Download ppt - Pumping Apparatus Driver/Operator — Lesson 6 Pumping Apparatus Driver/Operator Handbook, 2 nd Edition Chapter 6 — What Is Water and Where Does It Come

Pumping Apparatus Driver/Operator — Lesson 6

Pumping Apparatus Driver/Operator Handbook, 2nd Edition

Chapter 6 — What Is Water and Where Does It Come From?

Pumping Apparatus Driver/Operator6–2

Learning Objectives

1.Select facts about the characteristics of water.

2.List the ways in which water has the ability to extinguish fire.

3.Answer questions about specific heat.

4.Select facts about latent heat of vaporization.

(Continued)


Learning Objectives

5.Calculate latent heat of vaporization.

6.Answer questions about the surface area of water.

7.Explain the ways in which water smothers fire.

8.Select facts about specific gravity. (Continued)


Learning Objectives

9.List advantages of water as an extinguishing agent.

10. List disadvantages of water as an extinguishing agent.

11. Distinguish between pressure and force.

12. Explain how force is determined.(Continued)


Learning Objectives

13. State the principles of fluid pressure.

14. Match to their definitions terms associated with pressure.

15. Explain how to measure atmospheric pressure.

16. Calculate head pressure. (Continued)


Learning Objectives

17. List causes of friction loss in fire hose.

18. List causes of friction loss in piping systems.

19. List the principles of friction loss.

20. Answer questions about other factors affecting friction loss.

(Continued)


Learning Objectives

21. List ways to reduce friction loss.

22. Select facts about water hammer.

23. Name the four primary components of a municipal water system.

24. Answer questions about the primary components of a municipal water system.

(Continued)


Learning Objectives

25. Select facts about water main valves.

26. Answer questions about water pipes.

27. Match to their definitions water system consumption rates.

28. Select facts about private water supply systems. (Continued)


Learning Objectives

29. List the purposes of a private water supply system.

30. List the advantages to have separate piping arrangements in a private water supply system.


Characteristics of Water

• Water is a compound of hydrogen and oxygen formed when two hydrogen atoms (H2) combine with one oxygen atom (O).

• Between 32ºF and 212ºF (0ºC and 100ºC), water exists in a liquid state.

(Continued)



• Below 32º F (0ºC) (the freezing point of water), water converts to a solid state called ice.

• Above 212ºF (100ºC) (the boiling point of water), water converts into a gas called water vapor or steam; it cannot be seen.

(Continued)



(Continued)



• Water is considered to be incompressible, and its weight varies at different temperatures.

Note: Water is measured in pounds per cubic foot (kg/L)

(Continued)



• Water is heaviest close to its freezing point, weighing approximately 62.4 lb/ft3 (1 kg/L)

• Water is lightest close to its boiling point, weighing approximately 60 lb/ft3 (0.96 kg/L)

• For fire protection purposes, ordinary fresh water is generally considered to weigh 62.5 lb/ft3 or 8.33 lb/gal (1 kg/L)


Ways in WhichWater Extinguishes Fire

• Cooling– By absorbing heat from the fire

• Smothering– Water can be used to smother fires in combustible

liquids whose specific gravity is higher than 1.– Smothering also occurs to some extent when

water converts to steam in a confined space.


Specific Heat

• The heat-absorbing capacity of a substance

• Amounts of heat transfer are measured in British thermal units (Btu) or joules (J)– A Btu is the amount of heat required to raise the

temperature of 1 pound of water 1ºF.– The joule has taken the place of the calorie

(1 calorie = 4.19 joules).

(Continued)


Specific Heat

• Is the ratio between the amount of heat needed to raise the temperature of a specified quantity of a material and the amount of heat needed to raise the temperature of an identical quantity of water by the same number of degrees.

• Of different substances varies. Refer to Table 6.1 on p. 136 of the manual.


Latent Heat of Vaporization

• Is the quantity of heat absorbed by a substance when changing from liquid to vapor.

• The temperature at which a liquid absorbs enough heat to change to vapor is known as its boiling point. At sea level, water begins to boil or vaporize at 212ºF (100ºC).

(Continued)



• Vaporization does not completely occur the instant water reaches the boiling point.

