Water

1. Water

2. Knowledge Objectives • Describe the properties of water. • Describe the three sources of water. • Describe water’s role in extinguishing a fire. • Describe static water pressure. • Describe residual water pressure. • Describe flow pressure.

3. Skills Objectives • Operate a hydrant. • Shut down a hydrant. • Demonstrate how to obtain the static pressure. • Demonstrate the correct use of a Pitot gauge.

4. Introduction • Water supply must be dependable and adequate for fire suppression • Ensuring a dependable water supply is a critical operation to be accomplished as soon as possible. • Water is obtained from one of two sources: • Municipal and private water systems • Static water systems

5. Chemical Properties of Water(1 of 7) • 70–75% of the earth’s surface is covered by water. • Abundance means it is easy to take for granted. • U.S. Geological Survey says U.S. population consumes 408 billion gallons of water per day. • Water is a virtually colorless, odorless, and tasteless liquid.

6. Chemical Properties of Water(2 of 7) • Many hidden qualities contained in the chemical description H2O • One atom of oxygen bound by two atoms of hydrogen attached on the same side • Opposite electrical charges attract each other, making water molecules stick to each other. • Surface tension allows water to flow, puddle, or remain together even after leaving the nozzle.

7. Chemical Properties of Water(3 of 7)

8. Chemical Properties of Water(4 of 7) • Water dissolves more substances than any other liquid because of the strong bond between hydrogen and oxygen. • As water passes through or moves by a substance, molecular charges take chemicals, minerals, and solvents with it. • Substance dissolving into water is determined by whether the substance’s components can break water’s hydrogen bond.

9. Chemical Properties of Water(5 of 7) • Water has been used as the primary extinguishing agent in the fire service from the earliest days because of its availability. • Water can also absorb heat because of its hydrogen-bonding characteristics. • Water absorbs almost five times more heat than sodium bicarbonate.

10. Chemical Properties of Water(6 of 7) • Physical properties of water • Water exists in all three property states: liquid, gas, and solid. • Water is the primary substance used to extinguish fire because it turns to vapor (steam) when it comes in contact with fire.

11. Chemical Properties of Water(7 of 7) • Harmful characteristics of water • Pure H2O has a relatively low ability to conduct electricity. • Turbidity is the amount of particulate matter suspended in water. • Particulates settling in the pump housing and water tank cause a breakdown of valves, gaskets, seals, and piping, which can lead to leaks and operational deficiencies.

12. Municipal Water Systems(1 of 3) • Make clean water available to people in populated areas • Provide water for fire protection • Owned and operated by local government agency (city, county, special water district) • Some municipal water systems are privately owned.

13. Municipal Water Systems(2 of 3) • Municipal water is supplied to homes, commercial establishments, and industries. • Hydrants make the water supply available to the fire department. • Most automatic sprinkler systems and standpipe systems are connected to a municipal source.

14. Municipal Water Systems(3 of 3) • Three parts • Water source • Treatment plant • Distribution system

15. Water Sources • Municipal systems draw water from wells, rivers, streams, lakes, and reservoirs. • Many systems draw water from several sources to ensure a sufficient supply. • Systems have storage facilities to ensure they will meet the demands of the area if the primary water source is interrupted. • Backup supply can provide water for months or years.

16. Water Treatment Facilities • Remove impurities • Water that is clean and clear from the source requires little treatment. • Some facilities use chemicals to remove impurities and improve the water’s taste. • Chemicals are also used to kill bacteria and harmful organisms.

17. Water Distribution System(1 of 6) • Delivers water from the treatment facility to end users and hydrants through water mains • Distribution center includes pumps, storage tanks, and reservoirs to ensure the required water can be delivered where and when it is needed and at a required pressure. • Pressure requirements differ depending on water use. • Systems rely on pumps to provide the required pressure directly or indirectly.

18. Water Distribution System(2 of 6) • Pure gravity-feed system • Water source, treatment plant, and storage facilities on high ground while end users live in lower-lying areas • May not require any pumps because gravity provides the pressure necessary to deliver the water • Pumps may be used to deliver water from a treatment plant to elevated water storage towers or reservoirs on hills or high areas.

