DOP Ch. 10 Notes
Learning Objectives
Explain making the pump operational. (NFPA 1002, 2014: 5.1.1, 10.2.2 & NFPA 1002, 2017: 5.1.2, 10.2.2)
Summarize facts about operating from the water tank. (NFPA 1002, 2014: 5.1.1, 10.2.2 & NFPA 1002, 2017: 5.1.2, 10.2.2)
Explain considerations when operating from a pressurized supply source. (NFPA 1002, 2014: 5.1.1, 10.2.2 & NFPA 1002, 2017: 5.1.2, 10.2.2)
Summarize facts about operating from a static water supply source .. (NFPA 1002, 2014: 5.2.1, 5.2.2 & NFPA 1002, 2017: 5.2.3, 5.2.4, 5.2.5)
Describe actions taken for sprinkler and standpipe support. (NFPA 1002, 2014: 5.2.4 & NFPA 1002, 2017: 5.2.7)
Explain actions taken when troubleshooting pumping operation. (NFPA 1002, 2014: 5.1.1 & NFPA 1002, 2017: 5.1.2)
Engage and disengage a power take-off (PTO). (NFPA 1002, 2014: 5.2.1, 5.2.2, 5.2.4, Skill Sheet 10-1 & NFPA 1002, 2017:5.2.4, 5.2.5, 5.2.7, Skill Sheet 10-1)
Engage and disengage a pump. (NFPA 1002, 2014: 5.2.1, 5.2.2, 5.2.4, Skill Sheet 10-2 & NFPA 1002, 2017: 5.2.4, 5.2.5, 5.2.7, Skill Sheet 10-2)
Perform pump operations from the apparatus water tank. (NFPA 1002, 2014: 5.2.1, Skill Sheet 10-3 & NFPA 1002, 2017: 5.2.4, Skill Sheet 10-3)
Make the transition from the apparatus water tank to an external pressurized water supply. (NFPA 1002, 2014: 5.2.1, Skill Sheet 10-4 & NFPA 1002, 2011: 5.2.4, Skill Sheet 10-4)
Operate from a pressurized water source. (NFPA 1002, 2014: 5.2.1, Skill Sheet 10-5 & NFPA 1002, 2011: 5.2.4, Skill Sheet 10-5)
Draft from a static water supply. (NFPA 1002, 2014: 5.2.1, 5.2.2, 5.2.4, Skill Sheet 10-6 & NFPA 1002, 2017: 5.2.3, 5.2.4, 5.2.5, 5.2.7, Skill Sheet 10-6)
Supply water to a sprinkler/standpipe system. (NFPA 1002, 2014: 5.2.4, Skill Sheet 10-7 & NFPA 1002, 2011: 5.2.7, Skill Sheet 10-7)
Case History
An instructor was reviewing pumping operations with another firefighter using a 2½ inch (65 mm) line supplied by a hydrant into the pump with a 1¾ inch (45 mm) line stretched to discharge water.
The training included switching from tank water to a pressurized source, which was completed a number of times.
During one evolution, as the tank fill valve was being opened, a loud noise and water spraying from inside the pump panel was observed.
The instructor and firefighter withdrew slightly and then moved to shut down the operation.
The top portion of the pump panel was forced loose by water pressure and flew open, damaging the panel and nearby components.
The line from the tank fill valve to the tank had come off, allowing water from the 2½-inch (65 mm) pipe to spray directly at the pump panel.
Driver/operators must wear full PPE even when operating at the pump panel to lessen the chance of injury.
Reacting quickly to shut down or modify operations when a problem is detected may help reduce the impact of mechanical problems.
Introduction
After gaining an understanding of the operating theory behind fire pumps, the driver/operator must become proficient operating the fire pump.
This chapter contains information regarding the operation of a pump under a range of circumstances.
The driver/operator must first make the pump operational and then prepare to use at least one of three sources of water to supply the pumping operation:
Onboard water tank
Pressurized water source
Static water source
Pump operations at buildings equipped with automatic sprinkler and standpipe systems are also featured.
The instructional information provided is generic in nature in an effort to include the basic operating practices for many makes and models of fire pumps.
Consult the operator's manual for your assigned apparatus and model pump.
Making the Pump Operational
Making a fire pump operational, commonly referred to as "putting the pump into gear" begins after the apparatus is properly positioned and the parking brake has been set.
