Developing Pump Discharge Pressures

Developing Pump

Discharge Pressures

Henderson Training Center 03-20-10 014

 

 

Pump operators have one of the most critical jobs within the fire company. They must be able to deliver the troops in a timely and safe manner and provide them with an adequate water flow to suppress the fire as fast as possible. This involves securing a water supply sufficient enough to produce the required fire streams to get the job done, and to develop the required streams by means of a combination of hose evolutions and proper pump operations.

 

A pump operator should understand the operation and capabilities of all appliances that have anything to do with the movement of water, such as:

1 – Type of nozzles (smooth bore, automatic, selectable gallonage, fixed gallonage, etc.)

       2 – The flow range of the nozzles

3 – Flow range, requirements, and capabilities of master stream appliances

       4 – Hose capabilities, supply and discharge

 

There are things that a pump operator needs to know in regards to physics when it comes to delivering water on the fire ground.  Here is a list of things to know about moving water that will help the pump operator to have a better understanding of what is required of him.

*The understanding of friction loss in both hose and plumbing.

*GPM

*Elevation gain or loss (head pressure)

*Properly reading gauges

*Nozzle exit or base pressure

*Nozzle friction loss

 

Besides all of the above-mentioned items, the pump operator needs to develop the proper discharge pressure to provide the energy to move the water through the hose evolution and discharge it onto the fire.

 

There are several things in a hose evolution that require pressure to move the proper amount of water. Back in the olden days when buckets were used, the only energy required to move the water was in the form of human power in bucket brigades. In today’s water delivery system, pressurized water is used to overcome things such as friction loss in fire hose, plumbing, and appliances, head pressure loss from elevation and an exit pressure from the stream producing fire nozzle (also known as nozzle pressure).

 

There have been several methods used over the years to calculate the required discharge pressure, some worked well and others not so well. There is a standing joke in the fire service that says “throttle up until the firefighter and nozzle come off the ground, then back her off a couple of pounds”. I wonder how many people practice that these days. How about this one, “pump 150”, whether it is for a handline of any size (diameter and length), for master streams, relays, or for building fire protection systems? If water comes out the other end, the correct discharge pressure is being developed. I think you know these methods leave a lot to be desired.

 

Probably one of the most common methods used for calculating the right discharge pressure is the use of fireground hydraulics. This is a mathematical formula that is based on the size and length of the hose line, the amount of water being delivered (GPM), appliance friction loss, elevation gain or loss, building plumbing loss, and nozzle pressure. The old formula 2Q squared plus Q was designed for 2-1/2” hose calculations and it is my understanding that the numbers were based on 2-1/2” pipe, not fire hose. In other words dimensions. A coefficient could then be used in the formula to apply it to other hose diameters. I know this formula works on paper with the help of a calculator, but is it practical and accurate? No and no.

Kent, WA June 2002-15

 

Looks like spaghetti, how do you figure this one out?

 

First off, hose has different characteristics than pipe. It curves and sometimes kinks and it’s even been known to expand when it’s charged in some cases. Pipe doesn’t do that. It is a proven fact that the same size hose at a given flow can have different friction loss characteristics from different manufacturers. The following statistics show just that.

 

To mix it up even more, you know as well as I do, that there are occasions that the length, diameter, flow, and other key components of a hose evolution may not be known, now what? The formula can’t be used if you can’t supply all of the numbers. For those that can work the formula at the fire, my hat goes off to you, it’s pretty tough.

 

In recent years IFSTA has streamlined the formula to make it more accurate but in my opinion it’s not the best method to use. If there is a good characteristic about the fireground hydraulics it is that they usually calculate a higher than reality pressure.

 

Flow meters have seen their way into the apparatus industry utilizing an electronic readout of the amount of water flowing. Although these instruments can be accurate, most require calibration to remain in good operating service. From what I have seen, most departments do not calibrate their flow meters. If a flow meter is to be used I recommend the type that also has a pressure gauge. This makes for a reliable backup.

 

Pump Charts

 

A pump chart is a reference chart for all discharge evolutions that assists the pump operator in developing pump discharge pressures for any hose evolution a department may encounter. Pump charts should be designed to be as easy as possible to read. Make sure the letters and numbers are as large as possible and keep it in a place that is easy to access and has a light for night time use. A pre-determined pressure should be calculated for all pre-connected evolutions, such as pre-connected handlines, fixed master stream appliances, and any evolution that will always be the same. The numbers calculated from the flow test should reflect the discharge gauges that are being used by the apparatus. Most discharge pressure gauges read in 10 psi increments. Pressures should be rounded off to the nearest increment on the gauge to make it more practical to read. I would recommend rounding off to the next highest increment.

