Fire Hydrants
In Accordance with IFC 2018,NFPA 24 & NFPA 1142
Mehboob Shaikh
(M. Tech | B. Eng. |AMIE | CFPS | CFI )
MECHSOFT ENGINEERING DESIGN AND CONSULTANCY
Contents
❑Types of Hydrants
❑Location of Fire Hydrants
❑Clear Space around the Hydrants
❑Distance Between the Fire Hydrants
❑Fire Hydrant Accessibility and Access
❑Fire Hydrant Flow Testing
❑Hydrant Loop Testing
MECHSOFT ENGINEERING DESIGN AND CONSULTANCY
Types of Fire Hydrants
Dry Hydrants
People
Generally
get
confused between this Two
Wet hydrants
Wet Barrel
According to NFPA 1142 Standard on Water Supplies for
Suburban and Rural Fire Fighting:
Key Sentence
“Dry hydrant is an arrangement of pipe permanently connected to a
water source other than a piped, pressurized water supply system that
provides a ready means of water supply for fire-fighting purposes and
that utilizes the drafting (suction) capability of a fire department pump”
MECHSOFT ENGINEERING DESIGN AND CONSULTANCY
Dry Barrel
DRY FIRE HYDRANTS
In dry hydrant water has to be drawn from the supply (lake,
pond, reservoir, tank) by a fire pumper through a pipe that is
typically located underground
MECHSOFT ENGINEERING DESIGN AND CONSULTANCY
WET FIRE HYDRANTS
MECHSOFT ENGINEERING DESIGN AND CONSULTANCY
Private vs Public Fire Hydrants
Everything after street valve will be maintained by
Property owner
Fire Hydrant
Public
Fire Line private
to building
Street Valve
8” Water mains
MECHSOFT ENGINEERING DESIGN AND CONSULTANCY
LOCATION
4.5 inch should face the
street
36” of clear space
must be maintained
around the hydrant
Min. 457 mm
Max. 914 mm
Bottom of the safety flange
should be at least 2.5
inches above the grade
where it is set
Approximately 6 feet
from traffic lanes
when no curb is
present
MECHSOFT ENGINEERING DESIGN AND CONSULTANCY
LOCATION
No parking within 15 feet of a fire
hydrant, which is marked by signage and
painting!!!
MECHSOFT ENGINEERING DESIGN AND CONSULTANCY
DISTANCE FROM THE BUILDING
Proposed
Building
Avoid placing it in Collapse Zone i.e.
perpendicular to the walls
Wall
Collapse
Fire hydrants must be placed Zone
(Collapse zone = 1.5 X height of building)
at least 40 feet from the
building they serve.
Wall
Collapse
Zone
At least 40 feet from the building they serve.
MECHSOFT ENGINEERING DESIGN AND CONSULTANCY
Public Street
DISTANCE FROM THE BUILDING
Proposed Building
Proposed walkway
25 feet
60 feet
Proposed walkway
Criss-cross fire hydrant
Proposed Building
90 feet
30 feet
Proposed Building
Too close to building
MECHSOFT ENGINEERING DESIGN AND CONSULTANCY
DISTANCE BETWEEN THE
HYDRANTS
Building Type
Maximum Distance between
Hydrants(feet)
Industrial buildings and warehouses
Schools, day care centers
250
What Exactly these distances means
..?
300
Offices, commercial establishments, church,
hospitals, nursing homes
350
Apartments, multifamily dwellings, town houses
350
Single-family dwellings
500
These measurements indicate what one fire hydrant can cover along the
fire access roadMECHSOFT
depending
on building
fire load and no. of fire
ENGINEERING
DESIGN type,
AND CONSULTANCY
streams required
FIRE HYDRANT COVERAGE
Within 150’
Proposed Building
Path 2: 350 feet max coverage
along required vehicle path
IIB, B, 2-story,
40 height, not
sprinklered
Fire trucks connect supply hoses to fire hydrants; so the
distance is based on how far the truck can travel from a fire
hydrant
MECHSOFT ENGINEERING DESIGN AND CONSULTANCY
Within 150’
Path 1: 350 feet max coverage
along required vehicle path
FIRE HYDRANT COVERAGE
Plot
Fire Truck Access way
Fire Truck Access way
Is it a right way to show
hydrant coverage ..? i.e. by
drawing a circle around the
hydrant.
MECHSOFT ENGINEERING DESIGN AND CONSULTANCY
FIRE HYDRANT COVERAGE
143’-9”
106’-3”
❑ 143’–9”+ 106’–3” = 250’
Path of truck travel with hose lay
We need to check coverage by laying
hose along the truck access path
considering all possible obstructions!!!
Plot
Coverage is not met if we
consider a circular coverage
around hydrant
MECHSOFT ENGINEERING DESIGN AND CONSULTANCY
Why Flow rate tests
❑Firefighters need to know how much water a hydrant will deliver. This
tells them how much fire can be extinguished using that particular
hydrant.
❑Knowing the capacity of a hydrant is just as important as knowing the
capacity of a pumper.
❑If the hydrant cannot supply enough water, the pump capacity does
not mean as much.
MECHSOFT ENGINEERING DESIGN AND CONSULTANCY
PERSONNEL AND EQUIPMENT FOR FLOW TESTS
EQUIPMENT
NAME
DESCRIPTION
QTY
Pitot Tube
For each flow hydrant, one Pitot tube with a pressure gauge
capable of reading from 0 to 60 psi (420 kPa).