Proper positioning for pumping apparatus was detailed in Chapter 4, Positioning Apparatus.
Some apparatus have a feature that prevents the pump from throttling up or shifting into pumping gear if the parking brake has not been set.
The operation of parking brakes was discussed in Chapter 3, Apparatus Safety and Operating Emergency Vehicles.
Most apparatus are designed so that the procedure for making the pump operational is performed entirely from the cab of the vehicle.
IFSTA recommends that the wheels be chocked every time the driver/operator exits the cab.
The placement of chocks provides an added measure of safety in the event the apparatus jumps into road gear or overrides the parking brake system.
Operating from the Water Tank
Water supply from the onboard water tank is the sole source of supply for many incidents.
In other cases, the driver/operator begins to operate with the water in the tank and then transitions to an external supply source.
The driver/operator must be able to make the transition quickly and efficiently with no disruption to the incident operation.
Putting the Pump into Operation
When the fire pump has been made operational, the driver/operator is ready to operate the pump to generate sufficient pressure to create an effective fire stream.
The initial water source is often the apparatus water tank.
Upon exiting the cab and chocking the apparatus' wheels, the driver/operator then proceeds to the pump panel.
While the specific steps may vary slightly from apparatus to apparatus, the common steps for performing pump operations from the apparatus water tank are described in Skill Sheet 10-3.
Another method for putting the pump into operation involves opening the appropriate discharges before you increase the discharge pressure by increasing engine speed:
Open the tank-to-pump valve first.
Open the discharges to the hoselines to be used.
Open the valves, and the hoselines begin to fill with water.
Increase the throttle and the pressure in the hoselines will increase.
While the pump is in operation, the driver/operator must perform the following:
Monitor all gauges associated with the engine as well as the operation of the fire pump.
Adjust the throttle until the desired flow rate is achieved if a flowmeter is in use.
During the fire attack, hoselines may operate intermittently.
The pump may overheat if water is not flowing for an extended period of time, and the discharge pressure is maintained at a high level.
In order to prevent this possibility, a means of moving water through the pump must be implemented.
If the pump is equipped with a circulator, bypass, or booster cooling valve, it can be opened and set to circulate water back into the tank.
This action provides some amount of cooling without wasting any water.
The tank fill line may also be used to circulate water through the onboard tank in order to maintain cooling.
The driver/operator must be aware that the tank fill line may be plumbed with a pipe large enough to cause pump cavitation when operating using the onboard tank.
Sufficient cooling may be achieved by partially opening the valve.
If the apparatus is so equipped, other measures include discharging water into the atmosphere or feeding a booster line back into the tank to circulate water.
Monitor the water level in the onboard tank.
Estimate the amount of time that water in the onboard tank will last based on the rate of consumption.
Ensure that personnel who are operating in dangerous areas are aware when the water level drops and are withdrawn before running out of water.
Make a fairly accurate judgment of the duration of time a water supply will last based on the size of the tank and the approximate flow rate for specific hoselines, nozzles, and appliances.
If the pump is equipped with a flowmeter, a reading of the amount of water flowed through the line may be available.
Transition to an External Water Supply
When operating at an incident requiring more water than is carried aboard the apparatus, it is necessary to transition to an external water supply before depleting the onboard tank.
To begin the transition to external water, the driver/operator should:
Connect the supply line into an appropriate intake of the fire pump.
Make the connection to an intake with a closed gate valve. The pump is already in operation. Air in the empty supply hose will enter the pump and may cause problems for the attack lines already being supplied.
Open the bleeder valve on the gated intake so that air can escape ahead of the water supply. When the air has been purged from the bleeder and a steady stream of water drains from the valve, it may be shut. The water supply is now at the pump and ready for the transition.
Continue to adjust the discharge pressure by using the throttle until the intake gate valve is completely open.
When this is complete, the pressure-regulating devices may need to be adjusted again.
Operating from a Pressurized Supply Source
The two basic pressurized water supply sources that a driver/operator will encounter are a fire hydrant or supply hose from another pumper.
With either of these sources, water enters the pump under pressure.
As the discharge volume from the fire pump increases, the incoming pressure from the supply source may drop due to friction loss in the water system.
If the discharge flow volume is increased too much, the intake pressure from the supply source may be reduced to a point that may damage the pump or water supply system.