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Pre-connected lines remain the same thus allowing for a pre-determined discharge pressure.

 

 

 

Let’s take a look at a method that allows for developing pump discharge pressures that work every time. This is mainly for pre-connected lines or lines that are the same length and flow every time as well as fixed master streams and quints. The method involves conducting flow tests through the use of flow meters and pitot gauges. These tests are not done at the fire, they are used to develop pump charts that should be placed on the fire apparatus and used as a reference guide by the pump operator. The flow meter should be calibrated before the test begins to guarantee accuracy. This is done by first using a smooth bore nozzle to measure a flow with a certified pitot gauge, which measures the nozzle pressure. The flow meter can then be calibrated to the flow that is measured through the smooth bore. I like placing the flow meter on the supply line at the intake of the pump. This allows the discharge evolution to be exactly like it would be in a real operation without the insertion of the flow meter tube. Most manufacturers of flowmeters require a certain amount of straight water travel through the hose or plumbing about 10 feet before and after the flow meter tube for best results.

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Flow meters should be used whenever possible for determining accurate discharge pressures.

 

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Handheld pitot gauge is used to measure the exit pressure of a water delivery appliance.

 

Besides having predetermined pump discharge pressures, there is also a need to have a friction loss chart for the various sizes of hose that are used. The reason for this is simple. There are times that lines have to be made up at the fire which could involve various lengths of hose. By having a friction loss chart the pump operator can add up the amount of hose that is being used on a specific line cross-referenced to the friction loss chart to come up with the required pump discharge pressure.

3

Storage hose beds can also be used to develop operations, which can result in an undetermined amount of hose.

 

You still need to set up a discharge line and determine the required flow you are testing through the methods just explained to you in the last paragraph. There also needs to be two in line pressure gauges connected into the discharge line 100 feet apart to measure the friction loss. These gauges also need to have 10 feet of straight hose entering into them for best results. The friction loss is determined by subtracting the lower pressure from the higher pressure on the two gauges.

 

Finally, it’s important to flow test all pumping apparatus in the fleet because their designs in regards to plumbing design and gauge placement could be different from one another thus having different pump discharge pressures. Every unit should have its own pump chart developed from itself

 

 

 

 Handlines.

him

 

The handline evolution is the most basic discharge evolution used by firefighters in regards to its simplicity. There are two basic parts, the hose and the nozzle. The most common form of this evolution is the pre-connected handline.

 

Preconnects

 

The method used for calculating the correct pump discharge pressure for the pre-connected handline is the basic flow tests previously mentioned. For combination nozzles a flow meter is used and for smoothbore nozzles either a flow meter or handheld pitot gauge can be used. It’s important to flow the lines from the actual pre-connected discharge because they are usually smaller in diameter than the 2 ½ discharges and can have numerous bends in the plumbing design that could affect the required pressure. Additionally the discharge gauge may be located further away from the end of the discharge plumbing than a standard 2-1/2” discharge gauge. Here is an example of what would be on the pump chart

 

1-3/4” 150 GPM Handline X 200’ With A TFT Automatic 100 psi Nozzle

150 psi PDP

2-1/2” 325 GPM Handline X 200’ with a 1-1/4” Smooth bore 50 psi Nozzle

100 psi PDP

 

Handline Assembled At The Fire.

If the handline is developed or assembled at the fire scene and has a different length than the pre-connected lines the final calculation is done by using the friction loss section of the chart. First the length of the handline needs to be determined. Next the friction loss chart needs to be referenced to the correct size of hose and GPM. The Friction loss numbers are listed for 100 foot sections so simply divide the length of the hose by 100 and multiply the answer by the actual friction loss listed on the chart to come up with the friction loss for the entire line. It should be noted that the friction loss can be calculated for 50 foot sections if so desired. Finally add the nozzle pressure based on the actual nozzle that is to be used.

 

It’s important to understand that a handline like this as compared to the same length line on a preconnect can vary a little. Remember you are working with two different types of discharges and the pump discharge pressure for the assembled line is developed from numbers on the chart versus using a flow meter for the pre-connect line. Here is an example of what would be on the pump chart.