19. Water Distribution System(3 of 6)

20. Water Distribution System(4 of 6) • Combination pump-and-gravity-feed system • Must maintain enough water in elevated storage tanks and reservoirs to meet anticipated demands • Underground water mains that deliver water to end users come in different sizes. • Large mains: primary feeders that carry large quantities of water to a town or city • Smaller mains: secondary feeders that distribute water to smaller areas • Smallest pipes: carries water to users or hydrants

21. Water Distribution System(5 of 6) • Size of water mains depends on the water needed for normal consumption and fire protection • Most jurisdictions specify a minimum size main that can be installed to ensure adequate flow. • A well-designed water main system follows a grid pattern. • Grid provides water flow to fire hydrant from multiple directions

22. Water Distribution System(6 of 6) • Control valves installed at intervals throughout the distribution system allow sections to be turned off or isolated. • Shut-off valves are located where underground mains meet distributor pipes. • Can be closed to prevent further water flow

23. Flow and Pressure(1 of 8) • To understand procedures for hydrant testing, fire fighters must understand terminology. • Flow or quantity of water moving through a pipe, hose, or nozzle is measured by its volume. • Usually given in terms of gallons (or liters) per minute • Water pressure refers to an energy level, measured in psi (or kPa). • Volume and pressure are two different, but mathematically related, measurements.

24. Flow and Pressure(2 of 8) • Water not moving has potential energy • Water that is moving has potential and kinetic energy. • Static pressure is the pressure in the system when water is not moving. • Causes water to flow out an opened hydrant • Created by elevation pressure and/or pump pressure

25. Flow and Pressure(3 of 8) • Static pressure is measured by placing a pressure gauge on a hydrant port and opening the hydrant valve. • The normal operating pressure is the amount of pressure in a system during a period of normal consumption. • Fire fighters need to know how much pressure is in the system when a fire occurs.

26. Flow and Pressure(4 of 8) • Residual pressure • Pressure in the system when water is flowing • Best indicates how much more water is in the system • The more water flowing, the less residual pressure

27. Flow and Pressure(5 of 8) • Fire fighters use the difference between static and residual pressure to determine how many attack lines or appliances can be operated from the available supply. • Tables developed to help calculate the maximum amount of available water • Flow pressure measures the quantity of water flowing through an opening during a hydrant test.

28. Flow and Pressure(6 of 8) • To calculate the volume of water flowing, measure the pressure at the center of the water stream passing through an opening and factor in the orifice’s size and flow characteristics. • Pascal’s law: pressure acts in all directions equally • Bernoulli’s equation: defines friction loss as a drop in pressure while water maintains velocity

29. Flow and Pressure(7 of 8) • Knowing static pressure, flow in GPM (L/min), and residual pressure lets the fire fighter calculate water that can be obtained from hydrant or hydrants on the same water main. • Gravity exerts its effects on flowing water based on the stream’s elevation and altitude. • Elevation is the position of the pump (above or below) compared to the nozzle. • Atmospheric pressure changes depending on location.

30. Flow and Pressure(8 of 8) • Water hammer • Pressure surge or wave from kinetic energy of fluid in motion when forced to stop or change direction suddenly • Quickly closing valves, nozzles, or hydrants can create damaging pressure spikes. • Liquid is not compressible. • Any energy applied to it is instantly transmitted back through it.

31. Fire Hydrants(1 of 6) • Hydrants provide water for firefighting. • Public hydrants are part of a municipal system and draw water from public water mains. • Hydrants on private water systems are supplied by a municipal system or a separate source. • Identify source, adequacy, and reliability of supply to ensure hydrants will be sufficient

32. Fire Hydrants(2 of 6) • Most hydrants consist of a barrel attached to an underground water distribution system. • Hydrants are equipped with one or more valves to control water flow through the hydrant. • One or more outlets connect the fire department hoses to the hydrant.

