By ED COLLET
Whether the person who drives the engine and operates the pump is called an engineer, operator, or chauffer, he has one of the most important jobs on the fireground.
He must get to the scene while keeping the crew and public safe. At the scene, water must quickly be delivered from the tank to the hoselines prior to a water supply being secured. Various hoselines on the engine will provide options for the water flow to match the size of the fire. The operator will be able to get the correct flow to each line by using the labels and charts with operating pressures determined after testing. All this is done while keeping an eye on the scene, watching gauges, and listening to the engine to help ensure scene safety. That is a lot to do—especially in the early morning hours after being awakened from a sound sleep. Preplanning the engine is a key element in the operator successfully completing all the required tasks on the fireground.
Getting to the fire safely is one of the most important duties of an operator. Doing this effectively involves knowing the physical aspects of the engine (pumper). The engine must be taken to a scale and weighed with a full tank of water, all its equipment, and a full crew complement. This provides the true weight of the vehicle, not just the design estimations of the gross vehicle weight. There are many things knowing the weight does for the operator. Routes may change based on bridge weight restrictions in the response area. Height is another limiting factor in planning response routes. Low underpasses in the response district will require alternate routes. Clearance from overhead wires is a consideration when ladders and towers are positioned but needs to be considered by engine operators as well. Some streets may not be wide enough for some engines during certain times of the week. How will the width of the engine impact response and access to the scenes during these conditions? With ladders being stored in racks over the hosebed, it is critical for the operator to know how much room is needed to drop the ladder rack. The ladders will not be useful if there is a car in the way of the ladder rack or it deploys over a deep ditch. The physical characteristics of the engine impact how the operator approaches driving the vehicle and how it is positioned at the emergency scene. This is the reason knowing the physical characteristics is an important part of the engine preplan.
The operator must know the capacity of the engine’s pump. A plaque is located on the pump panel indicating the results of the pump performance test when the engine was originally certified by the manufacturer. Pump capacity is rated when drafting through 20 feet of suction hose under the conditions outlined in NFPA 1901, Standard for Automotive Fire Apparatus, section 16. For pumps rated at less than 3,000 gallons per minute (gpm) in capacity, full flow capacity must be generated at 150 pounds per square inch gauge (psig) pressure net discharge pressure. Seventy percent capacity must be available at 200 psig net discharge pressure and 50 percent capacity available at 250 psig net pump discharge pressure. When the pump is supplied from a pressurized source, the full capacity of the pump will be available at a discharge pressure of 150 psig plus the inlet pressure. Operators should remember when on a hydrant that it is possible to produce higher than rated flows from the pump at lower pressures, since the full capacity of the pump will not be reached until a net pressure of 150 psig is reached.
The pump operator must fully understand the pump controls. Because of engine technology advancements, mechanical Vernier throttles are not found on newer apparatus. The original electronic throttles used up and down pushbuttons to set engine revolutions per minute (rpm) or discharge pressure. In recent years, electronic Vernier throttle controls have become available as a means to control the throttle and set the governor. This method of control is an appreciated throwback for operators who started out with mechanical throttles. A major difference with many of the new Vernier controls is the direction the knob is rotated to increase rpm. Mechanical Verniers turned counterclockwise to increase rpm while most of the new Verniers rotate clockwise to increase rpm.
Pressure governors allow the operator to run the pump in two modes: rpm and pressure. Pressure mode controls the motor based on the discharge pressure. This takes the place of the discharge relief valve for controlling any pressure surges at the discharges. The attack engine must be controlled in pressure mode to provide protection to the teams staffing the handlines. It is possible for hydrants to supply water at a pressure that keeps the engine at idle and may require throttling the discharge valve. Under these circumstances, the pressure governor offers no protection to the hose team against pressure surges. The operator needs to be vigilant to minimize the impact of pressure surges when operating in this fashion.