Pumping at a low residual pressure (below 20 psi [140 kPa]) while being supplied by other apparatus is equally dangerous.
This may cause the supply hose to collapse, interrupting the supply of water.
It may also lead to cavitation of the pump.
Driver/operators should maintain a residual pressure of at least 20 psi (140 kPa) on their master intake gauge at all times during pumping operations.
Water supply systems must maintain a residual pressure of at least 20 psi (140 kPa) within their mains for several reasons; contamination from sources outside the main may occur if the pressure in the main drops too low.
In addition, overtaxing the water system may cause sediment and debris that has formed in older pipes to loosen, which could in turn damage the piping or reduce the water flow.
Fire departments should maintain a working relationship with local water supply officials in order to ensure proper use and peak effectiveness of their system.
Operating from a Hydrant
Hydrant operations are basically the same whether a pumper supplies attack lines directly or supplies another pumper from the hydrant in a relay operation.
In either case, safe practices must be followed for the activities that take place.
Choosing a Hydrant
Several factors affect the choice of a hydrant.
Safety and firefighting needs may indicate that the closest hydrant to the fire may not be the most prudent choice.
Depending on the constraints of the water supply system, the closest hydrant may be unable to supply the required volume of water and would require laying additional lines to another hydrant of greater capacity.
Additionally, the hydrant may be too close to the fire creating a safety hazard for personnel and apparatus.
Many water supply districts use a color-coded marking system to indicate the capacity of hydrants in their system.
In order to make an informed hydrant selection, a thorough knowledge of the water supply system is necessary.
Hydrants served by large mains that are interconnected in a grid pattern receive their supply from several directions and usually have lesser amounts of sedimentation and deterioration.
Typically the least desirable hydrants are those located on "dead end mains" that are served by smaller mains from only one direction.
Once a hydrant has been selected, the pumper must be hooked to it without delay.
The hydrant may be opened briefly and flushed of any accumulated debris before connecting the intake hose.
Making a Forward Lay
One of the most common ways for a pumper to be supplied with water from a hydrant is by making a forward hose lay.
A forward lay consists of stopping at the hydrant, dropping the end of one or more supply hoselines at the hydrant, and then proceeding to the fire location.
A potential problem for the forward lay depends on the distance from the hydrant to the fire.
In a long lay with large flow demands, a pumper may need to be placed at the hydrant to make use of all available pressure.
Another consideration is the amount of supply hose carried on the pumper.
If the water supply pumper runs out of hose before it reaches the fire scene, it will be necessary to either bring in more hose and continue the forward lay or have the next arriving pumper lay from the first pumper to the fire and set up a relay pumping operation.
Some jurisdictions connect the line to the hydrant and work off hydrant pressure, while others await the arrival of a second pumper to hook up to the hydrant and supply the lines.
Some departments use a four-way hydrant valve to aid the process of making a forward lay.
This valve allows the original supply line that was laid by the first pumper to be immediately charged using hydrant pressure.
The valve has a second discharge, usually 4½ or 5 inches (115 or 125 mm) in diameter, equipped with a shutoff valve.
The steps for the operation of a four-way valve:
Connect the valve to the hydrant.
Connect the original supply line, laid by the first pumper, to the supply line outlet.
Open the hydrant. The clapper valve has operated to allow water to flow in the supply line.
Connect the second pumper to the large diameter pumper intake connection on the four-way valve.
Open the pumper intake valve. Open the four-way valve on the hydrant to supply the pump without interfering with the flow through the original supply line.
Connect one of the pumper discharge outlets to the second intake of the hydrant valve.
Making a Reverse Lay
With the reverse lay, hose is laid from the fire to the water source.
This method is used when a driver/operator first reports to the incident location to size up the scene before laying a supply line.
Water supply must be established in cases where the apparatus that lays the hose must remain at the water source, as in drafting operations, or when an increase in hydrant pressure is needed.
Executing a reverse lay is a common method for setting up a water supply operation using medium diameter hose as a supply line.
With medium diameter hose, it is necessary to position a pumper at the hydrant to supplement the pressure to the supply hose.
A common two-pumper operation provides for an attack pumper and a water supply pumper.
Getting Water into the Pump
After connections to the hydrant are made, conduct several checks before opening the hydrant.