 

Friction loss for 100‘ sections of hose

 

1-3/4” @ 150 GPM     25 psi

2-1/2” @ 250 GPM     15 psi

2-1/2” @ 300 GPM     20 psi

2-1/2” @ 328 GPM     25 psi

5”      @ 1000 GPM    5 psi

 

   GPM   100’     200’    300’      400’         500’

2-1/2”  328    25 psi   50 psi   75 psi   100 psi     125 psi

Plus 50 psi for the nozzle pressure for the 1-1/4” tip

 

Stacked Smoothbore Tips

A common smooth bore nozzle used on a 2-1/2” handline is the triple stack tips. It has three actual tip sizes in a stack just like a master stream. The sizes are 1”, 1-1/8” and 1-1/4”. The easiest way to list the pump discharge pressure for a line using this nozzle is to calculate the line using the highest flow tip which is the 1-1/4”. No matter which tip is being used always calculate for the 1-1/4” tip. There is a good chance that the pump operator will not know which tip is being used any way. If a lower tip size is used the flow and nozzle pressure will only increase slightly and still fall within the guidelines for the nozzles capabilities.  Listed below is a chart that reflects this.

 

 

1-1/4” tip  328 GPM

1-1/8” tip  295 GPM

1”tip        260 GPM   

 

Gated Wye Evolutions

 

Using a gated wye on a handline evolution is accomplished the same way as the handline that is put together on the fire scene with a couple of little differences. The friction loss in the feeder line going to the wye is going to be calculated for the total water that is delivered through all the handlines that are connected to the gated wye. For example, let’s say there are two

1-3/4” lines connected to the gated wye with each of them flowing 150 GPM. That means that a total of 300 GPM is going through the feeder line that goes from the engine to the gated wye. Therefore the friction loss calculation will be for 300 GPM. As far as calculating for the small handlines connected to the gated wye, basically the calculation is made for a single line even though there are two or more connected. This holds true whether all the small handlines connected to the wye are equal or not. If they are not equal calculate for the highest pressure line. Here’s an example of what would be on the pump chart.

 

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Friction Loss For 100‘ Sections Of Hose

 

1-3/4” @ 150 GPM     25 psi

2-1/2” @ 250 GPM     15 psi

2-1/2” @ 300 GPM     20 psi

2-1/2” @ 325 GPM     25 psi

5”     @ 1000 GPM    5 psi

    GPM  100’     200’    300’      400’     500’

2-1/2”   300   20 psi   40 psi   60 psi   80 psi          100 psi

Plus the required pressure for the 1-3/4” hose and the nozzle pressure.

 

Master Stream Operations

 Img_4779FIRERESCUERS

 

First I would like to talk about master stream basics to establish a base of information to so that the method for determining pump discharge pressures can be better understood. Here is a basic definition of a master stream. A master stream is a heavy caliber stream delivered through a master stream water delivery appliance. A master stream is used when flows surpass 350 GPM becoming too difficult to be delivered from a handline operation due to nozzle reaction. The stream that a master stream operation produces is high in flow and usually in the form of a straight stream using a smooth bore tip or some type of combination nozzle.

 

There are three types of master stream operations, the fixed master stream, the portable master stream and the elevated master stream. The following information about master stream smooth bore tips can be found in most fire stream management books in circulation today. It’s information that needs to be understood to establish a base to operate from.

Smooth Bore Tips

The most common set of smooth bore tips that come with a master stream is what is known as the stacked tips. The stacked tips gets its name because it consists of four tips connected into one stack, which is then attached to the master stream appliance. The tip sizes and the corresponding flows are based on an 80 PSI NP.

 

1-3/8” – 502 GPM

1-1/2” – 598 GPM

1-3/4” – 814 GPM

2” –     1063 GPM

 

For master stream appliances capable of flowing 2000 GPM the following tip sizes with 80 PSI nozzle pressures will apply. Again these are the most common.

 

2-1/4” 1345 GPM

2-1/2” 1661 GPM

2-3/4” 2010 GPM

 

It should be noted that the standard rule on smooth bore tip nozzle pressures used with master stream operations is to use a nozzle pressure of

80 PSI. Nozzle pressures higher than this will create a broken and insufficient stream, as well as an unstable operation in the elevated and portable modes according to most fire stream books.

 

Now that you have read this information I would like you to keep an open mind about the following information on smooth bore tip operations. At no time does any of the operations in this document break the rules that the manufacturers of all equipment involved have set.

