump provides the leverage needed to obtain the large output force with a relatively low input force. Bottle jacks can be either single piston or contain telescoping pistons. Many have a threaded post on top of the piston that can be extended for additional height prior to extending the piston. Bottle jacks are designed for axial loading. Any side or eccentric loading could result in jack instability and/or possible hydraulic cylinder damage. Capacities range from 1 ton up to 50 tons. Some bottle jacks are outfitted with a small pneumatic motor that can be used in lieu of the manual pump. These are called “air over hydraulic” bottle jacks. Floor Jacks Floor jacks are another type of single acting cylinder with a manually-operated reciprocating pump and release valve. The hydraulic cylinder is attached to an arm that pivots as it lifts, creating a Class 3 lever. The lifting point on a floor jack is called the saddle. As the hydraulic piston extends, the lifting arm pivots raising the saddle. However, the rotation of the lifting arm also causes the saddle to move horizontally as well as vertically. To compensate for this horizontal movement, floor jacks are mounted on wheels. Capacities typically range from 1.5 tons up to 20 tons. MCFRS Driver Certification Program 14 of 24 Rescue Squad – Module 5  Hydraulic Tools and Equipment Rev. 1/1/15 Portable Hydraulic Kits Commonly referred to as porta-power kits, manually-operated portable hydraulic kits are used in the automotive body repair industry. They consist of a single action reciprocating hand pump and hydraulic hose. The pump can be connected to either a spreading tool or ram. The ram can be outfitted with extensions and various end attachments. These smaller hydraulic tools are useful in tight areas where larger hydraulic rescue tools may not fit. Porta-power kits can range from 4- ton up to 20-ton capacities. Fire/Rescue Portable Hydraulic Kits Many hydraulic rescue tool companies also manufacture manually-operated portable hydraulic kits. Just like those used in auto body repair shops, fire/rescue kits contain a manually-operated single action hydraulic pump and hose with various tools and attachments. One such kit is the Hurst Mini-Lite kit: The Mini-Lite kit contains spreaders, cutters and rams. All of these tools are powered by a hand pump. The cutters provide up to 13,000 and 17,000 lbs. of cutting force. The spreaders are rated for 7,300 lbs. of spreading force. Rams can provide up to 10,000 lbs. of force. MCFRS Driver Certification Program 15 of 24 Rescue Squad – Module 5  Hydraulic Tools and Equipment Rev. 1/1/15 Rabbit Tool The Rabbit Tool is designed for forcible entry applications. It works with the same Hurst Mini hand pump that is used with the Mini-Lite kit and can provide up to 8,000 lbs. of spreading force. The standard Rabbit Tool provides 4 inches of spreading distance. The larger JL-8 Jack Rabbit Tool doubles that spreading distance to 8 inches. Hydra-Ram The Hydra-Ram is another forcible entry tool. Developed by Fire Hooks Unlimited, it is very similar to the Rabbit Tool in operation. However, unlike the Hurst design, the Hydra- Ram eliminates a separate pump and hose. Instead, the hydraulic pump and actuator are integrated into a one-piece tool. Two varieties of the tool exist: the Hydra-Ram with 4 inches of spreading distance and the Hydra-Ram II with 6 inches of spreading distance. Both are rated for up to 10,000 lbs. of spreading force. Paratech HydraFusion Struts Another fire/rescue-specific hydraulic tool is the HydraFusion strut designed by Paratech. These struts are a combination of a standard Paratech strut used for stabilization and a hydraulic ram. HydraFusion struts are powered by a separate manually-operated hydraulic pump. They are rated for 10 U.S. tons of lift with a safety factor of 2:1. Three different sizes of HydraFusion struts provide lifting/spreading distances of 4, 10, and 16 inches. MCFRS Driver Certification Program 16 of 24 Rescue Squad – Module 5  Hydraulic Tools and Equipment Rev. 1/1/15 Hydraulic Rescue Systems Types Hydraulic rescue tool systems are generally identified by their operating pressures. There are two categories: low pressure and high pressure. While there are some similarities, each type of system has unique features and benefits: Low Pressure High Pressure  Operating Pressure: 5,000 psi  Operating Pressure: 10,000+ psi  2-Stage Pumps  2-Stage Pumps  Tools are often heavier than high  Tools are often lighter than low pressure tools pressure tools  Tools tend to operate slower than  Tools tend to operate faster than high pressure, which can provide low pressure, which can provide more precise control and speed but may make