Engine Ops_Pump Op2.pdf

The closer the pumper is to a positive source, the more water it will be able to deliver. The farther the pumper is from the positive source, the less pressure is available due to friction loss. The more pressure is lost, the closer the pump gets back to that initial draft rating. Because of this, i...

The closer the pumper is to a positive source, the more water it will be able to deliver. The farther the pumper is from the positive source, the less pressure is available due to friction loss. The more pressure is lost, the closer the pump gets back to that initial draft rating. Because of this, it is important to make sure the supply pumper is placed as close to the positive source (hydrant) as possible, preferably within Placing the supply engine from the hydrant and having them supply the attack pumper makes the attack pumper feel as if it is operating within of its own positive water source. This allows the attack pumper to have much more water available to it than if it were connected straight to the hydrant. This operation is called pumping in series. Photo from Box 15 Setting up in series as mentioned above also gives the supply pump operator the opportunity to assist the attack pump operator. If the attack pumper begins to run away from water or tries to flow more water than is available to it, the supply pumper can increase its discharge pressure and give the attack operator more pressure. This gives the attack pumper more volume to use on the intake side of the pump (intake pressure). Of course, this relationship of increasing pressure to increasing available volume is not unlimited. Eventually, the supply pump is not able to send any more water through the supply hose, whether that is a 3 or 5 or both. The residual pressure in the water main is not unlimited and will eventually be maxed out. However, if the supply engine is still showing pressure on their intake gauge, that means they still have water to send. This would be an indicator to lay an additional supply line if more water is needed. A second supply line can be used to connect the two engines together. Remember to work toward using a supply line after your initial or vice versa. This increases the ability to flow more water if needed further along in the incident, as long as the positive water source can provide adequate volume and pressure as discussed in this manual. Second Edition 01/31/22 91 Series supply is also used to build a redundancy into the supply system. If the supply pumper is set up near the hydrant and is pumping to the attack engine, this establishes a built-in safety if the attack pump fails. If the attack pumper has a pump issue and is unable to provide pressure or flow to the attack lines, the supply pumper can increase its discharge pressure and pump though the attack pumper. This can provide the needed flow and pressure required to allow attack crews to exit the building or contain the fire. Accomplishing this will take communication from both pump operators. The attack pump operator will have to watch their discharge pressure gauge as the supply pump operator increases the pressure they are sending through the supply lines. The attack pump operator should make sure their attack lines are not over or under pressurized. Keep in mind that any gauges on the pump panel with a digital flow meter built into them will not register anything if the engine loses power. However, the needle pressure gauges on the panel should still show pressure with or without electricity to the truck. This redundancy could make all the difference if something goes wrong. CFD has had an attack pumper failure within the past few years. Luckily, the crews on scene were set up in series per Division SOPs. The supply engine pumped right though the attack engine and provided flow to the attack lines. The fire was extinguished, and all crews left the scene safely. Photo from Box 15 Second Edition 01/31/22 92 Finally, series supply allows pump operators to move the maximum amount of water possible. A few times a year CFD is called to a large fire that requires a great deal of water that will tax our supply system. Moving the most water possible is critical at these incidents. While setting up our supply operations in series is critical to the success of these large incidents, pump operators are always handcuffed by the capability of the water distribution system. Luckily the water mains are large in most industrial areas where these fires occur. When a strong positive source is present, the only issue is deciding how to move the water from the pump in the most efficient manner. The preferred way to move extreme volumes of water is to use three hose lines into a trigate appliance. Be sure to keep the trigate close to the supply engine (two short sections of and one section of works best). Next, lay a 5 supply line from the trigate to the attack pumper. Using the hose to send the water from the trigate over longer distances allows for less friction loss within the hose. Several CFD instructors have tried a variety of ways to move big water, and this setup was by far the best when tested. Understand that this setup is not something that will be used on most fires. However, when the most water possible is needed, this method is something to consider. This article was designed to emphasize the benefits of establishing series supply during CFD pump operations. It is important to emphasize that this article by no means encompasses all water supply operations. For