what are the two basic types of water systems in North America?
-public water supply distribution systems are generally a function of the local government. the local water dpt is usually a separate city utility and is governed by an elected board.
-a private water supply system may provide water under contract to a mu
what are the basic components of all water supply systems?
-water supply sources: lakes, reservoirs, ponds, rivers, streams, wells or springs
-processing or treatment facilities: purification or desalination plants
-means of removing the water: water pumps
-water distribution and storage systems: storage tanks, c
gravity systems
a gravity water system delivers water from the source or the treatment plant to the distribution system without pumping equipment. the difference in the height of the water source and the point of use creates elevation pressure (also known as elevation he
direct pumping systems
water supply system supplied directly by a system of pumps rather than elevated storage tanks.
the main disadvantage of this system is their total dependence on pumps (subject to mechanical failure) and on electricity (subject to power outages) to run the
combination system
water supply system that is a combination of both gravity and direct pumping systems. it is the most common type of municipal water system.
water main
a principal pipe in a system of pipes for conveying water, especially one installed underground.
underground water mains are generally made of cast iron, ductile iron, asbestos cement, steel, polyvinyl chloride (PVC) plastic, or concrete.
grid or gridiron
the interlocking network of water mains that compose a water distribution system. consists of three main types of water mains: primary feeders, secondary feeders and distributors
primary feeders
large pipes, also known as arterial mains, with relatively widespread spacing. these mains convey large quantities of water to various points in the distribution system and supply smaller secondary feeder mains.
can be very large. ranging from 16in to 72i
secondary feeders
intermediate pipes that interconnect with the primary feeder lines to create a grid. they are 12 to 14 inches in diameter. control valves can be used to isolate each secondary feeder.
distributors
small water mains, 6 to 8 inches in diameter, that serve individual fire hydrants and commercial and residential consumers. distributors may form an intermediate grid between the secondary feeders or may be dead-end lines with the hydrant or supplied prop
water supply considerations
to ensure a sufficient water supply, two or more primary feeders should run from the source of supply to the high-risk and industrial districts of the community along separate routes .
similarly, the secondary feeders should provide water from the primary
storage tanks
elevated gravity storage tanks are usually constructed of steel or concrete. gravity tank capacities range from 5,000 gallons to over a million gallons
isolation and control valves
water supply systems contain valves to interrupt water flow to: individual hydrants or properties, distribution lines, secondary feeders, primary feeders, and entire water systems
most valves are constructed of brass, steel or cast iron
two types of valve
isolation valves
-also known as stop or shutoff valves and are either gate valves or butterfly valves. are used to isolate sections for maintenance and repair, to replace hydrants, or to make new connections to the system. the location of isolation valves is intended to d
gate valve (review)
control valve with a solid plate operated by a handle and screw mechanism; rotating the handle moves the plate into or out of the waterway
butterfly valve (review)
control valve that uses a a flat circular plate in a pipe that rotates 90 degrees across the cross section of the pipe to control the flow of water
common indicating valves
-post indicator valve: a type of valve used to control underground water mains that provides a visual means for indicating "open" or "shut" position; found on the supply main of installed fire protection systems
-outside stem and yolk valve: a type of con
control valves
also located between public water supply distribution systems and private water supply distribution systems.
typical types of control valves include: pressure-reducing, pressure-sustaining, pressure-relief valves, flow-control valves, throttling valves, f
fire hydrant locations
located along all portions of the water supply system and are generally connected at specified intervals by 6in connecting pipes. water dpt personnel usually determine the location, spacing and distribution of fire hydrants.
in general, fire hydrants shou
dead-end hydrant
receives water from only one direction and consequently has a limited water supply
circulating hydrants
receive water from more than one direction and are said to have circulating feed or a looped system.
circulating feed - fire hydrant that receives water from two or more directions
loop system - water main arranged in a complete circuit so that water will
hydrant failure
failures or reduction in water supply can result from:
-damaged hydrant valves and connections
-broken water mains
-greater demand than the system can provide
-hydrants located on dead-end water mains
-closed isolation valves
-restricted mains caused by s
fire hydrants
all fire hydrant bonnets, barrels, and foot pieces are made of cast iron. the internal working parts are usually made of bronze, but valve facings may be made of rubber, leather or composite materials
hydrant discharge outlets are considered standard if t
NFPA 1963
Standard for fire hose connections - sets regulations for the number of threads per inch and the outside diameter of the male thread
dry-barrel hydrant
fire hydrant that has its operating valve located at the base or foot of the hydrant rather than in the barrel of the hydrant. when operating properly, there is no water in the barrel of the hydrant when it is not in use. these barrels are used in areas w
wet barrel hydrant
fire hydrant that has water all the way up the discharge outlets; may have separate valves for each discharge or one valve for all the discharges. this type of hydrant is only used in areas where there is no danger of freezing weather conditions
NFPA 291
recommended practice for fire flow testing and marking of hydrants (p.796)
Red class C 500gpm or less
Orange class B 500-999gpm
Green class A 1000-1499gpm
Blue class AA 1500gpm or more
hydrant flow rates (SLIP)
acronym to remember the factors that affect hydrant flow rate:
S - size of the main (diameter)
L - length of the main (distance b/t hydrants)
I - internal condition of the main (roughness caused by age or sediment)
P - pressure within the main (actual flo
wet-barrel hydrant operation
1. ensure the valve is shut by placing the hydrant wrench on the operating stem and turning clockwise
2. tighten the discharge caps that will not be used and then remove the cap from the discharge outlet onto which you are going to attach the hose
3. chec
dry-barrel hydrant
to prevent freezing, the dry barrel main valve is located underground below the frost line. when the stem nut is turned counter-clockwise, the main valve moves downward allowing water to flow into the hydrant. as the main valve moves downward, a drain val
draining of dry-barrel hydrant
1. close the main valve by turning the stem nut clockwise until resistance is felt; then turn it a quarter-turn counterclockwise
2. cap all discharges except one
3. place the palm of one hand over the open discharge
if the hydrant is draining a small vacu
fire hydrant inspection
look for the following:
-obstructions that might interfere with pumper-to-hydrant connections or with opening the hydrant valve
-outlets that face the wrong direction for pumper to hydrant connections
-insufficient clearance between outlets and the ground
drafting operations
process of acquiring water from a static source or transferring it into a pump that is above the source's level; atmospheric pressure on the water surface forces the water into the pump where the partial vacuum was created.
when drafting from any natural
NFPA 1142
standard on water supplies for suburban and rural fire fighting
water shuttle operation
method of water supply by which mobile water supply apparatus continuously transport water between a fill site and a dump site located near the emergency scene
-recommended for distances greater than 1/2 mile from the nearest fire hydrant or water source
portable tank
storage tank used during a relay or shuttle operation to hold water from water tanks or hydrants. this water can then be used to supply the attack apparatus.
have capacities beginning at 1,000 gallons
when two portable tanks are used, they can be connecte
NFPA 1901
standard for automotive fire apparatus - requires that mobile water supply apparatus on level ground can be capable of dumping or filling rates of at least 1000gpm
relay pumping
use of two or more pumpers to move water over a long distance by operating them in series. water discharged from one pumper flows through hoses to the inlet of the next pumper and is then pumped to the next pumper in line
two important factors must be con
quint
a quintuple combination pumper or quint is a fire service apparatus that serves the dual purpose of an engine and a ladder truck. the name refers to the five functions that a quint provides: pump, water tank, fire hose, aerial device, and ground ladders.