• Each pound of water requires approximately 970 Btu (1 023 kJ) of additional heat to convert completely to steam.

(Continued)



• The latent heat of vaporization is significant in fire fighting because the temperature of the water is not increased beyond 212ºF during the absorption of the 970 Btu for every pound of water.


Surface Area of Water

• The speed with which water absorbs heat increases in proportion to the water surface exposed to the heat.

(Continued)



• Water expands when converted to steam. At 212ºF (100ºC), water expands approximately 1,700 times its original volume.

(Continued)



• Steam expansion is rapid inside a burning building. The use of a fog stream in a fire attack requires that adequate ventilation be provided ahead of the hoseline.


Ways in Which Water Smothers Fire

• By floating on liquids– Water floats on liquids that are heavier than

water.

– If the material is water soluble, the smothering action is not likely to be effective.

• By forming an emulsion– Water smothers fire by forming an emulsion

over the surface of certain combustible liquids.(Continued)


Ways in WhichWater Smothers Fire

• By forming an emulsion– When a spray of water agitates the surface, the

agitation causes the water to be suspended in emulsion bubbles on the surface; the emulsion bubbles smother the fire.

– Emulsion bubbles can only form when the combustible liquid has sufficient viscosity – the tendency of a liquid to possess internal resistance to flow.


Specific Gravity

• The density of liquids in relation to water

• Water is given a value of 1. Liquids with a specific gravity less than 1 are lighter than water and float on water. Those with a specific gravity greater than 1 are heavier than water and sink to the bottom.

• Most flammable liquids have a specific gravity of less than 1.


Advantages of Water asan Extinguishing Agent

• Water has a greater heat-absorbing capacity than other common extinguishing agents.

• A relatively large amount of heat is required to change water to steam. This means that more heat is absorbed from the fire.

(Continued)



• The greater the surface area of water exposed, the more rapidly heat is absorbed. The exposed surface are of water can be expanded by using fog streams or deflecting solid streams off objects.

(Continued)



• Water converted into steam occupies 1,700 times its original volume.

• Water is plentiful, relatively inexpensive, and readily available in most jurisdictions.


Disadvantages of Water asan Extinguishing Agent

• Water has a high surface tension and does not readily soak into dense materials. However, when wetting agents are mixed with water, the water’s surface tension is reduced and its penetrating ability is increased.

• Water may be reactive with certain fuels such as combustible metals.

(Continued)



• Water has low levels of opacity and reflectivity that allow radiant heat to easily pass through it.

• Water readily conducts electricity, which can be hazardous to firefighters working around energized electrical equipment.

(Continued)



• Water freezes at 32ºF (0ºC), which is a problem in jurisdictions that frequently experience freezing conditions. Water freezing poses a hazard to firefighters by coating equipment, roofs, ladders, and other surfaces. In addition, ice forming in and on equipment may cause it to malfunction.


Pressure vs. Force

• Pressure– Force per unit area

– May be expressed in pounds per square foot (psf), pounds per square inch (psi), or kilopascals (kPa)

• Force– A simple measure of weight

– Is usually expressed in pounds or kilograms


Determining Force(Customary System)

• The weight of 1 cubic foot of water is approximately 62.5 pounds.

• Because 1 square foot contains 144 square inches, the weight of water in a 1-square-inch column of water 1 foot high equals 62.5 pounds divided by 144 square inches

62.5 / 144 = 0.434 pounds

(Continued)


Determining Force(Customary System)

(Continued)


Determining Force (Customary System)

• A 1-square-inch column of water 1 foot high exerts a pressure at its base of 0.434 psi.

• The height required for a 1-square-inch column of water to produce 1 psi at its base equals 1 foot divided by 0.434 psi/ft.

• Therefore, 2.304 feet of water column exerts a pressure of 1 psi at its base.


Determining Force(Metric System)

• A cube that is 0.1 m x 0.1 m x 0.1 m (a cubic decimeter) holds 1 liter of water.

• The weight of 1 liter of water is 1 kilogram.

• The cube of water holds 1 000 liters of water and weighs 1 000 kg.