 

One Pump Discharge Pressure With Smooth Bore Tips In Conjunction With Master Streams

 

Master stream operations using smooth bore tips can deliver several different flows with each potentially having a different pump discharge pressure. It is not practical to list all of them on the pump chart The only pressure that needs to be listed is the pump discharge pressure for the maximum flow operation with the most common flow being 1000 GPM with a 2” tip at 80 psi NP. With portable and elevated operations this holds true for the supporting discharge evolutions needed to deliver the water to the appliance. When using smooth bore nozzles, the maximum flow pump discharge pressure listed on the pump chart will work with any size tip from 2” down to 1” and still provide for a safe and efficient operation. Yes the rated flow at the standard smooth bore nozzle pressure (80 PSI) will probably be surpassed. However it will do this while keeping within the required inlet pressure of the appliance (200 psi) and the maximum allowed flow and nozzle reaction.

 

Based on a 2″ tip flowing 1060 GPM @ 80 psi NP.

 

                     1-3/8″ tip 589 GPM    110 psi NP

                     1-1/2″ tip  634 PGM    90 psi NP

                     1-3/4″ tip  814 GPM    80 psi NP

                     2″ tip        1060 GPM  80 psi NP        

 

Here is an example of what would be on the pump chart.

 

Portable Master Stream

This Chart Is For All Tip Sizes

GPM          100’   200’          300’    400’     500’

5”   1000 5 psi  10 psi  15 psi  20 psi  25 psi

Plus 80 psi nozzle pressure and 15 psi appliance friction loss

 

High Pressure Smooth Bore Tip Operations

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The following operations can be used with fixed, elevated, and portable master stream operations.

 

High pressure smooth bore tip operations have been around for decades however most firefighters have either never heard about it or have been told that it is a counter productive and dangerous operation.

The purpose of high pressure smooth bore tip operations used in conjunction with a master stream is to provide the required GPM to extinguish the fire problem with a high velocity stream that improves the reach and penetration capabilities of the firefighting stream itself while still maintaining efficient stream performance.

The maximum allowed nozzle pressure for this type of operation in a fixed, portable or elevated master stream operation is based on the following rules.

 

1. Maximum allowed inlet pressure to the master stream appliance. The three most common manufacturers of the master stream appliance for the municipal fire service are; Task Force Tips, Akron Brass and Elkhart Brass. Listed below are the specs for each of the three brands of these appliances.

 

Task Force Tips 200 PSI inlet pressure

Akron Brass 200 PSI inlet pressure

Elkhart Brass 200 PSI inlet pressure

 

I think you will find that most of the other master stream manufactures require the same 200 psi inlet pressure as well. Always make sure the inlet pressure is never exceeded when performing high pressure operations.

 

2. Maximum allowed flow for the master stream appliance.

3. Maximum allowed nozzle reaction for the master stream appliance. This is based on a 100 psi combination nozzle at the rated flow of the appliance.

1250 GPM  631 lbs. NR

1500 GPM  758 lbs. NR

2000 GPM  1010lbs. NR

4. Maximum allowed operating pressure for the discharge hose supplying the master stream appliance when applicable. This applies to elevated stream operations using a non-quint truck company and portable master stream operations.

5. Stream angle capabilities for the appliance/apparatus combination in the elevated and portable mode.

 

In order to provide the required pressure for the high pressure operation the pump operator needs to understand the limitations mentioned above and throttle up accordingly. Flow tests will determine what the maximum pressure can be, again based on the above mentioned criteria. A pump chart should than be designed showing all possible pump operations that can be used. The pump operator should plan on throttling up to the maximum allowed pre-determined pressure unless something stops him. Does this mean that every time a deck gun operation is placed into service the pump discharge pressure needs to be maxed out? No. The pre-determined pump discharge pressure is the number that the pump operator will try to reach unless something stops him. A high percentage of the time tips up to 1-½” can be pumped up to 200 psi pump discharge pressure

 

Some of the things that may stop the operation from going to maximum pressure are:

 

1-run out of water

2-run out of throttle

3-run out of RPMs

4-the stream accomplishes its goal

5-other rules set by the department and the incident.

 

HIGH FLOW/ HIGH VELOCITY OPERATIONS

The following smooth bore tip sizes with their corresponding nozzle pressure and flows have successfully produced high velocity/high flow streams using a master stream. The maximum nozzle reaction for a 1250 GPM appliance is 631 LBS and for a 2000 GPM appliance, 1010 LBS.


