Introduction

2. 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

3. 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

4. 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: • Source of Water Supply • Means of Moving Water • Water Processing or Treatment Facilities • Water Distribution System, Including Storage

5. 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

6. 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

7. 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

8. 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

9. 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

10. 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

11. 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

12. 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

13. 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

14. 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

15. 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

16. Distribution System • A hydrant that gets water from only one direction is known as a dead-end hydrant • If it gets water from two or more directions, it is called a circulating feed or looped line • A distribution system that provides a circulating feed from several mains is called a grid system

17. Grid System • Should consist of the following components: • 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: 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: Grid arrangement of smaller mains serving individual fire hydrants and blocks of consumers

18. 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

19. 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

20. 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

21. 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

22. 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

23. 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

24. 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

25. 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

26. 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

27. 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

28. 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

29. 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

30. 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

31. Kinds of Pressure • Terms to Remember: • Static Pressure • Normal Operating Pressure • Residual Pressure • Flow Pressure

32. 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

33. 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

34. 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

35. 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.

36. 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

37. 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

38. 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!

39. 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

40. 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

41. 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 AA Light Blue 1,500 gpm & more • Class A Green 1,000 – 1,499 gpm • Class B Orange 500 – 999 gpm • Class C Red < 500 gpm

42. 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

43. 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

44. 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

45. 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?

46. 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

47. 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

48. 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

49. 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

50. 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