When drafting, the governor should be in rpm mode to provide the smoothest control over the drafting operation. The exception to this rule is if the drafting engine is also the attack engine. An attack engine drafting in rpm mode does not provide overpressure protection for the handlines. If a supply engine is not available and the attack engine must draft, the operator should consider drafting in pressure mode to maintain handline pressure protection. For relay operations, using rpm mode eliminates the possibility of the governors on the supply engines getting out of sync, which can result in the supply engines chasing the pressure setpoint. While the attack engine governor is in pressure mode to protect the hose team, the other pumps in the relay run in rpm to maintain a constant water supply.
Without a pressure governor to control the pump pressure, a discharge pressure relief valve must be used. When the discharge pressure exceeds the setpoint, the valve opens and sends water from the discharge to the intake side of the pump. This maintains the discharge pressure at the setpoint, preventing a hose team from taking the punishment of increased pressure because of other lines being closed. It is important that the discharge valve is set no more than 30 psig from the operating pressure based on the NFPA 1901 requirement that a pressure surge of no more than 30 psig occur when valves are closed. The valve must be set for the particular fireground operation. Proper inspection and maintenance of the discharge pressure relief valve are critical to ensure it functions properly.
To get water to the fire quickly, the initial attack is made with water carried in the engine’s tank. The operator must understand the limitation of tank water and how to transition to a secured water source. The most obvious drawback to tank water is the limited amount carried in the tank. Most fire engines carry 500 to 1,000 gallons and tanker-engines can carry 1,250 to 3,000 gallons, or even more. Once the initial fire attack is started, the clock is ticking for the operator to secure a water supply. To give the operator the best indication of the amount of time tank water will last flow, tests must be done on each line to determine how long it can be in service before draining the tank. This information will help the operator determine if help is needed in securing a water supply in the available time.
The tank not only has a limited quantity of water, it has a limited flow rate. NFPA 1901 requires tanks with a capacity of less than 500 gallons to have a tank-to-pump flow of 250 gpm. Tanks with capacities of 500 gallons or more must flow 500 gpm. Testing the flow rate available from the tank to the pump gives the maximum flow rate available at an incident until a water supply is secured. It is very important to know the maximum flow rate to determine if the plumbing will be a limiting factor in fireground operations. Tactics employed while on tank water must be considered when specifying new apparatus and the tank-to-pump flow rates specified accordingly.
Transitioning from tank water to a secure water supply must be practiced so the operator can make the change smoothly and efficiently. For pumps with a pressure governor, the governor should be in pressure mode before the transition takes place so the engine will automatically throttle down when the intake pressure increases. The governor can only take the motor down so far. If the inlet pressure is great enough to produce high discharge pressure, the operator must intervene once the governor has put the motor at idle. At that point, the operator must gate the discharge or let the relay pump operator know to reduce pressure. When a governor is not used to control the pump pressure, the operator must set the discharge pressure relief valve prior to switching from tank water. When the pressure increases from switching to a pressurized source, the valve will control the pressure until the operator can make the needed adjustments. The operator must be familiar with the pump controls that regulate the discharge pressure of the pump to ensure a smooth transition from tank water to a pressurized source.
Securing Water for the Pump
It is possible to have inlets on any of the four sides of the apparatus. It is important to have hose and tools configured in a way that allows the operator to efficiently connect the engine to the hydrant or for a firefighter to connect the hydrant when doing a forward lay. The best way to lay the supply line out on the engine depends on several factors: distance between hydrants, number and location of intakes, amount of supply line carried on the engine, and if hydrants or tankers/static sources are the primary water source.
Each inlet needs a valve to allow it to be used while the pump is operating off tank water. A simple cap on the inlet prevents that inlet from being used if tank water is flowing through the pump. Departments that operate on a municipal water system normally use pressure relieve valves on large-diameter inlets. These valves allow the hydrant to be charged and the air bled from the supply line prior to letting the water into the pump in addition to protecting the pump from high inlet pressures. Bleeding air from the supply line prevents the pump from air locking and is an important step in getting water to the pump. The rush of air ahead of the water in a supply line can fool some electronic governors into reacting like the pump has lost water and bring the throttle down to idle. A solid stream of water should come from the bleed valve before it is closed and the main valve opened. Plumbing the bleeder discharge under the truck with clear tubing lets water flow be seen but not sprayed on the pump panel. This is especially important in colder climates where the spray could ice over the pump panel and create hazardous working conditions. The pressure relief valve is often set and forgotten. It should be tested annually to verify the pressure setting and to flush any sediment that may be in the valve. Operators must be familiar with setting the relief pressure in case the pressure needs to be adjusted on the fireground. For example, when a tandem pumping operation must be performed to supply the fire department connection (FDC) at an extremely tall high-rise building, the engine pumping the FDC will receive water from the engine connected to the hydrant at a relatively high pressure, necessitating an adjustment to its intake relief valve.