precise movement control and movement difficult In both low and high pressure systems, the tools themselves are very similar in function and appearance. The difference is in the pump. Hurst patented the first hydraulic rescue system, the Jaws of Life®, in the 1970’s. It was based on the same principles of fluid mechanics and Pascal’s Law outlined at the beginning of this module. Hurst’s 5,000 psi rescue systems are still widely used today. Advances in technology and a demand for lighter, faster tools led to the introduction of high pressure systems. As the examples using Pascal’s Law demonstrated, the output force of the hydraulic system is dependent upon the fluid pressure and the surface area of the piston. Increasing the operating pressure from 5,000 psi to 10,000+ psi meant that tool pistons could be smaller and still produce the same force as 5,000 psi tools. One of the trade-offs is that high pressure tools must be manufactured with materials and components that will withstand the higher operating pressure. AMKUS is one of the leading manufacturers of high pressure rescue systems. Others include Genesis and Holmatro. Even Hurst manufacturers a line of 10,000 psi rescue tools. MCFRS Driver Certification Program 17 of 24 Rescue Squad – Module 5  Hydraulic Tools and Equipment Rev. 1/1/15 Operation Most hydraulic rescue systems incorporate 2-stage pumps (Holmatro uses a 3-stage axial pump). Hydraulic tools will perform differently based on differences in hydraulic fluid pressure and flow. Higher pressures result in higher output force from the tool. Higher fluid flows result in faster piston movement and tool operation. Unfortunately, both cannot be achieved at the same time. Increases in hydraulic fluid pressure mean a decrease in flow rate. Likewise, increases in fluid flow rate result in decreases in pressure. The key is gaining both benefits from one pump and tool, and hydraulic rescue tool manufacturers have done just that. Hydraulic tool users want maximum speed when operating tools that are not under load (e.g. opening cutter blades). To allow this, the hydraulic pump operates in the low pressure/high flow stage (often called Stage 1). Once the tool meets resistance, the hydraulic pump automatically switches to the high pressure/low flow stage (Stage 2) to provide the maximum operating pressure for the tool. Hydraulic tool operators will sometimes notice this switchover represented by a brief pause in tool operation when it meets resistance followed by movement to finish the spread/cut. Some manufacturers are now incorporating “turbo” or “boost” modes into their pump designs. The idea behind this design is that it allows a user to double the quantity of fluid being supplied to a single tool. The increase in fluid will increase the operating speed of the connected tool during both pump stages. The majority of hydraulic rescue tools utilize a “dead man” control valve. This valve is designed to revert back to the Neutral position once the operator releases his/her grip. This prevents unintended movement of the tool when not in use. They also incorporate check valves to prevent loss of pressure in the tool should fluid flow be interrupted (e.g. a hydraulic line or pump fails). This allows the tool to hold the load until fluid flow can be restored. Control Valves MCFRS Driver Certification Program 18 of 24 Rescue Squad – Module 5  Hydraulic Tools and Equipment Rev. 1/1/15 Spreaders Spreaders use a set of arms connected to a piston rod to apply outward force at the tip of each arm. They can be used for prying and spreading as well as lifting. Spreaders come in different sizes with varying arm lengths. Longer arms provide greater spreading distance at full opening. However, this typically results in a decrease in maximum spreading force. Spreaders utilize a double acting cylinder so force is applied to the arms as they are both opening and closing. This closing force can be used to pull and pinch objects. One thing to note is that the closing force will be less than the opening force. This is due to the fact that the surface area of the piston is not equal on both sides. The double acting cylinder example from earlier in the module shows this difference. There are a variety of different spreader tip designs and accessories. Some tips are designed for gripping surfaces while others are used for peeling. Many tips have holes drilled through them for mounting chains to be used in pulling applications. Whenever spreading, it is important to obtain a good grip with the tips. Spreading should ONLY be done at the tips – using the arms of the tool will result in damage. “Maximum spreading force” is often advertised by manufacturers to promote their