Fire Detection and Suppression

1
Fire Detection and Suppression

• Chapter 3
• Water Supply

2
Characteristics of Water

• Compound of two parts hydrogen and one part
  oxygen (H20)
• Liquid between 32?F and 212?F (0?C and 100?C)
• Solid below 32F (0?C)
• Gas above 212F (100C)
• Incompressible
• Weight for fire protection purposes62.5 lb/ft3
  or 8.33 lb/gal (1 kg/L)

3
Extinguishing Properties of Water

• The law of specific heat the specific heat of
  any substance 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.
• (Continued)

4
Extinguishing Properties of Water (cont.)

• The law of latent heat of vaporization
• The latent heat of vaporization is the quantity
  of heat absorbed by a substance when it changes
  from a liquid to a vapor.
• 1 gallon of water will absorb 9,346 Btu (1,266
  8,080) of heat if all the water is converted to
  steam.
• (Continued)

5
Extinguishing Properties of Water (cont.)

• Surface area of water the speed with which water
  absorbs heat increases in proportion to the water
  surface exposed to the heat.
• Expansion ability
• Smothering ability
• (Continued)

6
Extinguishing Properties of Water (cont.)

• Specific gravity the density of liquids in
  relation to water
• Liquids with a specific gravity less than 1 are
  lighter than water and therefore float on water.
• Most flammable liquids have a specific gravity of
  less than 1.

7
Waters Advantages as an Extinguishing Agent

• Greater heat-absorbing capacity
• Large amount of heat required to change water
  into steam
• Easily expanded surface area
• Plentiful supply

8
Waters Disadvantages as an Extinguishing Agent

• High surface tension
• Reactivity
• Low levels of opacity and reflectivity
• Freezes at 32?F (0?C)
• Conductivity

9
Water Pressure and Velocity

• Pressure force per unit area on a liquid or gas
  expressed in psi or kPa
• Force simple measure of weight
• Velocity
• The speed at which fluid travels through hose or
  pipe
• Result of pressure exerted on the fluid at its
  source
• (Continued)

10
Water Pressure and Velocity (cont.)

• Principles of pressure
• First Principle fluid pressure is perpendicular
  to any surface on which it acts.
• Second Principle fluid pressure at a point in a
  fluid at rest is the same intensity in all
  directions.
• Third Principle pressure applied to a confined
  fluid from without is transmitted equally in all
  directions.
• (Continued)

11
Water Pressure and Velocity (cont.)

• Principles of pressure
• Fourth Principle the pressure of a liquid in an
  open vessel is proportional to its depth.
• Fifth Principle the pressure of a liquid in an
  open vessel is proportional to the density of the
  liquid.
• Sixth Principle the pressure of a liquid on the
  bottom of a vessel is independent of the shape of
  the vessel.
• (Continued)

12
Water Pressure and Velocity (cont.)

• Types of pressure
• Atmospheric pressure pressure exerted on the
  earth by the atmosphere itself
• Head pressure
• Height that a pressure can lift a column of
  liquid
• Height of a water supply above the discharge
  orifice is called the elevation head.
• Static pressure stored potential energy
  available to force water through pipe, fittings,
  fire hose, and adapters
• (Continued)

13
Water Pressure and Velocity

• Types of pressure (cont.)
• Normal operating pressure 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
• Flow pressure (velocity pressure) forward
  velocity pressure while water is flowing

14
Pressure Loss and Gain

• Elevation
• Center line of the pump or the bottom of a static
  water supply source above or below ground level
• Elevation pressure results from differences in
  elevation of nozzle and pump.
• Altitude
• Position of an object above or below sea level
• Effects of lower atmospheric pressure on drafting
  above 2000 feet (600 m)

15
Friction Loss

• That part of the total pressure lost while
  forcing water through pipe, fittings, fire hose,
  and adapters
• (Continued)