 

1250 GPM Appliance

1-3/8″ tip @ 175 psi NP = 743 GPM 519 NR

1-1/2” tip @ 150 PSI NP = 817 GPM 530 NR

1-3/4” tip @ 120 PSI NP = 996 GPM 577 NR

2” tip @ 100 PSI NP = 1189 GPM 628 NR

 

 

2000 GPM Appliance

2” tip @ 140 PSI NP = 1407 GPM 879 NR

2” tip @ 150 PSI NP = 1455 GPM 942 NR

2” tip @ 160 PSI NP = 1500 GPM 1005 NR

 

It should be noted that the 2” tip at 160 PSI NP has produced a stream with a footprint reaching 360 feet.

 

LOW FLOW/HIGH VELOCITY OPERATIONS

Picture a large fire that has totally consumed the structure ending up with a large pile of burning rubble left to be overhauled? This is where the digging power of a high velocity stream can really have a positive effect. The following smooth bore tip sizes and corresponding nozzle pressures and flows have been successfully used in this type of operation. One point to remember is that the goal in this type of operation is to produce velocity, not high flows.

 

1-1/8” tip up to 180 PSI NP = 504 GPM

1-1/4” tip up to 180 PSI NP = 623 GPM

1-3/8” tip up to 180 PSI NP = 754 GPM

 2-37

This deck gun is using a 1-1/4” smooth bore tip flowing 623 GPM at

180 PSI NP.

 

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2000 GPM APPLIANCE AND WATERWAY ON AN ELEVATED PLATFORM WITH A 2″ TIP

165 NP     1527 GPM         220′ REACH       1005 NR

  

 

Elevated master streams you have to follow the guidelines for flowing water at specific angles.  This information is always found on a placard on the turntable console.


Here is an example of what would be on the pump chart

 

Fixed Master Stream With Smooth Bore Tips

1-3/8”, 1-1/2”, and 1-3/4” tips    200 psi PDP

2” tip                                   140 psi PDP

 

Combination Nozzles

 

The same concept described with the smoothbore tips in regards to pumping the highest flow also applies to combination nozzles as well.

Selectable Gallonage Nozzle

The pump discharge pressure should be established for the highest flow in the flow range of the nozzle. If for whatever reason a lower flow in the flow ranges selected there will only be a slightly elevated nozzle pressure, nozzle reaction, and flow which will be well within the guidelines for the operations.

Fixed Gallonage Nozzle

The pump discharge pressure should be established for the rated flow of the nozzle. If for whatever reason the flow should be less than what the nozzle is rated at the reach of the fire stream will decline. Whether or not the reach will be good enough is based on the actual fire ground scenario.

Automatic Nozzle

For a large flow operation the pump discharge pressure should be established for the highest rated flow. If the flow rate is not achievable the automatic nozzle will adjust its pressure to whatever flow is being delivered while maintaining optimum stream performance.


Building Fire Protection Systems

highrise

A building fire protection system is a plumbing system within a structure designed to deliver water to be used for fire suppression within its confines.

The water supply is provided either by the system water supply, which is plumbed into a municipal water source, or by FD pumping apparatus connected to a water source. The final discharging of the water is accomplished through strategically installed sprinkler heads and/or fire department attack lines via standpipe hose connections.

 

The following information is the basic codes set forth by

N.F.P.A. 14 2010 Edition  outlining pressure limitations for building fire protection systems that have a direct effect on how the fire department delivers water within the structure.

 

 

System hydrostatically tested at no less than 200 psi.

 

For a system pressure of 150 psi or higher the hydrostatic test will be no less than 50 psi higher than the system pressure.

 

The maximum allowed system pressure is no higher than 350 psi.

Express standpipes can exceed 350 psi.

Buildings with a single pump as well as express standpipes for multiple pumps can exceed 350 psi to meet the standards on tall buildings.

 

There are two basic sets of standards that have been put out by NFPA that effect water delivery. The first standard was in place until 1993 and the second standard which is still in place started at 1993. Please note that structures with the Pre 93 standards were not required to upgrade to the Post 93 standards.

PRE 1993 The minimum requirement for water delivery is 500 GPM at 65 psi standpipe residual pressure at the highest standpipe outlet in the system. The pressure restricting device has a minimum allowed residual pressure at the standpipe outlet at of 100 psi. The pressure reducing valve has a maximum static pressure of 175 psi at the standpipe outlet.

