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Bartow Fire DepartmentBartow Fire Department

Essentials Fourth Edition:

Chapter 11 – Water Supply {pages 379-393} {skill sheet 394}

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Introduction• We continue to develop new methods and

materials for extinguishing fires

• Water still remains the primary extinguishing agent because of its universal abundance and ability to absorb heat

• Two primary advantages of water is that it can be conveyed long distances and it can be easily stored

• Thus, the fundamental principles of a water supply system

• Because it is our main extinguishing agent, we need to understand water supply systems

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Principals of Municipal Systems• They provide the methods for supplying water to

populated areas

• As population increases, communities seek to improve water distribution systems from reliable sources

• Water departments may be separate, city operated utility, or a regional or private water authority

• The principal function is to provide potable water

• The water department’s are the experts in water supply problems and the fire department must work with them in planning fire protection coverage

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Principals of Municipal Systems• Their officials should realize that we are vitally

concerned with water supply and work with them on water supply needs and locations and types of fire hydrants

• Water systems are basically composed of the following fundamental components:

1. Source of Water Supply

2. Means of Moving Water

3. Water Processing or Treatment Facilities

4. Water Distribution System, Including Storage

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Sources of Water Supply

• Can be either surface water or ground water

• Most systems are supplied from only one source, but there are instance where both sources are used

• Two examples of surface water supply are rivers and lakes

• Ground water examples can be wells or water producing springs

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Sources of Water Supply

• Engineering estimates are done to determine the amount of water that a community needs

• This is a total amount of domestic and industrial use plus firefighting use

• In cities, the domestic / industrial requirements far exceed the amount for firefighting use

• In small towns, the reverse is more often the case

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Means of Moving Water• There are three methods of moving water in a

system

• Direct Pumping System

• Gravity System

• Combination System

• We will cover each method individually

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Direct Pumping System• These use one or more pumps that take water from

the primary source and discharge it through the filtration and treatment processes

• From there a series of pumps force the water into the distribution system

• If purification is not needed, the water can pumped directly into the distribution system from the primary source

• Failures in supply lines and pumps can usually be overcome by duplicating these units and providing a secondary power source

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Gravity System• Uses a primary water source located at a higher

elevation than the distribution system

• The gravity flow from the higher elevation provides the water pressure

• This is usually only sufficient when the primary water source is located a least several hundred feet higher than the highest point in the distribution system

• Most common examples are a mountain reservoir that supplies water to a city below or a system of elevated tanks in a city

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Combination System• This is what most communities use

• The gravity is supplied by elevated storage tanks

• The tanks serve as emergency storage and provide adequate pressure through the use of gravity

• When system pressure is high, or during times of low consumption, automatic valves open and fill the tanks

• When the pressure drops during heavy consumption, the valves open and provide extra water and pressure via the elevated storage

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Combination System• Providing a good combination system involves

reliable, duplicated equipment and proper sized storage containers that are strategically located

• Elevated storage can also ensure water if the system becomes otherwise inoperative

• Storage should be sufficient to provide domestic and industrial demands plus the demands expected in firefighting operations

• Should also be sufficient to permit making most repairs, alterations, or addition to the system

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Combination System

• Location of storage and capacity of the mains leading from the storage are also important factors

• Many industries will provide their own private system and make it available to the fire department

• Water may be available to some communities from storage systems such as cisterns that are considered a part of the distribution system

• The FD removes the water from the sources by drafting

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Processing / Treatment Facilities

• Treatment of water is a vital process

• This removes contaminates that may be detrimental to the health of those who drink or use it

• Can be treated by coagulation, sedimentation, filtration, or the addition of chemicals, bacteria, or other organisms

• Additives such as fluoride or oxygen can also be introduced into the water at this time

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Processing / Treatment Facilities• Our concern is that a maintenance error, natural

disaster, loss of power, or fire, could disable the pumping station{s} or hamper the purification

• Any of these would drastically reduce the volume and pressure available for firefighting

• Another issue could be the inability of a treatment system to process water fast enough to meet demand

• Either way, we must have plans in place to deal with these potential shortfalls