A butterfly valve or pressure relief valve that is rated for drafting is needed on one intake if an engine is regularly used for drafting. Intake valves allow the use of tank water while the draft equipment is being set up. Without a valve, it is extremely difficult to send tank water to the fire scene while setting up the drafting operation. By plumbing a line from the priming system to a port on the upstream side of the intake valve, it is possible to prime the suction hose before opening the intake valve. This allows a smooth transition from tank to drafting operation. Air primers provide the simplest means to install such a system on the intake valve. This setup is also useful in extracting the large volume of air present in long lays of LDH since the primer can move greater volumes of air in a shorter amount of time than the smaller bleed valve. With practice, an operator can transition from tank water to drafting with little interruption.
An engine must be configured for the operator to efficiently catch a hydrant within 75 feet. To do this, several short lengths of supply hose are stored on the engine. Short sections (25 feet) of supply hose can be stored in troughs or on the running board under the side intakes. Supply hose can be stored on the front bumper if the engine is equipped with a front intake. The supply hose can be preconnected to the intake and flat loaded to eliminate the step of connecting the supply line to the intake. Preconnecting the supply hose may make it difficult to deploy, depending on the clearance to the intake. The extra room on the front bumper means there are normally minimal issues with interference when deploying a preconnected supply hose on a front intake. Short sections of supply hose can be stored in doughnut rolls in a trough or cabinet near the intake. The doughnut roll provides access to both couplings, allowing the operator to connect one to the intake and walk the other end to the hydrant. At the hydrant, the operator can flush the hydrant, connect the supply hose, and open the hydrant before returning to the apparatus. It is important for the operator to practice catching a hydrant to gain speed and efficiency.
A 50-foot roll of supply hose takes up a lot of compartment space and is difficult to handle. To make a 50- foot section available in an easily manageable fashion, it can be loaded as the first length to come off the hosebed. Making this section a different color than longer lengths in the hosebed will remind the operator that it is a short section. At minimum, it should be marked in a way that is easy to see day or night in any weather.
The hosebed contains a majority of the supply hose. It should be easily accessible, with the tools and adapters to make the connections to the hydrant or another engine within easy reach. If a hydrant valve is used, it is convenient to mount the valve on the tailboard with the supply hose connected. With the increased use of Storz connections, loading the hose for a forward or reverse lay is a moot point. If a reverse lay is used with sexed couplings, the male coupling will be the first out of the hosebed. Putting a double female coupling on the male end will allow for a forward lay without needing to get the coupling out of a compartment. When used as a reverse lay, the female coupling can quickly be removed.
When hydrants are not available, having options for supply lines is important. A hosebed with large-diameter hose (LDH) and a bed of 2½- or three-inch hose provides the operator with the ability to select the size of supply line based on the incident and resources at the scene. The operator can choose 2½- or three-inch over LDH to hand stretch to a water supply apparatus if the distance and required flow rates do not require LDH. A flow of 500 gpm can be achieved for up to 500 feet using three-inch hose with reasonable pump discharge pressures. It is lighter than LDH and requires less water to fill. Five-inch LDH takes 102 gallons to fill a 100-foot section, while the same length of three-inch hose only needs 37 gallons. In limited water supply situations, being able to prevent a significant amount of water from sitting on the ground is beneficial. For long hoselays or large-volume flows, LDH has significant advantages over smaller supply lines. When supply line options are available, operators and officers must have an understanding of the advantages and drawbacks of each hose size.
