Water Supples

Question 1

Three types of water supplies

Answer 1

• Three types of water supplies
• Public
• Private
• Non-potable – raw water
• must meet or exceed the minimum duration and demand for
water supplies; as detailed in NFPA and by the AHJ.
• water supply requirement is determined:
• by evaluating the number of sprinklers expected to operate from
any one fire
• Determine the flow and pressure required
• Determine the duration
• plus the quantities needed for simultaneous hose stream
allowances (quantity of water required when fighting the fire
with fire hoses).

Question 2

Determining Requirements

Answer 2

Determining Requirements
• The authorities will outline their requirements. For example,
they may state that in an area of 3000 square feet to be
protected, they will require a coverage of water with a density
of 0.17 gpm/ft² = ? + hose stream allowance
• Pressure must be evaluated with friction loss and elevation
• Compare what is required to what is available
• Generally requires a flow test, or it may be provided by the
supplier

Question 3

Public water supply

Answer 3

Public Water Supply
• City Supply – water is supplied from city, municipality, …., they:
• supply and make the 6-inch connection to the street line
• place a valve connection on it
• Provide a valve box and cover where the connection is attached to
their main
• Typically at the property line

Question 4

Underground piping codes

Answer 4

private fire service mains should not run more than 10ft under the building.

no joints under foundation - unless sleeved

installed minimum 12 inch below foundation

joints have to be restrained

Question 5

Private water supply

Answer 5

Private Water Supply NFPA 24
• Private water supply systems are not usually part of the public
water supply
• Often the pipe is too small, so it is difficult for these systems to
provide the water demands of the proposed project.
• When this is the case
• the water supply will either be supplied solely from a stored water
supply
• or a stored water supply can be used to increase the water supplied to
the property.
• The stored water can be:
• Pressure tanks
• Storage tanks
• Reservoirs
• Lakes, penstocks, flumes, rivers

Question 6

Private fire service mains

Answer 6

if suppling hydrants - shall not be less than 6”

If pipe scheduled - service main should be at least the size of the riser

Question 7

post indicator valve

Answer 7

not less than 40 feet from the building

Question 8

Pressure tanks

Answer 8

Pressure Tanks
• #1 limited water supply
• Steel water tanks under pressure have been used for many years
in the fire protection industry.
• They are best installed at the top of a building, for gravity, but
also may be stored at lower levels
• 1/3 air + 2/3 water
• can also be used in conjunction with other water supplies
• Supplies water under pressure immediately. Since most fires can
be controlled by automatic sprinklers if water is supplied
immediately, these tanks are extremely viable

Question 9

Pressure tanks

Answer 9

most common sizes used for fire protection are from 6000 – 9000
gals
• For light hazard occupancies pressure tanks should have an
available water capacity of not less than 2,000 gallons.
• In ordinary hazard occupancies, Group 1 or 2, the water capacity
available should not be less than 3,000 galIons.
• usually operate at 125 PSI working pressure

Question 10

Air supply

Answer 10

electrically driven air compressor
7500 >= tanks 16CFM at >= 5psi above operating pressure
For larger tanks >= 20CFM
Piping >= 1”
globe valve + check valve
Relief valve (3/4”) keep pressure from rising >10% above

Question 11

Discharge pipe

Answer 11

taken from the bottom of the tank and should protrude 2” above the inside bottom of the tank for sediment
<5000 gals = 4”
5000-9000 = 6”
control valve + check valve + swing joint to provide for expansion
The drain connection be 1 1/2” diameter and be controlled with a globe valve

Question 12

Accessories

Answer 12

4 1/2” air pressure gauge range = 2x working pressure + 3way
3/4” water level gauge
tank nameplate with an arrow to indicate proper water level
Nameplate should indicate:
-air operating pressure
-name and address of the manufacturer
-year the tank was made
-capacity in gallons and the maximum permitted water pressure

Question 13

Maintenance

Answer 13

painted inside and outside with two coats of metal protective paint
the air pressure and water level must be checked at least once a week
the correct pressure and water level properly maintained
generally kept 2/3 full of water and 1/3 full of air

Question 14

Break tank

Answer 14

A Break Tank is a non-pressurized, closed water tank,
• with an air gap to ensure zero backflow between the city water
supply and the fire pump suction. …
• To eliminate pressure fluctuations in the city water supply and
provide a steady suction pressure to the fire pump.
• In easy words, a suction tank is a reservoir to supply water to any
system.
It is a closed container that maintains partial or complete vacuum
inside it to be able to draw things into the inlet port.

Question 15

sizing of tank

Answer 15

stored supply plus reliable automatic refill shall meet the system demand for the design duration

Question 16

Gravity tank

Answer 16

Gravity tanks can be used as the sole water supply but are
usually used in conjunction with another water source.
• water is supplied by a water tower or tank that is normally
elevated.
• The AHJ shall be consulted before the tank is designed and
installed
• Some years ago, the standard method of supplying water to fire
protection systems in the upper floors of tall buildings was to
install a wooden tank at the top of the building and to connect
the discharge pipe from it to the sprinkler system. This provided
a positive secondary water supply.