POST 1993 The current code requires the same 500 GPM flow but the minimum residual pressure was increased to 100 psi. The pressure restricting device pressure setting of 100 psi is not required and the pressure reducing valve static pressure setting remains at 175 psi.

 

Sprinkler Systems

 

Pump operations for building sprinkler systems are basic. The system itself is rated at 200 psi and the pump discharge pressure for the operation is 150 psi. It is important to remember that the 150 psi needs to be maintained. With the possibility of additional heads activating after the 150 pressure is established, the RPM’s may need to be increased via the throttle to maintain the pressure. Here is an example of what would be on the pump chart.

Sprinkler Systems

Maintain 150 psi.

 

Multi Story Building Fire Protection System With No Building Pump

 

Lowrise building standpipe systems without a system pump, whether they are standpipes only or combination systems, can be found in lowrise structures. These systems can be either wet or dry. If the system is wet it is supplied from municipal water which does not nessacerily provide enough pressure to support handlines. And of course if it is dry the FD pumping apparatus needs to provide all the pressure. It is the responsibility of the FD pumping apparatus to increase the system pressure to the required pressure to support the handlines deployed by the firefighters.

Throughout the years the pump discharge pressure for a system like this was always calculated using fireground hydraulics. Let’s see what the requirements were.

25 psi for the standpipe

 

5 psi for each floor

 

Pressure requirements for the handline which includes friction loss for the hose and the nozzle pressure

 

Friction loss in the lines supplying the FDC from the pumper

 

The following questions must be answered for the formula to work.

 

Does the pump operator know what floor the handline or handlines are connected on?

 

Does the pump operator know how many handlines are being used?

 

Does the pump operator know the makeup of the handline (length, diameter, nozzle pressure, and GPM)?

 

In the real world of firefighting there is a good chance that the poor pump operator will not have all the answers. Additionally, formulas can create answers that will be hard to find on a standard pumper 10 psi increment discharge gauge.

 

The alternative is to pump a maximum pressure, 200 psi.

Here’s why. The 200 psi number is based on the maximum allowed system pressure There is no guessing, the 200 psi gives the firefighters maximum pressure which in turn will provide maximum flow. If the pressure/flow is excessive the firefighter can control it by gating the standpipe outlet valve.

 

There is a good chance that the PDP developed from the hydraulic formula will be close to 200 psi anyway

 

Example

                           EVOLUTION

Three story building with fire on the third floor

150’ of 1-3/4” hose with a 100 psi automatic nozzle  flowing 150 GPM

CALCULATIONS

10 psi for elevation

150 psi for the 1-3/4” handline

25 psi for the standpipe

Negligible for the lines supplying the FDC

Total 185 psi

 

Here is an example of what would be on the pump chart.

 

Standpipe System With No Building Pump

Maintain 200 psi

Multi Story Building fire protection system with a building pump

If the fire department needs to pump the system in a high-rise building, it will have to match the building pump pressure and possibly exceed it.

Explanation: there are one-way check valves located where the FDC enters into the system and after the building pump on the discharge pipe both on the discharge side of the building pump. Because of these one-way check valves, if the pump is running but not doing the job (producing the pressure or GPM) the only way the fire department can enter into the system to take over is to exceed the building pump pressure. Either the building system pressure does the job, or the fire department pumper. As a rule they do not work together. If the building pump is not running there will still be system head pressure up against the check valve that will have to be overcome by the engine companies.

If the building pump should fail to provide the required pressure for whatever reason, the fire department pumper will still have to pump the system as though the fire problem is on the roof Yes, the highest pressure. The reason for this is simple. A building fire pump does not have the capability of controlling its engine pressure over a wide pressure range as would be needed to provide the proper pressure to all the floors in a multi-story building. Therefore, the building pump is designed to pump to the highest point in the building. Because of the potential of high pump pressures in the system, there needs to be a way to reduce the pressure at the lower floors to provide the proper pressure to the handlines. This is done through a different types of pressure regulating devices. The PRV is designed to reduce the building pressure to the proper pressure on the floor it is in service on.

Two Pump Discharge Pressures

After all lines are connected, the system pressure should be determined and the engine pressure of the pumper supplying the system should be set at 50 psi below the system pressure. Setting the FD pumper engine pressure 50 psi below the building system pressure will allow the building pump to stay running and do the job as long as it can. A pressure drop in the system of more than 50 psi is a good indication of a substantial amount of water flowing which in turn is a good indication of a drop in residual pressure that could affect the flow to the handlines. It might also be an indication of pump failure. It’s at this point the FD pumpers should take over the building system.