(Continued)


Determining Force(Metric System)

• Because the cubic meter of water is comprised of 100 columns of water, each 10 decimeters tall, each column exerts 10 kPa at its base.


Principles of Fluid Pressure

• First Principle — Fluid pressure is perpendicular to any surface on which it acts.

(Continued)



• Second Principle — Fluid pressure at a point in a fluid at rest is the same intensity in all directions.

(Continued)



• Third Principle — Pressure applied to a confined fluid from without is transmitted equally in all directions.

(Continued)



• Fourth Principle — The pressure of a liquid in an open vessel is proportional to its depth.

(Continued)



• Fifth Principle — The pressure of a liquid in an open vessel is proportional to the density of the liquid.

(Continued)



• Sixth Principle — The pressure of a liquid on the bottom of a vessel is independent of the shape of the vessel.


Terms Associated with Pressure

• Atmospheric pressure — Pressure exerted by the atmosphere at sea level (14.7 psi [101 kPa])

• psig — Pounds per square inch gauge; actual atmospheric pressure = gauge reading

• psia — Pounds per square inch absolute; the psi above a perfect vacuum, absolute zero

(Continued)



• Vacuum — Any pressure less than atmospheric pressure

• Perfect vacuum — Absolute zero pressure

• Negative pressure — Gauge readings of less than 0 psi or kPaNote: The term negative pressure is technically a misnomer.

(Continued)



• Head — The height of a water supply above the discharge orifice

• Head pressure — The result of dividing the number of feet that the water supply is above the discharge orifice by 2.304

• Static pressure — Stored potential energy available to force water through pipe, fittings, fire hose, and adapters (Continued)



• Static — At rest or without motion

• Normal operating pressure — That pressure found in a water distribution system during normal consumption demands

• Residual pressure — That part of the total available pressure not used to overcome friction loss or gravity while forcing water through pipe, fittings, fire hose, and adapters

(Continued)



• Residual — A remainder or that which is left

• Flow pressure (velocity pressure) — That forward velocity pressure at a discharge opening while water is flowing

• Elevation — The center line of the pump or the bottom of a static water supply source above or below ground level (Continued)



• Altitude — The position of an object above or below sea level

• Pressure loss — When a nozzle is above the pump

• Pressure gain — When the nozzle is below the pump

(Continued)



• Elevation pressure — Another term for both pressure loss and pressure gain

• Friction loss — That part of the total pressure lost while forcing water through pipe, fittings, fire hose, and adapters


Measuring Atmospheric Pressure

• Compare the weight of the atmosphere with the weight of a column of mercury.

Example: A pressure of 1 psi (6.9 kPa) makes the column of mercury about 2.04 inches (52 mm) tall. At sea level, the column of mercury is 2.04 x 14.7, or 29.9 inches (759 mm) tall.


Causes of Friction Loss in Fire Hose

• Movement of water molecules against each other

• Linings in fire hose

• Couplings

• Sharp bends

• Change in hose size or orifice by adapters

• Improper gasket size


Causes of Friction Loss in Piping System

• Movement of water molecules against each other

• Inside surface of the piping– The rougher the inner surface of the pipe, the

more friction loss

• Pipe fittings

• Bends

• Control valves


Principles of Friction Loss

• First Principle — If all other conditions are the same, friction loss varies directly with the length of the hose or pipe.

(Continued)



• Second Principle — When hoses are the same size, friction loss varies approximately with the square of the increase in the velocity of the flow.

(Continued)



• Third Principle — For the same discharge, friction loss varies inversely as the fifth power of the diameter of the hose

• Fourth Principle — For a given flow velocity, friction loss is approximately the same, regardless of the pressure on the water.


Other FactorsAffecting Friction Loss

• Water is practically incompressible. The same volume of water supplied into a fire hose under pressure at one end will be discharged at the other end.

• Friction loss in a system increases as the length of hose or piping increases.

• Flow pressure is greatest near the supply source and lowest at the farthest point in the system. (Continued)



• When the valve on the nozzle end of a hose is opened, water flows moderately at a low pressure. If the opening is made directly at the hydrant, the flow will be much greater at a higher pressure.