those who wish to understand more, the amount of material out there is almost never ending. Get out there and challenge yourself to be better and become the best pump operator possible. If you have questions, ask and use the resources around you to continue to learn and better yourself. Photo from Box 15 Second Edition 01/31/22 93 OVERVIEW When functioning in a series supply operation, there are some basic guidelines for both the attack and supply pump operators to follow. These guidelines will help pump operators navigate the complicated pumping scenarios that can occur at large incidents This section will discuss driver priorities on the fireground and the basic rules for attack and supply pump operators when they are functioning in a series supply DRIVER PRIORITIES It is crucial to remember that the driver priorities never change, regardless if it is the attack driver or the supply driver Priority One Get water for the crew For the attack engine, the crew is the attack hose line or the primary hose line deployed For the supply engine, the crew is the attack engine Priority Two Get water for yourself Once you have water for the crew, get water for yourself For the attack engine, water can come from either a simple supply connected directly to a close hydrant, or from a supply line laid from the supply engine. Remember that a series supply is always preferred. If a simple supply is established from the attack engine to a hydrant, a supply engine should still be added into the system to create a redundancy and maximize the water source For the supply engine, the water will come from a hydrant Priority Three Get water for everyone else Once the water supply is established, get water for everyone else. This can include filling Second Edition 01/31/22 94 ATTACK ENGINE GUIDELINES Work toward establishing a series supply Once the attack tank is depleted to ¼ of a water. This causes the attack engine to use ¾ of their tank water first, then the ater. This gives the supply driver the time to secure a permanent water supply Once the attack driver opens their supply intake, they should close their tank-topump to isolate their remaining ¼ tank for emergency use The attack driver should not charge the backup line on tank water alone. This ensures that the limited tank water is going to the interior crews o The attack driver should at least wait until they have the supply before charging the backup line The attack driver should not fill their tank o Until a permanent water source is secured, all available water should be going to the crews operating on the fireground o This also gives the supply driver more time to secure a hydrant before running out of water Your engine means you make the connections! Never rely on someone else to make the proper connections to your engine Second Edition 01/31/22 95 SUPPLY ENGINE GUIDELINES Supply drivers should spot the hydrant like they plan to use it o Position the engine one car width away from the curb on the side you plan to connect the hydrant to. Position the engine so the hydrant is nearly in line with the rear wheel, or nearly in line with the front cab door Even if the attack engine is on their own hydrant, it is still preferred to build a redundancy into the system by creating a series supply with the attack truck o Pump Principles section of this manual When pulling hose off any truck, never chuck hose into a pile on the ground o The hose is nice and neat on the truck. There is no reason to make a tangled mess of hose on the ground. Pull the hose off the truck in a straight line until you reach the objective The supply driver should make the attack engine feel as if they are on a good hydrant Charging the supply line to around 80-100 PSI is usually a good starting point The supply driver should continually evaluate their discharge pressure by staying in contact with the attack driver to determine if more or less pressure is needed Sending the attack engine 80-100 PSI may initially be at a static pressure (no flow). The supply driver should be aware of this and anticipate a potential drop in pressure once the attack truck begins to use the supply o Pump Boss engines will throttle up the RPM to maintain the set pressure (only if the operator sets the pressure initially and is in Pressure Mode), but older CFD manual throttle engines will require the driver to manually increase the RPM to maintain the desired discharge pressure Once a hydrant supply is established to the supply engine, recheck the discharge pressure to ensure that it is not too much for the attack operator o Pump Boss engines will throttle down on their own, but occasionally a hydrant in the city will provide 100 PSI or more. With the pump at idle, the discharge pressure could easily be around 140 PSI o If the desired discharge pressure is only around 100PSI, the supply operator will need to take action to decrease the discharge pressure to the attack truck. (Refer to the Pump Principles section for ways to decrease the discharge pressure) Once on hydrant water, the supply engine driver should radio to command that they are on a hydrant o This will allow everyone to know that pending any issues, there is an unlimited supply of water. Pump operators can now move on to their third driver priority as discussed in the Driver Priorities section When speaking on the radio, identify yourself as Engine __ Driver o Engine ___ is the identifier for interior crews. The proper radio identifier should be used when attempting to talk to another engine