16
Friction Loss (cont.)

• Causes
• Movement of water molecules against each other
• Linings in fire hose/inside surface of piping
• Hose couplings/pipe fittings
• Sharp bends
• Change in hose size or in orifice by adapters
• Improper hose-coupling gasket size/pipe control
  valves

17
Friction Loss (cont.)

• 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.
• Second principle when hoses are the same size,
  friction loss varies approximately with the
  square of the increase in the velocity of the
  flow.
• Third principle for the same discharge, friction
  loss varies inversely as the fifth power of the
  diameter of the hose.
• (Continued)

18
Friction Loss

• Principles of friction loss (cont.)
• Fourth principle for a given flow velocity,
  friction loss is approximately the same,
  regardless of the pressure on the water.
• Other factors affecting friction loss diameter
  and length of hose or pipe
• Reducing friction loss

19
Water Hammer

• Energy surge that results from suddenly stopping
  or starting water moving through hose or pipe
• Can damage the pump, appliances, hose, or the
  municipal water system itself

20
Municipal Water Supply Systems

• Components
• Source of water supply
• Means of moving water
• Water processing or treatment facilities
• Water distribution system, including storage
• (Continued)

21
Municipal Water Supply Systems (cont.)

• Sources of water supply
• Public water supply system
• Surface or ground water
• Means of moving water
• Directing pumping system
• Gravity system
• Combination system
• (Continued)

22
Municipal Water Supply Systems (cont.)

• Water processing or treatment facilities
• The fire departments main concern regarding
  treatment facilities is that a maintenance error,
  natural disaster, loss of power supply, or fire
  could drastically reduce the volume and pressure
  of water available for fire fighting operations.
• (Continued)

23
Municipal Water Supply Systems (cont.)

• Water Distribution System
• Dead-end hydrants
• Circulating feed or looped lines
• Grid system
• Primary feeders
• Secondary feeders
• Distributors

24
Water Distribution System Variables

• Piping materials
• Pipe diameter
• Piping arrangement
• Simple loop
• One inflow point and one outflow point.
• Exactly two paths between the inflow and outflow
  points.
• (Continued)

25
Water Distribution System Variables

• Piping arrangement (cont.)
• Complex loop (grid)
• More than one inflow point
• More than one outflow point
• More than two paths between inflow and outflow
  points
• (Continued)

26
Water Distribution System Variables

• Piping arrangement (cont.)
• Valves
• Function in system
• Location in system
• Access
• Indicating
• Nonindicating
• Gate valves
• Butterfly valves
• (Continued)

27
Water Distribution System Variables

• Piping arrangement (cont.)
• Hydrants
• Dry-barrel and wet-barrel

28
Water Distribution System Variables

• Piping arrangement (cont.)
• Distribution and location
• Maintenance
• Color coding
• Less than 500 gpm Red
• 500?999 gpm Orange
• 1,000?1,499 gpm Green
• 1,500 gpm or more Light Blue

29
Private Water Supply Systems

• Purposes
• To provide water strictly for fire protection
  purposes
• To provide water for sanitary and fire protection
  purposes
• To provide water for fire protection and
  manufacturing processes
• Potential problems for fire fighting purposes
• (Continued)

30
Private Water Supply Systems (cont.)

• Water supply requirements for standpipe and hose
  systems
• NFPA 14, Standard for the Installation of
  Standpipe and Hose Systems
• Class I service
• Class II service
• Class III service
• (Continued)

31
Private Water Supply Systems (cont.)

• Water supply requirements for automatic sprinkler
  systems
• NFPA 13, Standard for the Installation of
  Sprinkler Systems
• Pipe schedule systems
• Hydraulically designed water-based extinguishing
  systems
• (Continued)

32
Private Water Supply Systems

• Water supply requirements for automatic sprinkler
  systems (cont.)
• Duration of water supplies
• See Table 3.5 in manual
• NFPA 231, Standard for General Storage