Close the tank-to-pump valve if the intake is not equipped with a shutoff valve.
If the intake is equipped with a shutoff valve, it is acceptable to charge the intake line and bleed off the air while still pumping in water from the tank.
When the pump is full of water and the pressure in the system has stabilized with no water flowing, a reading of the pressure on the master intake gauge indicates the static pressure in the water supply system.
The driver/operator should record the static pressure reading before he or she begins to pump.
Putting the Pump in Service
Running a pump without water for a significant amount of time may cause the components to overheat and wear out faster, but the driver/operator may engage the pump before leaving the cab if it appears that water will be introduced within a few minutes.
When operating a two-stage pump, the driver/operator must set the transfer valve to the proper position before increasing the throttle to build the required discharge pressure.
Open all valves slowly, especially when using large diameter hose.
Additional Water Available from a Hydrant
When a pumper is connected to a hydrant and is not discharging water, the pressure shown on the intake gauge is static pressure.
When the pumper is discharging water, the intake gauge displays the residual pressure.
The difference between the two pressures is used to determine how much more water the hydrant can supply.
Several methods are available for making this determination:
Percentage Method
First-Digit Method
Squaring-the-Lines Method
Percentage Method
To use the percentage method, first calculate the drop In pressure as a percentage. This may be accomplished by using the following formula:
First-Digit Method
The first-digit method is a quick and easy way to calculate available water using psi and gpm. However, this method cannot be used with metrics.
Step 1: Find the difference in psi between static and residual pressures.
Step 2: Multiply the first digit of the static pressure by 1, 2, or 3 to determine how many additional lines of equal flow may be added.
Squaring-the-Lines Method
When using the squaring-the-lines method, the driver/operator must note the static pressure of the water system before any pump discharges are open or know the usual static pressure in the water supply system under normal circumstances.
You must also have a close idea of the volume of water initially flowed by the pumper.
After establishing these figures, determine the additional amount of water available and square the number of lines currently flowing and multiply this by the original pressure drop.
Formulae:
Shutting Down the Hydrant Operation
All changes in flow should be made slowly and smoothly to avoid water hammer and pressure surges on water systems.
When shutting down the water supply operation:
Bring the engine rpms to idle gradually.
Discontinue a pressure control device if in operation.
Close valves in a slow and smooth motion.
Close the hydrant; operate the valve in the same slow and smooth manner to avoid the possibility of water hammer and potential damage to the water supply system.
Operating from a Static Water Supply Source
All fire department pumpers should be capable of pumping water from a static water supply source.
In most cases, this source is located some distance below the level of the fire pump.
It is not possible to pull water into the pump. However, it is possible to evacuate some of the air inside the pump creating a pressure differential (partial vacuum), which allows atmospheric pressure acting on the surface of the water to force the water into the fire pump.
In order to create this condition, an airtight, noncollapsible waterway (hard intake hose) must be used between the fire pump and the static water source.
Drafting Operations
In order to create this condition, an airtight, noncollapsible waterway (hard intake hose) must be used between the fire pump and the static water source.
As the water begins to move through the pump, additional pressure losses are encountered.
Any hose or appliance creates a certain amount of friction loss.
The amount of friction loss is proportional to the velocity of water moving through it.
The amount of friction loss in the intake hose depends on the diameter and length of the hose as well as the intake strainer and any adapters in use.
Atmospheric Pressure During Drafting Operations
The ability to overcome losses in pressure is limited to atmospheric pressure at sea level (14.7 psi [100 kPa) or 30 inches Hg).
This pressure decreases approximately 0.5 psi (3.5 kPa) or 1 inch of Hg for each 1,000 feet (300 m) of altitude gain.
Cavitation During Drafting Operations
In theory, cavitation can be described as water being discharged faster than it is coming into the pump.
This condition occurs when air cavities are created in the pump or bubbles pass through the pump.
During cavitation, the pressure drops below atmospheric and the boiling point of water drops to the point that the water changes to a vapor and creates a void composed of water vapor, or steam
There are a number of indicators that a pump is cavitating.
The pressure gauge on the pump will fluctuate and hose streams may pulsate creating a distinctive popping or sputtering sound as the water leaves the nozzle.
Selecting the Drafting Site
The most important factor in choosing the draft site is the amount of water available.
