Pump Operations Overview PDF

SECTION TOPICS Pump Principles FRC Pump Boss 400 Pressure Governor Estimating Available Hydrant Flow Discharge Relief Valve Understanding Supply: Advantages of a Series Supply Intake Relief Valves Driver Priorities and Supply Guidelines Back Flushing the Pump Single-Stage vs. Two-Stage Pumps...

SECTION TOPICS Pump Principles FRC Pump Boss 400 Pressure Governor Estimating Available Hydrant Flow Discharge Relief Valve Understanding Supply: Advantages of a Series Supply Intake Relief Valves Driver Priorities and Supply Guidelines Back Flushing the Pump Single-Stage vs. Two-Stage Pumps: The Debate Continues Cold Weather Maintenance SECTION OBJECTIVES Understand basic Pump Principles concepts Understand how to use Pressure Mode and RPM Mode on the Pump Boss Understand how to calculate the estimated available hydrant flow Explain the Pump Boss Operator/RPM limit, Low Water, and No Water modes Understand the advantages of using a series water supply State how a discharge relief valve and a Pump Boss are different Understand the three main priorities for drivers/pump operators Understand how to set and maintain a discharge relief valve Understand general guidelines for attack and supply pump operators Understand the purpose of intake relief valves and how to check them Describe the difference between a single-stage vs. a two-stage pump State how to back flush a pump and where to get replacement screens Understand volume mode and pressure mode and when to use them Understand maintenance guidelines for pumps during cold weather Second Edition 01/31/22 80 INTRODUCTION Water in, water out, maintain pressure, and secure a supply these are some of the fundamentals stressed in a five-day crash course in the Training Academy to prepare recruits to operate a CFD engine. Becoming proficient and developing a full understanding of hydraulics can take years of training, research, and experience to achieve. However, the first step to becoming a professional pump operator is to obtain a fundamental understanding of the principles taught at the recruit level. This section will discuss information pertinent to basic pump principles. WHY IS THE GATING DOWN OF INTERIOR HANDLINES LESS DESIRABLE THAN GATING DOWN EXTERIOR LINES? During engine operations, situations may arise where several hose lines will be placed into service line requiring 130 PSI have 50 PSI extra at the nozzle (if it is pumped at the same 130 PSI pump discharge pressure as ). 50 PSI extra (100 PSI at the nozzle) would increase the nozzle reaction from 98 lbs to roughly 196 lbs. This would likely be more hazardous than a handline that is under pumped. The pump operator will need to gate down the valve for set it to the proper pressure. This would need to be done while the handline is actively flowing to achieve an accurate pressure. In this case, the pump operator has gated down the discharge valve to set the lower pressure handline to its proper operating pressure. However, the pump operator must understand several things when gating down interior handlines. When a discharge valve is gated down, it in turn creates a smaller discharge opening. This smaller opening would normally not create an issue for interior crews if all things remain the same within the system (the amount of water coming in vs. the amount of water going out). However, things generally do not stay the same, given the dynamic nature of the fireground. A sudden change in the residual supply (such as the tank fill lever pulled fully open, master streams being deployed from the attack engine, or other large lines being opened within the same hydrant system) will leave the interior attack line/crew more susceptible to a sudden loss in nozzle pressure due to a sudden reduction of the residual pressure. The more a line has been gated down, the greater the risk to the interior attack crew. If the line is gated down and a loss of pressure is not recognized/remedied promptly by the pump operator, the interior crews could be left with an ineffective stream and without protection. Also, if a line had been gated down early in the incident, the operator may forget they had done so. It is not as obvious when our handwheel valves are not fully open, compared to the pull levers on the tank-to-pump and tank fill valves. Generally, the goal of exterior or defensive streams is to provide an effective stream that reaches the intended target. If the pump operator encounters a situation where they need to charge another stream but there is too little residual pressure left in their supply, they may opt to gate Second Edition 01/31/22 81 down some of the already flowing exterior/exposure lines. These exterior streams can be gated down to allow water to be diverted to the other streams. Gating down these lines will lead to a loss in stream reach and GPM; however, this may be acceptable based on the situation, especially if it allows another fire stream to be opened that can protect another exposure. Reducing flow on exterior lines is generally not a safety concern since exterior crews are not inside the IDLH environment. The pump operator will need to ensure that these gated lines still maintain their effectiveness. In addition, gating down interior lines generally would be considered after other avenues of reducing pressure have already been tried (reducing engine RPM to reach the highest discharge pressure if it was set too high initially). To be clear: gating down interior lines to set them to their proper pressure is an acceptable practice (after other methods of attempting to lower the pressure have failed). However, gating down interior lines below their normal operating pressures to provide additional water elsewhere should be