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Distribution System• This is the part that receives the water from the

pumping station and delivers it throughout the area served

• The ability to deliver an adequate quantity of water relies upon the carrying capacity of the system’s network of pipes

• The flow of water through these pipes cause friction that results in a loss of pressure

• This loss is much less where hydrants are supplied from two or more directions

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Distribution System• A hydrant that gets water from only one

direction is known as a dead-end hydrantdead-end hydrant

• If it gets water from two or more directions, it is called a circulating feed or looped linecirculating feed or looped line

• A distribution system that provides a circulating feed from several mains is called a grid systemgrid system

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Grid System• Should consist of the following components:

• Primary Feeders:Primary Feeders: Large pipes with relatively widespread spacing, that convey large quantities of water to various points of the system for local distribution to the smaller mains

• Secondary Feeders:Secondary Feeders: Network of intermediate sized pipes that reinforce the grid within the various loops of the primary feeder system and aid the concentration of required fire flow at any point

• Distributors:Distributors: Grid arrangement of smaller mains serving individual fire hydrants and blocks of consumers

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Grid System• Two or more primary feeders should run from

the source of supply to the high risk and industrial districts of the community via different routes

• Secondary feeders should be arranged in loops as far as possible to give two directions of supply to any point

• This will increase the capacity of the supply at any point and ensure that a break in a feeder main will not completely cut off the supply

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Grid System• In residential areas, the recommended size for

hydrant mains is at least 6 inches in diameter

• These should be closely gridded by 8 inch cross connecting mains at intervals of not more than 600 feet

• For business / industrial, the minimum recommendation is 8 inch mains with cross connectors at least every 600 feet

• 12 inch mains should be used on principal streets and in long mains not cross connected frequently

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Water Main Valves• These provide a way to control the flow of water

through the distribution system

• They should be located at frequent intervals in the grid so that only small districts are cut off when necessary

• All valves should be operated at least once a year to keep them in good condition

• Actual need of valve usage may be very infrequent so they must be maintained

• Good spacing guarantees only short sections of pipe will be out of service when necessary

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Water Main Valves• An important facet of the supply system is the

ability to promptly operate the valves during an emergency

• A well managed utility will have locations of all valves on record

• They should be inspected and operated on a regular basis

• If the fire department is aware of the locations, their condition and accessibility can be checked during pre planning and any problems directed to the water department

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Water Main Valves• Broadly divided between indicating and non-

indicating types

• Indicating valves visually show whether the gate or valve seat is open, closed, or partially closed

• Private fire protection system valves are normally the indicating type

• Two common types of indicator valves are the Post indicator valve {PIV} and the Outside screw and yoke {OS&Y} valve

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Water Main Valves• A PIV is a hollow metal post that is attached to

the valve housing with a stem inside showing the words open or shut, thus letting us know the position of the valve

• The OS&Y has a yoke on the outside with a threaded stem that controls the opening or closing of the valve

• The threaded portion of the stem is out of the yoke when the valve is open and inside the yoke when the valve is closed

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Water Main Valves• Non-indicating valves are normally buried or

placed in manholes

• If a buried valve is properly installed, it can be operated above ground through a valve box

• You need a special socket {valve} wrench on the end of a reach rod to operate the valve

• These valves can be either gate valves or butterfly valves

• They can be indicating or non-indicating

• They are usually a non-rising type – the valve is turned and the gate controls water flow with

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Water Main Valves• Gate valves should be marked with a number

indicating the number of turns necessary to completely close the valve

• If you meet resistance before you have reached the indicated number, it usually means there is debris or other obstruction in the valve

• Butterfly valves are tight closing and usually have a rubber or rubber composition seat that is bonded to the valve body

• This valve disk rotate 90 degrees from the fully open to the tight shut position

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Water Main Valves• A non-indicating butterfly valve will require a

valve key

• Its principle of operation provides satisfactory water control after long periods of inactivity

• Advantages of proper valve installation are readily apparent

• If they are installed according to established standards, only one or two hydrants should be out of service with a single break is being repaired