Question 17

Elevated steel storage tanks

Answer 17

often used to protect large properties where an ample supply of
water is required for fire protection.
• used where no public water mains are available for fire
protection, or the public supply isn’t adequate
• The type to be used, its capacity, location, foundations, etc, are
usually specified by the authority having jurisdiction.
• The sprinkler installer must be familiar with his area of the work,
which generally includes all piping: supply, discharge, overflow,
drains, filling, heating, testing and alarms.

Question 18

Double ellipsoidal ( type of elevated steel storage tank)

Answer 18

Double ellipsoidal – named due to the
shape of its bottom and roof
• The capacity of the tank is usually based on the number of U.S.
gallons available above the outlet opening, located at the
bottom of the tank
• The most common sizes of tanks designed for use with fire
protection systems are 50,000, 60,000, 75,000 and 100,000 US
gallons net capacity
• These tanks are similar, their locations and uses often differ
• Supply for domestic water
• Supply for fire protection
• Provide pressure
• Red Deer tank = 2,000,000 gals when it was built it was the
largest in NA. Used for domestic supply and pressure

Question 19

Tanks with large riser

Answer 19

• drop riser is full of water when the tank is in full service.
• It does not have an enclosure around the riser
• A discharge line is connected at the bottom inside the riser
• Use 6” pipe for tanks up to 25,000 US gallon capacity, and 8” pipe
for tanks of 30,000 to 100,000 U.S. gallon capacity
• The best method of filling the tank is to install a 2” by-pass line
around the check valve located at the base of the riser. This line
should contain an OS & Y valve.
• Shall fill in 8 hours
• considerable pressure is required to fill the tank (at least 50 PSI).
• Generally, requires a pump to fill the tank
• This pump must be capable of filling the tank in eight hours.
• The fill pipe should be >2” diameter and may be connected to the
tank discharge line on the tank side of the check valve.

Question 20

Double ellipsoidal tank features

Answer 20

The double ellipsoidal tank has the following features:
• The shape of the tank and the use of a large riser which is full of
water from the base of the tank to the ground.
• A large support pedestal is used but is not full of water.
• The interior of the pedestal is accessible and contains the 8”
discharge piping, usually Insulated.
• This type of tank enables a person to climb from the ground to
the platform at the bottom of the tank, pass up through an
access tube located in the tank, and then climb to the top of the
tank.
• Elevated tank detail

Question 21

Water Storage Tanks (for Fire Pump Suction Supply)

Answer 21

Steel storage tanks or reservoirs which rest upon foundations at
ground level can be furnished in various ways for use as a fire
pump suction supply.
• Standard accessories usually include a manhole in the shell near
the bottom, a manhole in the roof, a vented roof fitting, inside
and outside ladders, a painter’s trolley rail and connections for a
suction pipe, overflow pipes
• Approved sizes for these tanks are 100 000,150 000, 200 000, 250
000, 300 000, 400 000, 500 000, 750 000 and 1 000 000 US gallon
capacity
• When used for fire protection and sprinkler systems, must
conform to NFPA 22

Question 22

Water Storage Tanks (for Fire Pump Suction Supply)

Answer 22

• Heat must be provided, circulating water is not sufficient
• The tank is filled by installing a 2” by-pass with a control valve
around the large check valve on the fire pump discharge line.
• NFPA 22 Annex B, typical installations

Question 23

• Non-Potable/Raw Water Supply

Answer 23

Non-potable water sources include penstocks (pipes),
flumes(chanels), rivers, lakes and reservoirs.
• When using a raw water source, health issues can be a concern
and the AHJ shall be consulted.
• Reservoirs may be made of concrete and erected inside or
outside the building
• They are generally used for fire pump suction water supply.
• One of the best methods of providing a reserve for fire pump
water supply, if natural methods are not available, is to use
“embankment-supported” rubberized tanks
• Because of latent heat in the stored water and earthen
embankments, the tanks rarely require heating to prevent
freezing. If heating is required, water may be pumped through
heat exchangers and through circulating piping

Question 24

Fire Pumps

Answer 24

A centrifugal fire pump is the most common type of
fire pump used in the fire protection industry
• A fire pump sized in accordance with NFPA 20, that is
supplied under positive head can be used in
conjunction with a non-potable water supply to form
part of an acceptable water supply source.
• a fire pump boosts the water pressure.
• Fire pumps don‘t create water but simply move the
water through the pipe more quickly because of the
pressure increase they develop.

Question 25

Penstock and Flumes

Answer 25

• A flume is a channel where water flows
• A penstock is an enclosed structure or pipe
Rivers or lakes may be used if they are
acceptable to authorities
there has to be a record of non drought
conditions for10 years

Question 26

Raw Water - penstock and flumes

Answer 26

NFPA states that water supply connections from
penstocks, flumes, rivers and lakes shall be arranged to
avoid mud and sediment.
• These shall be provided with approved double removable
screens or approved strainers in an approved manner
• Pendants on return bends
• The sprinkler installer must be familiar with his area of
the work, which generally includes all piping: supply,
discharge, overflow, drains, filling, heating, testing and
alarms.