driver o Correct Engine 2 Driver to Engine 15 Driver o Incorrect Engine 2 to Engine 15 Second Edition 01/31/22 96 By Todd Shultheis The Columbus Fire Department has recently made the decision to begin purchasing all new engines with two-stage fire pumps. This decision has brought up two major questions. What are the differences between a single-stage pump and a two-stage pump, and which mode should the two-stage pump be operated in? Before we attempt to answer these questions, it would be helpful to discuss a brief history of fire pumps and how they have evolved. Decades ago, most fire departments used two-stage fire pumps in their pumpers. Two-stages were required to meet the pressure demands of the industry. Two things happened that resulted in a shift to single-stage pumps. The first was the shift to diesel powered engines in the fire service. These engines were capable of delivering much greater horsepower than that of a gasoline engine. With more horsepower being transferred to the fire pump, the pump became more powerful. The second change that happened in the pump industry was the invention of the dual-sided pump impeller. The impeller is the object inside the pump that is connected to the drive shaft and spins. The spinning action draws water into the pump and creates pressure. Prior to the invention of the two-sided impeller, a single-sided impeller was utilized. A single-sided impeller is only capable of pulling water into the pump from one direction. The two-sided impeller allows the pump to draw in water from two directions, which results in more efficient operations. Essentially, the improved dual impeller was now able to draw twice as much water into the pump housing, creating greater pressure. As a result, when you couple a powerful diesel engine to a more efficient pump design, the need for the two-stage pump dwindled. Modern single-stage pumps are capable of meeting the NFPA 1901 standard for automotive fire apparatus and are capable of meeting the demands of most fire departments across the county. If modern single-stage pumps are capable of meeting the needs of most firefighter situations, why use a two-stage pump? The City of Columbus, just like many other metropolitan cities, has many high-rise buildings. The pressure requirements necessary to pump water through a standpipe system to the upper floors of these buildings is significant. The higher-pressure capabilities of a two-stage allows for the required pressures to be obtained with less work by the engine and pump. The efficiency of the two stages allows the pump to run at a lower RPM. A decreased pump RPM also allows the engine in the pumper to run at a lower RPM. This decrease in demand results in less wear on the engine and also lower fuel consumption. Another factor to consider is heat buildup. Anytime a pump is engaged it is creating heat from the spinning of the impeller. If the impeller is allowed to spin at a slower speed, then less heat is generated. This results in less wear on the pump housing and its components as the water in the pump will remain cooler. The examples above are several of the advantages of the two-stage pump. Second Edition 01/31/22 97 The basic operation of a two-stage pump is very similar to that of a single-stage pump. The pump goes into gear in the same manner and the throttle and valves work the same. The major difference is the fact that a two-stage pump has two different modes in which it can operate. The two modes are pressure and volume. A decision must be made by the pump operator as to which mode the pump will be operated in during an incident. This is a tactical decision that should be discussed in advance with the company officer in order to avoid complications during firefighting operations. A two-stage pump in volume mode works essentially like a single-stage pump. The full volume capabilities of the pump are available as well as the pressure limitations. Water enters both pump impeller intakes simultaneously, reaches the desired pressure, and exits on the discharge side of the pump. Sometimes volumeof the water moving through both impeller intakes at the same time, side by side. A two-stage pump in pressure mode works quite differently. In pressure mode water only enters through one side of the impeller when coming from the intake. The water is brought up to pressure and transferred into the second impeller, where the pressure is once again increased. Finally, the water exits into the discharge side of the pump. Pressure mode essentially pressurizes the water twice with each impeller only required to do half the work. This mode is also referred -mode. FIGURE 1: These two images show schematics of a twostage pump working in both pressure and volume modes Second Edition 01/31/22 98 Figure 2 The diagrams below are simplified diagrams showing the flow of water in each mode and the respective effects on the GPM and PSI The following diagram numbers are designed to create an easy to understand conceptual foundation Actual discharge capacity of a two-stage pump in pressure mode is approximately 70% of the total capacity of the pump (70% of 1500 = 1050) The flow and pressure numbers in Figure 2 are based on a 1500 GMP pump. As can be seen in volume mode, 750 GPM enters both impellers simultaneously and is brought up to the rated 150 PSI. As the water leaves each impeller, it is combined resulting in the 1500 GPM but still at 150 PSI. In pressure mode, 1050 GPM enters the first impeller where it is brought up to 150 PSI. That 1050 