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Water Main Valves• This advantage is quickly lost if valves are not

properly maintained or not fully open

• Friction loss increases greatly when valves are only partially open

• This closed or partially closed valve may not be an issue during ordinary domestic flow periods

• Suddenly when fire flows are needed, the required amount of water is not there

• There will be a problem meeting fire flows in areas with closed or partially closed valves

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Water Pipes• Generally made of cast iron, ductile iron, asbestos

cement, steel, plastic, or concrete

• The type of pipe installed needs to be the proper type for the soil conditions and pressures it will be exposed to

• When installed in unstable or corrosive soils, or difficult access areas, steel or reinforced concrete may be need to give the strength needed

• Some examples may be: under railroads and highways, industrial machinery areas, earthquake areas, or areas with rugged terrain

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Water Pipes• A pipe’s internal surface, regardless of material,

will create friction loss

• Some materials create less than others

• Engineers should determine the best type of pipe for the conditions to be encountered

• Other factors can also affect flow rates and friction loss

• Encrustation of minerals inside the pipe and sedimentation that settles out of he water can both increase friction loss and reduce rate of flow

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Kinds of Pressure• Pressure, when talking about fluids, has a very

broad meaning• Pressure is defined as force per unit area

{which we usually express as pounds per square inch}

• In the fire service, pressure is most commonly thought of as the velocity of water in a conduit {pipe or hose} of a certain size

• We must have an understanding of the following terms which are critical to the fire service

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Kinds of Pressure• Terms to Remember:

• Static Pressure

• Normal Operating Pressure

• Residual Pressure

• Flow Pressure

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Static Pressure • This is stored pressure, {the water is not

moving} or the potential energy available to force water through pipe, fittings, fire hose, and adapters

• True static pressure is rarely found in a supply system so they use a different term in supply system application

• In those cases, static pressure is defined as the normal pressure existing on a system before a flow hydrant is opened

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Normal Operating Pressure

• This is the pressure found in a distribution system during periods of normal consumption demand

• Water flow in a distribution system fluctuates constantly

• This is an average of the total amount of water used each day during a one year period

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Residual Pressure

• This is the pressure left in a distribution system at a specific location when a quantity of water is flowing

• This is the part of the total available pressure that is not used to overcome friction or gravity while forcing water through pipe, fittings, fire hose, or adapters

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Flow Pressure

• This is the forward velocity of a steam of water that is read using a pitot tube and gauge

• It is the forward velocity pressure at a discharge opening, either at a hydrant discharge or a nozzle discharge orifice while water is flowing.

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Fire Hydrants• Two main types of fire hydrants are the dry barrel

and the wet barrel

• Dry barrel hydrants are used where freezing weather is expected and is usually classified as a compression, gate, or knuckle-joint type that open either with pressure or against pressure

• The actual valve is well below ground – below the anticipated frost line for this geographic location

• When closed, the barrel from the top to the valve should be empty

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Dry Barrel Hydrants• After use, valve is closed, and the barrel drains

through a small drain at the bottom of the hydrant near the main valve

• This feature is very important in determining usability

• The drain is open when the hydrant is closed and vice versa

• If hydrant is not completely open, the drain is partly open

• This can result to ground erosion and is the impetus for opening and closing hydrants completely

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Dry Barrel Hydrants• A hydrant’s ability to drain may be tested as

follows:

• Flow some water, close and cap all discharges except one

• Place your hand over the discharge, you should feel a slight vacuum pulling your palm toward the discharge

• If you do not feel the vacuum, notify the water department because the drain is probably plugged

• If this is a cold climate, pump the hydrant dry!