Question 27

Corrosive Water Supplies

Answer 27

Corrosive water can create fracturing within the pipe or buildup
of deposits leading to:
• Reduced flow progressing to complete obstructions
• Compromised sprinkler system
• Pinhole Leaks

Question 28

Inside pipe corrosion can be caused by:

Answer 28

Electrolysis – breakdown via electricity
• oxygen concentration cells – metals combined with oxygen = rust
• galvanic corrosion – two dissimilar metals and an electrolyte
(water) the more reactive (anode) breaks down quicker

Question 29

Corrosive Water Supplies

Answer 29

Many factors can help influence the corrosion:
• pH – measure of the acid or base of the water
• Alkaline vs basic
• oxidizing agents – reacting with oxygen
• carbon dioxide – can create carbonic acid which corrodes steel
• dissolved solids – allows for better conductivity -> galvanic
corrosion
• Temperature – faster electrochemical reactions
• velocity of flow - scouring
• Bacteria – bacteria colonies -> deposits
• metal characteristics – higher electrode metals corrode slower
• stray currents.

Question 30

Water + best pH level

Answer 30

If the pH level is too high in water, it can cause deposit
or scaling on the pipe walls.
• If the pH level is too low, it can degrade the pipe and
create pinhole leaks
• A neutral pH level is 7
• Water mixes with almost anything
• Raw water sources are particularly susceptible
• May require water treatment
• follow routine testing, and using preventative measures
as recommended in the NFPA 25 Standard for the
Inspection, Testing, and Maintenance

Question 31

Assessment of internal condition

Answer 31

minimum every 5 years but risk analysis can establish a different frequency  
minimum four-point inspection:
1.system valve
2. riser
3. cross main
4. branch line

Question 32

The rate of corrosion on a piping system is accelerated by

these factors:

Answer 32

The pH of the water.
• The amount of oxygen in the water.
• The chemical makeup of the water.
• The amount of galvanic corrosion from the use of dissimilar
metals contained in or in contact with the piping system.
• The temperature of the water.
• The velocity/pressure of the water in the pipe.

Question 33

The nine main forms of corrosion include:

Answer 33

1. Uniform corrosion or general corrosion:
   • A regular loss of a small quantity of metal over the entire area
2. Pitting:
   • Localized form of corrosion that results in holes or cavities in the
   metal, normally forms in the direction of gravity
3. Galvanic corrosion:
   • An electric potential exists between dissimilar metals in a conductive
   (corrosive) solution
   • cathode + and anode –
4. Crevice corrosion:
   • occurs within crevices and other shielded areas on metal surfaces
   exposed to a stagnant corrosive solution.
5. Selective leaching:
   • The selective removal of one element from an alloy by corrosion eg.,
   dezincification
6. Erosion corrosion:
   • Corrosion resulting from the cumulative damage of electrochemical
   reactions and mechanical effects
   • grooves, gullies, waves, rounded holes, or valleys in a metal surface.
7. Environmental cracking
   • caused by mechanical stresses, embrittlement, or fatigue.
8. Integranular corrosion –
   • within the makeup metal there are grains, this attacks at the
   boundaries of the grains
9. Microbiologically influenced corrosion (MIC):
   • Corrosion initiated or accelerated by the presence and activities of
   micro-organisms, including bacteria and fungi.

Question 34

Monitoring

Answer 34

corrosive monitoring must be part of the system
maintenance bid package to prevent large losses due to
unexpected pipe failures and sprinkler head false
activation.
• Monitor the system rather than wait for the leaks
• Sonic Inspection
• Wall thickness measurements.
• Digital video show video https://youtu.be/BLQekdZg3Qs
• Water samples
• 3D laser scanner technology

Question 35

Ownership

Answer 35

The water purveyor ensures the water quality to the
property
• Pipes
• Hydrants
• Valves
• Water treatment
• monitoring

• The owner is responsible for the water within the
property

Question 36

Procedures

Answer 36

• Investigate dry systems first
• System can be considered ok if:
• < ½ cup of scale, scale isn’t large enough to plug a sprinkler
• Go to most likely locations, known obstructions, warm areas, low
points…
• Flow 2 ½” lines from cross mains, 1 ½” through branch lines
• Use burlap bags to collect material
• Flow until water clears
• If a fire pump is on the system, let it flow

Question 37

Identify and treatment

Answer 37

Coating the inside of the pipes.
• Galvanized pipe on dry systems????
• Use of CPVC.
• Flushing a system to help slow down corrosion
• Biocide – fights against MIC
• Chlorine – kills bacteria
• Dielectric union – electrolysis prevention
• Cathode protection – neutralizes electrical current
• Rectifier – introduces DC current
• Nitrogen – eliminates oxygen and therefore the oxidizing agent
• Air dryers – removes moisture from the piping
• Monitoring probes – monitors the level of corrosion
• Langelier Saturation Index