avoided. WHY SHOULD THE SUPPLY ENGINE BE AS CLOSE AS POSSIBLE TO THE HYDRANT? WHY SHOULD OUR ENGINES BE IN SERIES? Initially, series supply came about due to an era of unreliable pumps and vehicles. Placing engines in series created a built-in system backup in case of mechanical failures. Placing an engine as close as possible to the hydrant can help firefighters get the most benefit from the water supply operation. Ideally, the supply engine would be placed directly on the hydrant (using a short . Doing so provides the least amount of friction loss possible from the positive source (hydrant). This becomes more significant for longer lays with greater supply demands, leading to a loss in hydrant pressure. The supply engine being on the hydrant allows the supply pump engine, essentially bringing the hydrant to the attack engine. From there, the supply engine pump operator can continue to increase supply pressure to the attack engine as the volume demands increase until they have maxed the given hydrant s supply capabilities (residual pressure reaches 10 psi or less as shown ). Having the attack and supply engines operating in series not only maximizes the supply; it also creates a redundancy/fail safe in the system. If the attack engine malfunctions, the two pump operators must then coordinate to use the supply engine to pump through the attack engine and continue the fire attack. WHEN . ENGINE? fill the hose, allowing more of the supply engine s water to reach the attack engine instead of , and a single line over a shorter lay can provide up to 800 GPM, more than enough to supply a primary and a backup can provide large amounts of flow over longer distance for use on longer hose lays and initial defensive operations, supply operators must recognize that Second Edition 01/31/22 82 of hose initial supply line and a hydrant supply is not established quickly, a majority of the supply engine s gives the option of maximizing the tank water between the two trucks (minimizing tank water in the hose) while giving the supply operator time to hook into a hydrant. To satisfy Division SOPs, point in the incident. WHY DO I HAVE TO BE CAREFUL WHEN FLOWING MASTER STREAMS USING TANK WATER WITH A PUMP BOSS? While the Pump Boss has proven itself as an extremely useful tool, it can still have drawbacks in certain situations. One scenario where extra care should be taken is when the decision is made for the initial attack line to be a master stream sized line (deck gun, MQA, LDH discharge) while still on tank water. If a discharge is opened rapidly, the amount of water being discharged may be enough that line from the tank to the pump cannot keep up with the sudden demand. This commonly occurs when the operator opens the deck gun discharge rapidly while the pump is already set at its operating pressure (in an attempt to provide immediate stream reach and flow). This may cause the Pump Boss to believe it is now running away from water; it . . ne RPM to bring the pressure up prior to opening the discharge may cause a further decrease in pressure, . cause the loss of valuable water and time on scene. UNDERSTANDING THE IMPORTANCE OF RESIDUAL SUPPLY One of the most important things a pump operator can pay attention to is their residual pressure on the intake gauge. More often than not, a pump operator will not know their true initial static pressure due to at least one line already being in operation prior to establishing a supply (a high initial static pressure does not necessarily mean there will be sufficient volume). For this reason, the rules for calculating the amount of available hydrant water will generally apply to this type of scenario (Refer to the Estimating Available Hydrant Flow section of this manual for more information on how to perform these calculations). Understanding these percentages becomes critically important during operations when the Incident Commander inevitably requests more lines be placed into operation. Knowing how much water is remaining from the hydrant allows the pump operator to give potential options to the Incident Commander instead of just denying their request. For example, the pump operator could say, I will have to shut down one of the exterior lines first. make the decision to either change tactics or designate companies to increase the water supply capabilities for the scene. Sometimes, taking a few extra seconds on a large-scale defensive fire to understand the true initial static pressure without flowing any water and obtain an overall layout of the fire scene will allow pump operators to be proactive in their supply operations. Second Edition 01/31/22 83 WHAT DO I DO WHEN I HAVE TOO MUCH DISCHARGE PRESSURE? Generally, excessive discharge pressure is the result of too much intake pressure from a supply engine or hydrant; there are several options to deal with this issue. The Pump Boss engines will attempt to deal with this by throttling down until the set discharge pressure is achieved. What if the engine is at idle and the pressure is still too high? The first solution could be to radio to the supply driver, see if they have their discharge pressure set too high, and ask them to throttle down to an appropriate pressure. If they are also at idle and there is still too much pressure, the supply driver could consider placing their engine into neutral (the supply driver would have to be diligent and ready to resume pumping if supply demands change). There is also the option of dumping excess pressure via another discharge on the engine, such as the tank fill or a discharge away from the pump panel. This is a viable option if the weather permits and it does not cause additional issues on scene. What about subzero temperatures? If creating an ice