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Wet Barrel Hydrants• May only be used in areas that do not have

freezing weather

• Usually have a compression type valve at each outlet or they may have only one valve in the bonnet that controls the flow of water to all outlets

• Hydrant is always filled with water toe the valves

• In general, all hydrant bonnets, barrels, and foot pieces are made of cast iron

• The working parts are usually made of bronze, but valve facings may be rubber, leather, or composition materials

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Wet Barrel Hydrants

• Hydrant flow will vary based on many factors

• The proximity of feeder mains and the size of the mains to which the hydrant is connected have a major impact on the flow

• Sedimentation and deposits in the system may increase friction loss

• This may occur over time so older system may experience a decline in available flow

• Better fire attack / tactics decisions can be made if we know the amount of water flow available

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Hydrants – Color Coding• This is the NFPA system to let us know how much

water is available from a fire hydrant

• There are local variations – the main intent is so firefighters can estimate available water supply

NFPA COLOR CODING SYSTEM

• Class AAClass AA Light Blue 1,500 gpm & moreLight Blue 1,500 gpm & more

• Class AClass A GreenGreen 1,000 – 1,499 1,000 – 1,499 gpmgpm

• Class BClass B OrangeOrange 500 – 999 gpm 500 – 999 gpm

• Class CClass C RedRed < 500 gpm < 500 gpm

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Location of Hydrants• Installation of hydrants is usually performed by

water department personnel but the location, spacing, and distribution of the hydrants should be the responsibility of the fie chief or fire marshal

• Hydrants should not be spaced more than 300 feet apart in high value districts

• A basic rule is to place on hydrant near each street intersection and intermediate hydrants where distances between intersections exceed 350 to 400 feet

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Location of Hydrants

• This represents a minimum requirement and should only be used as a guide for spacing hydrants

• Other factors more pertinent to the particular locale include types of construction, types of occupancy, congestion, the sizes of water mains, required fire flows, and pumping capacities

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Inspection & Maintenance• In most places, this is the responsibility of the

water department because they are in a better position to do this work than other agencies

• In many cases however, FD personnel do flow testing and inspections

• Here are some potential problems you need to look for when you are checking fire hydrants:

• Obstructions such as sign posts, utility poles, or fences too close to the hydrant that will interfere with hydrant to pumper connections

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Inspection & Maintenance• Here are some potential problems you need to

look for when you are checking fire hydrants:

• Make sure the outlets face the proper direction for hook up and that there is sufficient clearance between the outlets and the ground for connection

• Is the hydrant damaged due to vehicle crashes?

• Is the hydrant rusting or corroded?

• Are the caps stuck in place with paint?

• Is the operating stem easily turned?

• Any obstructions inside the hydrant {bottles, rocks, cans} that may restrict flow?

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Pitot Gauge Use• If you assist in hydrant testing or inspections,

you will need to use a pitot tube to measure the flow coming from a hydrant

• There are two methods of holding it properly

• The first is to grasp the tub just behind the blade with the first two fingers and thumb of the left hand while the right hand holds the air chamber

• The little finger of the left hand rests upon the hydrant outlet or nozzle to steady the instrument

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Pitot Gauge Use• Another way is to have the fingers of the left hand

split around the gauge outlet and left side of the fist placed on the edge of the hydrant orifice or outlet

• The blade is then sliced into the stream in a counterclockwise direction

• The right hand steadies the air chamber

• There are fixed mount version available for hydrant tests that reduce the chance of human error

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Alternative Water Supplies• We should not limit our studies of water

supplies to the piped public distribution system

• We need to understand there are other water supplies available in case of system failure or a fire so large that we need more water than the system can deliver

• Know where you can go to draft water – You need to be able to get your truck to the source and have enough water there to use, and if it is private property, permission to use it

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Alternative Water Supplies• When drafting, almost any static source of water

can be used

• The depth for drafting water is an important operational consideration

• Silt and debris can render a source useless by clogging strainer, by seizing or damaging pumps, and by allowing sand and small rocks to enter attack lines and clog fog steam nozzles

• You should use a strainer on your drafting hose

• The suction hose should be located and supported so the strainer does not rest on or near the bottom

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Alternative Water Supplies

• A depth of 24 inches of water both above and below the strainer is a good guideline

• Special low profile strainers can draft in as little as 1 – 2 inches of water

• We should try to identify, mark, and record alternative water supply sources in pre planning

• You also need to consider what effect the weather {drought / flood} will have on the amount of water available and the accessibility to it

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Rural Water Supply Operations

• These operations consist of mobile water supply apparatus shuttles and relay pumping

• These require pre planning and practice to succeed

• The necessary resources must be dispatched promptly and an ICS / IMS system implemented for control and coordination

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Water Shuttles• This is the hauling of water from a supply source

to portable tank, where the water is drafted to fight a fire

• Shuttles are recommended for distances greater than ½ mile or anytime the distance from the source to the fire is more than the hose on the truck

• Get the tankers / tenders moving early if you think you will need them

• The key to these operations are fast fill / fast dump times

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Water Shuttles

• There should be water supply officers at the draft site and the dump site

• If personnel are available, consider assigning someone to traffic control, hydrant operation, hook up operations, tank venting, or any other job where a person doing it would speed up the ops.