Once the fire department pumper is set up and pumping its required engine pressure, it should be determined whether or not the pumper is flowing water into the system. At any time the pumper should start flowing water, whether it be initially after the pumper goes into operation or at any time during the incident, or if the firefighters inside request more pressure, immediately PUMP THE SYSTEM PRESSURE.

Below is an example of a supplemental chart listing all building system pressures.

BUILDING FIRE PROTECTION SYSTEM PRESSURES

BUILDING – (ENGINES)

SYSTEM PRESSURE

STARTING ENGINE PRESSURE

 

Allure Condos (3)

330 psi

320 psi

 

Atrium Building (2)

135 psi

85 psi

 

 

Relay Pump Operations

DSC00025

 

Relay pumping is a pump operation that has been with the fire service for years. A relay pump operation is a supply line evolution that is required when there is not enough pressure from the water source to move the required volume of water to the fire through the supply hose. This operation requires a pumper to be connected into the supply line evolution at the water source to boost the pressure in the supply line high enough to move the water to the pumper at the fire. This holds true for long and short distance operations.

 

Developing the required pump discharge pressure is simple. When the units are hooked up and ready to flow water the line is charged under low pressure. Basically treat it like you would charging a supply line from a hydrant. Once the line is charged the pumper at the water source throttles up to an initial pressure to give the receiving pumper enough water to get started. I like starting at about 120 psi. Once the pump operator at the receiving end starts flowing he can communicate to the pump operator at the water source and advise him if more pressure is needed. Here is an example of what the pump chart should look like.

Relay Pump Operation.

Start at 120 psi.

 

The following chart shows how far a single pumper can move specific amounts of water. Based on these statistics a decision can be made on how many pumpers will be needed in a relay. This can also be placed on a pump chart.

4”

  500’                     1400 GPM

1000’              950 GPM

1500’              750 GPM

2000’              650 GPM

2500’              600 GPM

3000’              500 GPM

 

Pump Chart

Friction Loss For 100‘ Sections Of Hose

 

1-3/4” @ 150 GPM     25 psi

2-1/2” @ 250 GPM     15 psi

2-1/2” @ 300 GPM     20 psi

2-1/2” @ 328 GPM     25 psi

5”      @ 1000 GPM    5 psi

 

1-3/4” Preconnect

1-3/4” 150 GPM Handline X 200’ With A TFT Automatic 100 psi Nozzle

150 psi PDP

 

2-1/2” Preconnect

2-1/2” 328 GPM Handline X 200’ with a 1-1/4” Smooth bore 50 psi Nozzle

100 psi PDP

 

Gated Wye

    GPM  100’     200’    300’      400’     500’

2-1/2”   300   20 psi   40 psi   60 psi   80 psi          100 psi

Plus the required pressure for the 1-3/4” hose and the nozzle pressure.

 

2-1/2” Handline Made Up

   GPM   100’     200’    300’      400’         500’

2-1/2”  328    25 psi   50 psi   75 psi   100 psi     125 psi

Plus 50 psi for the nozzle pressure for the 1-1/4” tip

 

Relay Pump Operation.

Start at 120 psi.

Pumper Placement For A Relay Pump Operation

4”

 500’               1400 GPM

1000’              950 GPM

1500’              750 GPM

2000’              650 GPM

2500’              600 GPM

3000’              500 GPM

 

Portable Master Stream

This Chart Is For All Tip Sizes

GPM          100’   200’         300’    400’     500’

5”    1000 5 psi  10 psi  15 psi  20 psi  25 psi

Plus 80 psi nozzle pressure and 15 psi appliance friction loss

 

Automatic Nozzle @ 1000 GPM

140 psi

 

Elevated Stream (Quint)

200 psi

 

 Fixed Master Stream

1-3/8”, 1-1/2”, and 1-3/4” tips    200 psi PDP

2” tip                                   140 psi PDP

 

Sprinkler System

Maintain 150 psi

 

Standpipe System With No Building Pump

Maintain 200 psi

 

Standpipe System With A Building Pump

 

BUILDING FIRE PROTECTION SYSTEM PRESSURES

BUILDING –

SYSTEM PRESSURE

STARTING ENGINE PRESSURE

 

Allure Condos

330 psi

320 psi