• Decreasing the amount of water flowing through a hose reduces the speed of the water in the hose; less friction loss occurs.

(Continued)



• If velocity is increased beyond practical limits, the friction becomes so great that resistance agitates the entire stream, creating critical velocity. Beyond this point, it becomes necessary to parallel or siamese hoselines to increase the flow and reduce friction.


Ways to Reduce Friction Loss

• Minimize sharp bends or kinks in the hose by using proper hose handling techniques.

• Reduce the length of the hose or increase its diameter.


Water Hammer

• Suddenly stopping water moving through a hose or pipe results in an energy surge being transmitted in the opposite direction, often at many times the original pressure. This surge is referred to as water hammer.

• Water hammer can damage the pump, appliances, hose, or the municipal water system itself.

(Continued)


Water Hammer

(Continued)


Water Hammer

• Always open and close nozzle controls, hydrants, valves, and hose clamps slowly to prevent water hammer.

• Apparatus inlets and remote outlets should be equipped with pressure relief devices to prevent damage to equipment.

• High-volume systems should be protected with dump valves.


Primary Components ofMunicipal Water Systems

• Source of water supply

• Means of moving water

• Water processing or treatment facilities

• Water distribution system, including storage


Source of Water Supply

• The primary water supply can be obtained from either surface water or groundwater.

• Although most water systems are supplied from only one source, there are instances where both sources are used.


Means of Moving Water

• Direct pumping system– Uses one or more pumps to take water from the

primary source and discharge it through the filtration and treatment processes

– Includes a series of pumps that then forces the water into the distribution system

(Continued)



(Continued)



• Gravity system– Uses a primary water source located at a higher

elevation than the distribution system– Works best when the primary water source is

located at least several hundred feet (meters) higher than the highest point in the water distribution system

(Continued)



(Continued)



• Combination system– Is a combination of a direct pumping system and a

gravity system– Includes elevated storage tanks to supply the

gravity flow

(Continued)




Water Processing or Treatment Facilities

• The treatment of water for the water supply system is a vital process.

• Water is treated to remove contaminants that may be detrimental to the health of those who use or drink it.

(Continued)


Water Processing orTreatment Facilities

• The main concern regarding treatment facilities is that a maintenance error, natural disaster, loss of power supply, or fire could disable the pumping station(s) or severely hamper the purification process. Any of these situations would drastically reduce the volume and pressure of water available for fire fighting operations.


Water Distribution System,Including Storage

• The distribution system is the part that receives the water from the pumping station and delivers it throughout the area served.

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

(Continued)


Water Distribution System, Including Storage

• When water flows through pipes, its movement causes friction that results in a reduction of pressure. There is much less pressure loss in a water distribution system when fire hydrants are supplied from two or more directions.

(Continued)



• A fire hydrant that receives water from only one direction is known as a dead-end hydrant.

(Continued)



• A fire hydrant that receives water from two or more directions is called a circulating feed or a looped line.

(Continued)



• A distribution system that provides circulating feed from several mains constitutes a grid system, consisting of the following components:– Primary feeders– Secondary feeders– Distributors

(Continued)



(Continued)



• Primary feeders — Large pipes with widespread spacing that convey large amounts of water to various points of the system for local distribution to 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 the required fire flow

(Continued)



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

(Continued)



• To ensure sufficient water, two or more primary feeders should run from the source of supply to the high-risk and industrial districts of the community by separate routes.

(Continued)



• In residential areas, the recommended size for fire hydrant supply mains is at least 6 inches (150 mm) in diameter. These should be closely gridded by 8-inch (200 mm) cross-connecting mains at intervals of not more than 600 feet (180 m)

(Continued)



• In the business and industrial districts, the minimum recommended size is an 8-inch (200 mm) main with cross-connecting mains every 600 feet (180 m)

(Continued)



• Twelve-inch (300 mm) mains may be used on principal streets and in long mains not cross-connected at frequent intervals.

• Water mains as large as 48 inches (1.2 m) may be found in major cities.


Water Main Valves

• The function of a valve in a water distribution system is to provide a means for controlling the flow of water through the distribution piping.

• Valves should be located at frequent intervals so that only small districts are cut off if it is necessary to stop the flow at specified points.