Fire comes in many sizes—from the small rubbish to the monstrous warehouse with heavy fire loads. It only makes sense that fire engines are equipped with a variety of attack line sizes that allow different water flows. NFPA 1710, Standard for the Organization and Deployment of Fire Suppression Operations, Emergency Medical Operations, and Special Operations to the Public by Career Fire Departments, calls for a flow rate of 300 gpm for a two-story residential building that is 2,000 square feet in size. For structures 13,000 to 196,000 square feet, the requirement is 500 gpm from three handlines flowing a minimum of 150 gpm. These are minimum flow rates, but a firefighter’s intent is to overwhelm the fire. This is done by equipping engines with hoselines that will provide large volumes of water.
There are many ways to set up hose loads on an engine. It is critical that the operator and officer know the capacity and limitation of each line on the engine. Whether a department uses preconnected lines in the middle of the engine, preconnected lines off the back of the engine, dead/static loads off the rear, or a combination of these, it is important to have lines of increasing water flow capacity. The go-to initial attack line of many departments is the 1¾-inch line. A target flow rate for this size hose is 150 gpm, which allows the flow requirements of NFPA 1710 to be met for residential fires by deploying two handlines. With smooth bore and low-pressure combination nozzles, it is possible to achieve water flows approaching 200 gpm with a 1¾-inch line. Two-inch attack lines make achieving flows in excess of 200 gpm more practical. This line is the bread-and-butter hose of many departments, but engines must have larger water flow options to meet the challenge of large home, commercial structures, and heavy fire loads.
Big fire equals big water, which is one reason engines carry 2½-inch hose for attack lines. This hose is useful as an attack line or as a supply for ground monitors or ladder pipes. As a handline, there are various ways the line can be configured: smooth bore with tip sizes from one to 1¼-inch or combination nozzles capable of flowing more than 250 gpm. What is the best way to set up a 2½-inch line? It is a big line used to battle big fire and should be configured to flow the maximum amount of water possible. A 1¼-inch smooth bore can flow 328 gpm and provides the most water from this line. A 2½-inch line with the 1¼-inch tip will match the flow of two 150-gpm 1¾-inch lines. Since the second attack line pulled needs to be an equal or greater size than the first line, a 2½-inch line has the potential to have double the flow of the initial attack line. A 2½-inch line with a one-inch tip flows 210 gpm, which is only a 40 percent increase in flow over a 150-gpm line. Flowing 328 gpm from a 2½-inch line is a 119 percent increase in flow over a 150-gpm handline. A charged 100-foot section of 1¾-inch hose weighs 105 pounds, while the same length of 2½-inch line weighs 213 pounds, a 104 percent increase in weight. If the firefighters are going to work twice as hard to pull a line, it makes sense for the flow to increase by the same proportion. One of the goals of preplanning the engine is to provide an engine that has a variety of options with higher and higher flow rates to allow efficient fireground operation. When it comes to the 2½-inch line, the most efficient tip size to use is the 1¼-inch, since smaller tips increase the work of the crews without an equal increase in fire extinguishing capacity.
Master streams are very effective for providing large flows with minimum staffing. Master stream devices range from the 500-gpm quick-attack monitor to apparatus-mounted monitors (deck guns) flowing more than 1,000 gpm. Whatever the device, it is important for the operator to know the proper pressure settings to get the maximum flow and the best apparatus position to take advantage of the flow.
Deck guns provide a quick means to get a large volume of water on the fire. The only restrictions to using the deck gun to attack are that the fire must be within the reach of the stream and that there must be an opening in the building to allow the water to get to the fire. When the deck gun will be used, the operator must position the apparatus to let the stream hit an opening that will have the most effect.