33. Fire Hydrants(3 of 6) • Dry-barrel hydrants are used where temperatures fall below freezing. • Valve controlling water flow into the barrel is located at the base, below the frost line • Barrel length depends on climate and depth of valve • Water enters the barrel only when it will be used. • When not in use, the barrel must stay dry.

34. Fire Hydrants(4 of 6) • Dry-barrel hydrants (continued) • A partially opened valve means the drain is also partially open and pressurized water can flow out. • Most dry-barrel hydrants have only one large valve controlling water flow. • Trash or foreign objects in empty dry-barrel hydrants can obstruct water flow or damage the fire department pumper.

35. Fire Hydrants(5 of 6) • Wet-barrel hydrants are used where temperatures do not drop below freezing. • Always have water in the barrel • Not drained after each use • Wet-barrel hydrants have separate valves to control flow to each outlet.

36. Fire Hydrants(6 of 6) Courtesy of American AVK Company

37. Operation of Fire Hydrants • Fire fighters must be proficient in operating a hydrant. • Individual departments may vary procedures for opening a hydrant. • Follow SOPs for your department.

38. Shutting Down a Hydrant • Shutting down a hydrant properly is just as important as opening a hydrant properly. • Hydrant damaged during shutdown cannot be used until it is repaired

39. Locations of Fire Hydrants(1 of 2) • Hydrants are located according to local standards and nationally recommended practices. • May be placed a certain distance apart • Every 500’ (152 m) in residential areas • Every 300’ (91 m) in high-value commercial and industrial areas

40. Locations of Fire Hydrants(2 of 2) • Some requirements for locating hydrants are based on building occupancy, construction, and size. • Builder may have to install additional hydrants so no part of the building is more than a specified distance from the closest hydrant. • Knowing the plan for installing hydrants makes them easier to find in emergencies.

41. Inspecting and Maintaining Fire Hydrants (1 of 5) • Hydrants are essential to fire suppression efforts so fire fighters must understand how to inspect and maintain them. • Check hydrants regularly. • During inspections, fire fighters may encounter common problems and should know how to correct them.

42. Inspecting and Maintaining Fire Hydrants (2 of 5) • Check for visibility and accessibility. • Hydrants should be visible from every direction. • Bright reflective colors are effective. • Should not be hidden by tall grass, brush, fences, debris, dumpsters, or other obstructions • No vehicles should be allowed to park in front of a fire hydrant. • Should be installed at an appropriate height above the ground

43. Inspecting and Maintaining Fire Hydrants (3 of 5)

44. Inspecting and Maintaining Fire Hydrants (4 of 5) • Check the exterior for signs of damage. • Open the steamer port of a dry-barrel hydrant to ensure the barrel is dry and free of debris. • Make sure all caps are present and outlet hose threads are in good working order.

45. Inspecting and Maintaining Fire Hydrants (5 of 5) • Ensure the hydrant is working properly. • Open the valve wide enough to ensure that water flows out and flushes debris out of the barrel. • After flushing, shut down the barrel. • When a hydrant is fully drained, replace the cap on the wet-barrel hydrant. • Check gaskets in gaps to make sure they are not cracked, broken, or missing.

46. Testing Fire Hydrants(1 of 5) • Water that is available to fight a fire at a location is crucial in planning an attack. • Fire companies are often assigned to test hydrant flow. • Testing procedures are simple but require a basic understanding of hydraulics and careful attention to detail.

47. Testing Fire Hydrants(2 of 5) • Fire hydrant testing procedure • Requires two adjacent hydrants, a Pitot gauge, and an outlet cap with a pressure gauge • Place the cap gauge on one outlet of the first hydrant. • Open the valve to let water fill the hydrant barrel. • Record the initial pressure reading on the gauge as static pressure.

48. Testing Fire Hydrants(3 of 5)

49. Testing Fire Hydrants(4 of 5) • Fire hydrant testing procedure (continued) • At the second hydrant, remove one discharge cap and open the hydrant. • Use the size of the discharge opening (usually 2½” [51 mm]) and Pitot pressure to calculate the flow or look it up in a table. • Devices are available to simplify the process of taking accurate Pitot readings.

50. Testing Fire Hydrants(5 of 5)