(Continued)


Water Main Valves

• Valves should be operated at least once a year to keep them in good condition.

• One of the most important factors in a water supply system is the water department’s ability to promptly operate the valves during an emergency or breakdown of equipment.

(Continued)


Water Main Valves

• Indicating valves– Shows whether the gate or valve seat is open,

closed, or partially closed

– Are the most commonly used valves in private fire protection systems

(Continued)


Water Main Valves

• Indicating valves– Post indicator valve (PIV) —

A hollow metal post attached to the valve housing. The valve stem inside has the words OPEN and SHUT printed so that the valve position is shown.

(Continued)


Water Main Valves

• Indicating valves– Outside screw and yoke

(OS&Y) — Has a yoke on outside with threaded stem that controls gate’s opening or closing. The threaded part of the stem is out of the yoke when the valve is open and inside the yoke when the valve is closed.

(Continued)


Water Main Valves

• Nonindicating valves– Are buried or installed in manholes

– Are the most common types of valves used on most public water distribution systems


Water Main Valves

• Control valves– Gate valves

– Butterfly valves

(Continued)


Water Main Valves

• If valves are installed according to established standards, it normally will be necessary to close off only one or perhaps two fire hydrants from service while a single break is being repaired. This cannot occur unless valves are properly maintained and kept fully open.

(Continued)


Water Main Valves

• High friction loss is caused by valves that are only partially open. A fire department will experience difficulty in obtaining water in areas where there are closed or partially closed valves in the distribution system.


Water Pipes

• Water pipe that is used underground is generally made of cast iron, ductile iron, asbestos cement, plastic, or concrete.

• The internal surface of the pipe, regardless of the material from which it is made, offers resistance to water flow.

• Friction loss is increased by encrustation of minerals on the interior surfaces of the pipe.


Water System Capacity

• Average daily consumption (ADC) — The average of the total amount of water used in a water distribution system over the period of one year

• Maximum daily consumption (MDC) — The maximum total amount of water that was used during any 24-hour interval within a 3-year period (Continued)


Water System Capacity

• Peak hourly consumption (PHC) — The maximum amount of water used in any1-hour interval over the course of a day


Private Water Supply Systems

• Private water supply systems are most commonly found on large commercial, industrial, or institutional properties.

• Private water supply systems may service one large building or a series of buildings on the complex.

(Continued)



• Purposes– To provide water strictly for fire protection

purposes

– To provide water for sanitary and fire protection purposes

– To provide for fire protection and manufacturing processes

(Continued)



• The design of private water supply systems is typically similar to that of municipal systems.

• Most private water supply systems separate piping for fire protection and domestic/ industrial services.

(Continued)



• Advantages:– The property owner has control over the water

supply source.– Either of the systems are unaffected by service

interruptions to the other system.


Summary

• All pumping apparatus driver/operators should – Understand the properties of water as a

fire extinguishing agent– Know the factors that influence its delivery

during a pumping operation– Be thoroughly familiar with the operation of

the apparatus to which they are assigned(Continued)


Summary

• Fire department personnel must also be familiar with the design and reliability of both public and private water supply systems in their jurisdiction.

(Continued)


Summary

• Large, well-maintained systems may provide a reliable source of water for fire protection purposes. Small capacity, poorly maintained, or otherwise unreliable private water supply systems should not be relied upon to provide all the water necessary for adequate fire fighting operations.


Discussion Questions

1.How does water have the ability to extinguish fire?

2.What is specific heat?

3.What is the latent heat of vaporization?

4.How does water smother fire?

5.What is specific gravity?(Continued)



6.What are the advantages of water as an extinguishing agent?

7.What are the disadvantages of water as an extinguishing agent?

8.What is pressure?

9.What is force?

(Continued)



10. How is force determined?

11. What are the principles of fluid pressure?

12. How do you measure atmospheric pressure?

13. What are some causes of friction loss in fire hose? (Continued)



14. What are some causes of friction loss in piping systems?

15. What are the principles of friction loss?

16. Name ways to reduce friction loss.

17. What is water hammer?

18. Name the four primary components of a municipal water system.