hazard is a concern, the pump operator could alternate between using their tank water and the supply line by closing their intake and operating off tank water. Once they need to fill their tank, they would open their intake again. This process would be repeated for the duration of the incident. This method requires the attack operator to be extremely focused on their tank supply and the opening and closing of valves to ensure there is an uninterrupted flow of water. If the above options have been attempted already and there is still too much pressure, the attack operator could gate down their intake valves. If the pressure is still too much, the attack lines could be gated down to keep hose lines at the appropriate pressure as long as volume is still sufficient. Second Edition 01/31/22 84 OVERVIEW Estimating the available flow from the water supply source is something that is not often used on the fireground by the pump operator. Many fires will be contained with a single well-placed line and the tank water from the first due attack and supply engines. Larger incidents that escalate beyond the capability of the initial tank water may begin taxing the available water supply to the point that the engine pump operators will need to estimate the available hydrant supply. The general rules of thumb listed below are meant to assist the engine operator on scene. Having an understanding of the remaining supply can allow the operator to make informed decisions on the fireground regarding what lines can and cannot be placed into operation. Having this knowledge can allow the operator to inform the incident commander of the need for a separate water source and whether or not more lines can be added. If the operator can inform the incident commander that the current hydrant system is close to its max capacity, the incident commander can begin to direct companies to establish a supply from a different water main to be brought to the scene. STATIC AND RESIDUAL PRESSURE To start estimating the remaining supply, the pump operator will need to be aware of the initial pressure that they are receiving from the hydrant. As soon as water is brought into the pump from one of the intakes, the Master Intake Gauge should begin showing pressure. This initial pressure is considered the Static Pressure Pressure on the intake gauge with no water flowing. Once a discharge is opened and water begins flowing from the intake side of the pump out through the discharge side of the pump, there will be a decrease in pressure on the Master Intake hydrant. Residual Pressure Pressure from the hydrant with water flowing. Second Edition 01/31/22 85 This initial change from Static Pressure to Residual Pressure is what will be used to determine the amount of water remaining in the hydrant system. It is recommended that engine operators note their initial Static Pressure whenever possible to provide an accurate estimate of available water if the incident escalates and requires more water. When considering the percentage drops below regarding potential hydrant flow, it is understood that a hydrant supply is generally established after the initial attack line/s are flowing. Defensive scenarios or ladder pipe operations will generally involve securing the hydrant prior to flowing water. In cases where the first line is off the truck and flowing prior to a water supply being established, the operator should not factor this line into their remaining supply. This is often reading on the intake gauge when their supply is cut in as their Static Pressure despite the first line/s already being off and flowing. PERCENTAGE DROPS Using the initial drop from Static Pressure to Residual Pressure, the operator can now estimate the remaining flow in the system by changing the PSI drop to a percentage. This can be done by dividing the PSI drop by the initial intake pressure. For instance, if the PSI drop was 10 PSI and the initial intake pressure was 100 PSI, then 10/100=0.1. Now convert 0.1 to a percentage by multiplying by 100 (just move the decimal point two places to the right). By doing so, the operator determines there was a 10% drop from the initial intake pressure. An important part of using the percentage drops below is for the operator to know the GPM of the discharge that caused the drop. Without knowing the GPM that caused the percentage drop, the operator cannot make an accurate determination of the remaining supply. CALCULATING AVAILABLE HYDRANT WATER Percentage Drop 0-10% Drop from Static Pressure 11-15% Drop from Static Pressure 16-20% Drop from Static Pressure >20% Drop from Static Pressure Remaining Supply 3x the amount that caused the drop 2x the amount that caused the drop 1x the amount that caused the drop ½ the amount that caused the drop (or less) Examples 100 PSI Static Pressure will be used to simplify the explanation regarding percentage drops for these examples. In these examples, the water supply will be a simple supply setup (attack engine directly on the hydrant); the engine on the hydrant will have the most accurate information regarding t especially for extended lays, but these operations will require greater communication between when an attack engine arrives on scene early enough and has a hydrant close enough for them to establish a simple supply prior to the arrival of the second engine. Second Edition 01/31/22 86 0-10% Drop Looking at the gauges on the right, the initial Static Pressure once the hydrant is brought into the pump is around 100 PSI. line flowing, the Residual Pressure is now reading 90 PSI. This is a 10 PSI drop in intake pressure. The pump operator does the math (10/100=0.1) and determines this was a 10% drop from the Static Pressure. A 0-10% drop means the remaining supply is three times the amount that caused the drop. Since 250 GPM was the amount that caused the drop, there is roughly 750 GPM remaining from the supply (250 x 3 = 750). 