• This leaves the drivers in their vehicles, increasing both speed and safety

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Water Shuttles• Three key components to water shuttle

operations:

1. Attack apparatus at the Fire

2. Fill Apparatus at the Fill Site

3. Mobile water supply apparatus to haul water from the fill site to the dump site

• Dump site is generally located near the fire

• It consists of one or more portable water tanks into which the haulers dump their water

• A drafting / attack engine can then draw from these tanks as needed

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Water Shuttles• Low level intake devices permit use of most of

the water in these tanks

• If large fire flows are needed, multiple portable tanks are needed and the number of haulers has to increase also

• When using multiple tanks, a jet siphon will maintain the water level in one tank for the pumper, while the haulers dump into the others

• A jet siphon uses a 1.5” discharge line connected to the siphon and then attached to the hard suction between two tanks

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Water Shuttles• Plain siphons or commercial tank connecting

devices are sometimes used although they are not generally as efficient as jet siphons

• Most common type of portable reservoir is the collapsible or folding style using a square metal frame and a synthetic or canvas duck liner

• There is also a round, synthetic tank with a floating collar that rises as the tank is filled, making it self supporting

• Try to mount them so that they are easily removed from the apparatus

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Water Shuttles• You should place a heavy tarp on the ground

before you place you portable tank out, this is to help protect the liner

• Try to position the tank so that is allows easy access from multiple directions but does not inhibit the access of other apparatus to the scene

• If more than one hauler is there, empty one completely, send it for water, then start emptying the next one

• This helps keep traffic sequenced at the fill site and the dump site

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Water Shuttles• Four basic methods for tankers to unload water:

1. Gravity dumping through large {10 – 12 inch} dump valves

2. Jet dumps that create a venturi effect increasing the flow rate

3. Apparatus mounted pumps that off load the water

4. Any combination of the above methods

• NFPA 1901 requires apparatus on level ground to be able to dump or fill at rates of at least 1,000 gpm

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Water Shuttles• Those flows necessitate adequate tank venting

and openings in baffles

• Pumping of the water needs to be done by a trained apparatus driver / operator

• Gravity dumps may be activated by a firefighter, which relieves the driver from exiting cab and saves time in the overall process

• In order to fill quickly, use the best fill site available, large or multiple hose lines, or place a pumper at the site to speed the process

• Try to arrange the site so backing is minimal

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Relay Pumping

• If your water source is close enough, relay pumping may be considered

• Two important factors for relay operations:

1. The water supply must be capable of maintaining the desired volume of water required for the duration of the incident

2. The relay must be established quickly to be worthwhile

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Relay Pumping• Number of pumpers needed and distance between

them is determined by several factors such as volume of water needed, distance between the source and the fire scene, hose size available, amount of hose available, and pumper capacities

• THE APPARATUS WITH THE GREATEST THE APPARATUS WITH THE GREATEST PUMPING CAPACITY SHOULD BE PUMPING CAPACITY SHOULD BE LOCATED AT THE WATER SOURCELOCATED AT THE WATER SOURCE

• LDH or multiple lines increase the distance and volume that a relay can supply due to less friction loss

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Relay Pumping• Water supply officer needs to be appointed to

determine the distance between pumpers and to coordinate water supply operations

• The WSO must make a calculation to determine the distance between pumpers

• It is important to know the friction loss at particular flows for the size hose being used

• These can be made into a chart and place on the truck for quick reference

• Plan your relay ops in advance and practice them during training

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NOT a good example of DraftingNOT a good example of Drafting

THE THE

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