At one point in history, the deck gun was used when the fire had grown beyond the capacity of the largest handline. Now, with limited staffing, deck guns are looked at as a way to get water to the fire quickly. For a deck gun with stacked smooth bore tips, what should be the smallest tip be? That depends on other high-flow lines the engine carries. A 13⁄8-inch tip provides 502 gpm—the same as the quick-attack monitor carried on many engines. A 1½-inch tip will flow 597 gpm, which is only a slight increase in water flow over the quick-attack monitor. When a quick-attack monitor is available, the best option for the first tip on the deck gun is a 1¾-inch tip, which is capable of flowing 813 gpm. This is a 63 percent increase in flow from the quick-attack monitor. The large tip does sacrifice some distance, but tests can be conducted to determine the amount of distance lost by going to a larger tip. The flow of the combination tip should be checked through the pressure range to find the pressure that gives a flow significantly larger than the largest hoseline or quick-attack monitor available. Departments should test to determine which tip is the best compromise for the flow and distance desired , given the tactics to be used and the other attack lines available.
An engine configured using the concept of substantially increasing flow rates can include the following:
- Two 1¾-inch handlines flowing 185 gpm.
- One 2½-inch handline flowing 328 gpm—77 percent increase in flow.
- One three-inch quick-attack at 500 gpm—53 percent increase in flow.
- One deck gun with 1¾-inch tip as the first tip at 813 gpm—63 percent increase in flow.
The next available line in this configuration flows a minimum of 50 percent more than the next smaller size. When the next size line comes off the engine or the deck gun goes into operation, the incident commander (IC) expects something significant to happen to the fire. Using this philosophy will help ensure the expected results are seen.
The key to getting the anticipated flow from any nozzle and hose configuration is having the proper pump discharge pressure. There are equations for calculating the pressure drop in a given hose size for a particular flow rate. When operating on the fly at the pump panel, there are several rules of thumb the operator can use to determine the correct discharge pressure. There are problems with both equations and rules of thumb. These look at the hose from the nozzle to the discharge without taking into account the plumbing in the pump house. The taps for pressure gauges are normally just down steam of the valve. There can be a significant amount of pressure drop in the pumping between the gauge tap and the discharge, especially for front and rear discharges. The other shortcoming of the equations is they are based on hose properties that may not represent the performance of today’s fire hose.
Testing each discharge to determine the discharge pressure at the pump panel to develop the desired flow is the best way to determine operating pressures. Once testing is done, it is important to develop a detailed pump chart and panel markings to give the pump operator the information in an easy-to-use format. A good pump chart will be color coded to match the hoseline it is referencing. If the nozzle on the hoseline is a fixed-gallonage type, only one pressure value is needed for the line. Variable flow nozzles need a pressure for every flow rate the nozzle can produce. Automatic nozzles need an extensive pump chart to tell the operator the flow over a range of discharge pressures. To simplify operations, dead load flows and pressures should be indicated for every additional length of hose that could be added. It is possible to simply indicate the pressure drop for a single length of hose and have the pump operator multiply by the number of lengths pulled. Adding every length to the chart will reduce error potential at 2 a.m.
Gauges should be labeled with the operating pressure below each gauge. The labels need to be visible in sunlight and in the dark; using reflective numbers is one way to accomplish this. It is helpful to mark the expected pressure with pin striping tape on the gauge face. This allows the operator to know lines are at the correct pressure with a quick glance at the pump panel. Not all hoselines are preconnected. A means to mark the gauges with the correct pressure needs to be near the operator position. A grease marker works well for this. The operator can use it to make notes and other indications on the pump panel.
Preplanning an engine is critical for efficient and smooth fireground operations. When hoseline sizes are well planned, the IC will have the means to deliver progressively larger water flows at any fire. The operator can confidently get tank water to the hose team quickly while securing a hydrant or setting up to be supplied by a water supply apparatus. Then, once a water supply is secured, he can seamlessly transition from tank water. The operator will know the proper pressure to pump each discharge because testing was done to develop a detailed pump chart. The focus of preplanning is training on the engine to understand what is carried on the engine, how it operates, and how all the elements fit together for a successful fire attack.
ED COLLET has been a firefighter II/EMT-I since 2002 and is an Ohio-certified fire instructor. He is a member of the Canal Fulton and Jackson Township (OH) Fire Departments. Two of his focus areas are pump operations and water supply. He has taught pump operations at Bowling Green Fire School since 2015. He has a bachelor’s degree in mechanical engineering from the University of Akron. He is a member of the Ohio Fire Chiefs Water Supply Technical Advisory Committee.