11-15% Drop The starting Static Pressure is again 100 PSI. The same 250/50 backup line is then flowing, the Residual Pressure in this example has dropped to around 85 PSI. This is a 15 PSI drop in intake pressure. The pump operator does the math (15/100=0.15) and determines this was a 15% drop from the Static Pressure. An 11-15% drop means the remaining supply is two times the amount that caused the drop. Since 250 GPM was the amount that caused the drop, the hydrant has roughly 500 GPM remaining in the system (250 x 2 = 500). 16-20% Drop The starting Static Pressure is again 100 PSI. A deck gun is then opened, flowing 500 GPM with a 1deck gun flowing, the Residual Pressure is now reading around 80 PSI. This is a 20 PSI drop in intake pressure. The pump operator does the math (20/100=0.2) and determines this was a 20% drop from the Static Pressure. A 16-20% drop means the remaining supply is one times the amount that caused the drop. Since 500 GPM was the amount that caused the drop, the hydrant has roughly 500 GPM remaining in the system (500 x 1 = 500). Second Edition 01/31/22 87 >20% Drop For drops greater than 20%, it becomes much harder to determine the amount of water that is remaining in the hydrant supply. If the drop is more than 20%, there is roughly half of the amount of water that caused the drop remaining in the system. For drops greater than 20%, crews should carefully monitor their intake pressure when opening more discharges. Failure to do so could allow a sharp drop in Residual Pressure to lead to a loss of pressure on the interior handlines. A high Static Pressure means nothing regarding potential GPM. Until a known amount of water engine connects to the same water main and begins operations, it will affect the available water supply. Close monitoring of residual intake pressure is critical for the safety of crews operating in an IDLH atmosphere. For this reason, pump operators should always attempt to maintain at least a 10 PSI residual pressure. The formula for calculating remaining supply based on the percentage drop was obtained from the book Fire Service Hydraulics and Pump Operations by Paul Spurgeon. Second Edition 01/31/22 88 Establishing a constant, uninterrupted water supply to interior attack crews is the number one goal of any pump operation. A good water supply is viewed by many pump operators as a safety net, and it is the number one priority after the attack lines are charged. However, how that water supply is established can be a frequent topic of discussion. Throughout the years, CFD has found that setting up a series water supply offers many advantages over a simple water supply. This article is designed to help illustrate the benefits of series water supply. However, before moving into the benefits of series water supply, it is important to understand what simple supply and series supply are and how they relate to the ratings and capabilities of CFD fire pumps. So, what is a simple supply? A simple water supply is established by placing a hose on the main intake valve of the pump and connecting it straight to the hydrant. This will work for many fires as a supply; however, it does present some limitations. By connecting the hydrant directly to the fire truck, the pump operator is at the mercy of the hydrant in regards to its flow and its ability to provide adequate pressure to the attack pumper. Also, if a mechanical failure occurs in the pump, there is no failsafe in the system; crews inside will be forced to operate on hydrant pressure as they evacuate the structure. Second Edition 01/31/22 89 A series supply is established by connecting a supply hose (either or between the intake of the attack pumper and the discharge on a supply pumper. The supply pumper will then use a supply hose to connect to a hydrant. Using this type of supply setup has many advantages, and it is preferred when pumping fires. Before discussing all the benefits of series supply, it is crucial to understand some basic information about CFD fire pumps. It is first important to understand how these pumps are rated. CFD pumpers all utilize pumps rated at 1500 gallons per minute (GPM). What this means is that each pump is tested and rated to discharge 1500 GPM while at a draft. What does at draft mean? When pumps are tested, the water supply is established from a static source. This means that the water being used is being vacuumed out from a static water source like a pond or lake. This article will not go into great detail on how drafting works, but there is a lot of great information out there for those who want to read more on that topic. Once a draft is established, the water is pulled from the pond into the intake side of the pump; it is then pumped out the discharge side of the pump at 150 PSI. The amount of water leaving the pump is measured in GPM. This is how a pump rating at 150 PSI is achieved and measured. While 1500 GPM is a great deal of water, our pumps are actually capable of moving much more. To do so, a positive water supply is required. In most places in the city, there are hydrants every These hydrants provide a positive source of water, meaning they supply water with pressure from the water mains. Hydrants are a much better supply source than a static source like a pond or lake. By using a positive source, pump operators can flow more than the 1500 GPM that the pump is rated for. However, instead of simply connecting a pumper to a hydrant, there are additional factors pump operators should consider to maximize their water supply. Second Edition 01/31/22 90