If the location features a static body of water such as a pool or lake, the size of the body becomes significant.
In order for a pumper to approach its rated capacity using a traditional strainer, there must be at least 24 inches (600 mm) of water over the strainer.
When using a portable tank or swimming pool for drafting operations, a low-level strainer is the appliance of choice.
Type and Quality of Water
Although almost any type of water may be used for fire suppression, pumping nonpotable (untreated) water may be harmful to the pump.
Dirty or sandy water may potentially cause serious problems.
As dirty water passes through the pump, it is forced Into the packing by discharge pressure.
Accessibility
Accessibility to a water source is an important factor in selecting a drafting site.
All fire pumps meeting NFPA®and Underwriter's Laboratories Inc. requirements are rated to pump their capacity at 10 feet (3 m) of lift.
Connecting to the Pump and Preliminary Actions
Place the apparatus directly at the location from which the intake hose may be deployed.
Set the parking brake and chock the wheels when the final position has been achieved.
Inspect the gaskets to be sure that they are in place and no dirt or gravel has accumulated inside the coupling.
Priming the Pump and Beginning Operation
When the pump has been made operational, priming the pump will begin the drafting operation.
The entire priming action typically requires 10 to 15 seconds from start to finish.
When up to 20 feet (6 m) of intake hose lifting a maximum of 10 vertical feet (3 m), it may take as long as 30 seconds (45 seconds in pumps larger than 1250 gpm [5 000 L/min]) to accomplish this.
The most common cause of an air leak is an open drain or valve.
Other sources for potential leaks are the gaskets on the couplings of the intake hoses.
Successfully priming the pump, the throttle setting should slowly be increased before attempting to open any discharges.
Constant movement of water through the pump is required in order to prevent overheating.
Operating the Pump from Draft
Operating from draft is demanding for the apparatus and driver/operator alike.
This operation requires diligent monitoring of the gauges associated with the pump as well as the engine.
The most common source of problems while operating at draft. If the discharge pressure gauge begins to fluctuate with a corresponding loss of vacuum on the intake gauge, air is most likely coming into the pump along with the water.
Defective pump packing may also cause air leakage. If there is an excessive amount of water leaking from the packing, in a steady stream instead of dripping, the packing may be the cause.
Shutting Down the Operation
When preparing to shut down a drafting operation, slowly decrease the engine speed to idle, take the pump out of gear, and allow the pump to drain.
After the pump has been drained and the connections removed, operate the positive displacement primer for several seconds until primer oil or fluid comes out of the discharge from the priming pump.
The fire pump should then be thoroughly flushed when a supply of fresh water is available, unless the pumping operation was conducted using a very clean static water supply.
Sprinkler and Standpipe Support
Fixed fire suppression systems are an integral part of the fire protection features of many buildings.
The driver/operator is responsible for providing adequate support to these systems during fireground operations.
These suppression systems commonly consist of the automatic sprinkler and standpipe systems. The steps for supplying water to both automatic sprinkler and standpipe systems are listed in Skill Sheet 10-7.
Supporting Automatic Sprinkler Systems
During sprinkler activation for a fire, the fire department must be prepared to augment the water supply to the sprinkler system based on local policy.
This may include compensating for obstructed or inadequate water supply or improperly closed valves.
The location of the fire department connection (FDC) as well as the closest hydrant or static water supply should also be identified.
Specific requirements for pump pressure at each building should be noted per local policy.
The fire department connection may consist of a Siamese with at least two 2½-inch (65 mm) female connections connected to a clappered inlet, or one large diameter connection.
Supporting Standpipe Systems
Fire attack teams may connect to the 2½ inch (65 mm) or 1½ inch (38 mm) connections located at strategic points on each floor.
Standpipe systems may be wet or dry, depending on the fire code requirements for a particular occupancy.
Some wet pipe systems contain water under pressure and may be used as soon as a hoseline is stretched and the valve is opened.
Shutting Down the Hydrant Operation
All changes in flow should be made slowly and smoothly to avoid water hammer and pressure surges on water systems.
When shutting down the water supply operation:
Bring the engine rpms to idle gradually.
Discontinue a pressure control device if in operation.
Close valves in a slow and smooth motion.
Close the hydrant; operate the valve in the same slow and smooth manner to avoid the possibility of water hammer and potential damage to the water supply system.