GPM is then transferred into the second impeller, where an additional 150 PSI is added for a total of 300 PSI. In pressure mode the pump doubles the pressure, but cuts the volume of water by 30%. There is no question that a two-stage pump is capable of reaching greater pressures. It has also been shown that in pressure mode the pump runs at a lower RPM to obtain the needed pressure, resulting in less wear and lower pump temperatures. The question that then arises is in which mode should the pump be run for routine firefighting? Many argue that since less wear and tear is created in pressure mode, it is the preferred mode. Before that decision is made, the limitations of pressure mode must be addressed. When a two-stage pump is run in pressure mode, the volume capability of the pump is 70% of the rated capacity. Therefore a 1500 GPM pump in pressure mode is only capable of flowing approximately 1050 GPM. There are many situations during firefighting operations when 1000 GPM of Second Edition 01/31/22 VOLUME MODE 1500 GPM at 150 PSI DISCHARGE 750 GPM at 150 PSI 2nd stage 750 GPM at 150 PSI 1st stage INTAKE PRESSURE MODE 1050 GPM at 300 PSI DISCHARGE + 150 PSI 2nd Stage 1050 GPM at 150 PSI 1st Stage INTAKE 99 water is not enough. Below are some examples of when the demand for water would exceed the capability of a two-stage pump in pressure mode: Multiple line operations Quick attack operations Deck gun operations Ladder pipe operations In any of the instances listed above, it is possible that more than 1000 GPM would be required from the fire pump. If the pump operator had started the initial attack with the pump in pressure mode, then a mode transfer would be needed. In order to switch the mode from pressure to volume, the throttle of the pump must be dialed down. Forgoing this step could result in a dramatic spike or drop in the pressure on the subsequent lines coming off the pump. What happens if there is a crew on an attack line inside the structure when the transfer needs to take place? Taking pressure away from them is not an option. The only way to safely accomplish the transfer would be to pull the crew out and suffer the consequences of interrupting the fire attack. This could have devastating effects on the outcome of the operation. As to the argument that the pump should be run in pressure mode due to decreased wear on the vehicle, this may be -the-road trucks and are capable of running for hundreds of thousands of miles before needing maintenance. No fire truck ever comes close to that workload. Modern fire pumps are also designed for thousands of hours of operations. The reality of the fire service is that the average pumper might have its pump engaged for a couple of hours per month. Wear and tear certainly happens, but not to the extent that we should be basing our tactics on its prevention. Starting a two-stage pump in volume mode for fires not involving a high rise eliminates the need for having to transfer modes in the middle of active firefighting operations. The full volume s other advantage of running in volume mode as stated earlier is that the pump operates just like that of a single-stage, which most firefighters are familiar with. The training and discipline needed to operate the pump are decreased. The pump operator has enough things to deal with and think about. Eliminating the questions of when the mode needs to be changed or if it needs to be changed allows him or her to focus on the task at hand. Figure 3 shows a breakdown of when pressure mode and volume mode can be utilized. Single Attack Line Fires Multiple Line Operations Ladder Pipe Operations Quick Attack/Deck Gun Standpipe Operations Overhaul Second Edition 01/31/22 Volume Mode Yes Yes Yes Yes No Yes Pressure Mode Yes Varies No No Yes Yes 100 The disadvantage of using a two-stage pump in pressure mode during normal firefighting operations has been demonstrated. Does this mean that pressure mode should never be utilized other than when working at a high-rise fire? As mentioned earlier, a two-stage pump in pressure mode does allow the pumper to work at a lower RPM and a cooler temperature. It would be beneficial for a pump operator to make the switch to pressure mode once the fire has been extinguished and once overhaul operations have begun. Commonly, a single charged line is left in the structure during overhaul and while waiting for an arson investigator. Many times, this can result in the pumper being left in pump gear for an extended period. This is an instance where slowing the pump down, decreasing the workload of the truck, and lowering the temperatures would be advisable. Pressure mode would accomplish that mission. In conclusion, there is no question that a two-stage pump should be operated in pressure mode during high rise operations or any time elevation is a factor. Pressure mode is also advisable after a fire has been contained and overhaul is being performed. In all other instances, volume mode should be utilized. Volume mode gives the pump operator the full GPM output of the pump and eliminates the need to interrupt fire ground operations to switch modes. As with everything in the fire service, there are no absolutes. Engine companies should discuss pump operations and train on them. Fire officers should size-up a scene and make adjustments as necessary. A two-stage pump is a tool that gives firefighters more options on the fire ground and can be very useful when used properly. Be Safe! 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