1
One outletnozzle cap
One outlet-nozzle cap that will fit the outlet nozzle of the
residual hydrant. The outlet-nozzle cap is equipped with a
pressure gauge capable of reading from 0 up to 25 psi (175
kPa) greater than the pressure expected in the residual
hydrant.
2
A Ruler
A ruler to measure the inside diameter of the outlet nozzle of
each flow hydrant.
1
MECHSOFT ENGINEERING DESIGN AND CONSULTANCY
REPRESENTATION
PERSONNEL AND EQUIPMENT FOR FLOW TESTS
EQUIPMENT
NAME
DESCRIPTION
QTY
Hydrant
Wrench
One hydrant wrench to operate the residual hydrant and
one to operate each of the hydrants at which the flow will
be measured.
2
Discharge
diffuser
(Optional)
One discharge diffuser to absorb the energy from the
hydrant flow so that it is contained, where necessary, to
avoid property damage or to minimize the effect on traffic.
1
One Person
One person to read the gauge on the residual hydrant and
one person to read the gauge on the Pitot tube for each of
the flow hydrants.
1
MECHSOFT ENGINEERING DESIGN AND CONSULTANCY
REPRESENTATION
PERSONNEL AND EQUIPMENT FOR FLOW TESTS
EQUIPMENT
NAME
Hose
DESCRIPTION
QTY
50 ft section of 3” and/or 5” hose
2-4
Allen wrench
1
Clipboard
1
Paint supplies
Paint supplies (spray paint & masking tape)
-
Record keeping
material
Record keeping material
-
MECHSOFT ENGINEERING DESIGN AND CONSULTANCY
REPRESENTATION
Office Planning Prior to Field Testing
MECHSOFT ENGINEERING DESIGN AND CONSULTANCY
Set up
▪ Decide which hydrant will be your pressure hydrant and which will be your flow hydrant(s). The
pressure hydrant will be used to measure static pressure and residual pressure.
▪ Decide how many flow hydrants to use. As a rule of thumb, you should flow enough hydrants at
the same time such that the residual pressure drops at least 25% from the static pressure.
@ Test Hydrant(Static/Pressure/Residual Hydrant) :
▪ Attach gauge cap to test hydrant tighten all other caps
▪ Open test Hydrant, Vent Air from hydrant body through valve on the gauge assembly. Close it when air is vented.
▪ Open the hydrant slowly and fully;
▪ Read and record the pressure. This is the Static Pressure.
MECHSOFT ENGINEERING DESIGN AND CONSULTANCY
Set up
▪ @ Flow Hydrant:
• Measure and record the inside diameter (ID) of the outlet nozzle from which the
flow is measured. The inside diameter (ID) measurement is taken to the nearest
1/16 in. (0.159 cm).
• Insert a hand into the nozzle opening and feel the entrance shoulder to determine
the nozzle coefficient (0.9 for a smooth rounded shoulder, 0.8 for a square
shoulder, and 0.7 for a nozzle that protrudes into the barrel).
• Install and arrange any hoses or diffusers necessary to minimize effect on traffic
or landscaping.
MECHSOFT ENGINEERING DESIGN AND CONSULTANCY
FIELD PROCEDURE FOR FLOW TESTS
1. Make provisions for minimizing interruptions to traffic and for adequate
drainage of water.
2. At this point it would be helpful to have one or more assistants and a
reliable method of communication such as two-way radios to perform an
efficient test.
3. Open each flow hydrant slowly and fully. Open one hydrant at a time to
avoid a pressure surge
4. Wait for the pressure at the pressure hydrant to stabilize, read and
record this pressure. This is the Residual Pressure. Then signal the
persons stationed at the flow hydrants to take Pitot readings. The
readings for residual pressure and the Pitot readings should be taken at
the same time for an accurate flow.
MECHSOFT ENGINEERING DESIGN AND CONSULTANCY
FIELD PROCEDURE FOR FLOW TESTS
5. To take a Pitot reading, hold the Pitot gauge approximately ½ of the
diameter away from the nozzle in the center line of the nozzle. Read
and record this pressure. This is your Pitot or velocity pressure.
6. For an accurate reading, hold the Pitot tube in the center of the
nozzle, with the axis of the Pitot tube opening parallel to the direction
of flow. The Pitot tube should be held away from the end of the nozzle
at a distance of about half the nozzle diameter.
7. If sediment appears, continue to flow water until the main has been
flushed
8. Close each flow hydrant, one at a time, very slowly. Closing a
hydrant too fast will cause damage to the hydrant or to water mains.
MECHSOFT ENGINEERING DESIGN AND CONSULTANCY
FIELD PROCEDURE FOR FLOW TESTS
9. For reasonably accurate test results, the pressure drop between the static
and the residual pressures should be at least 10 psi (70 kPa).
10. If the distribution system is strong (as it should be near a supply main)
and the pressure drop is less than 10 psi (70 kPa), an additional flow hydrant
should be added to the test.
11. Enough hydrants should be opened to drop the Static pressure by at least
10 psi (70 kPa); however, if more accurate results are required, the pressure
drop should being the Residual pressure as close as possible to 20 psi (138
kPa). The flow available at 20 psi (138 kPa) can be determined by dropping
the Residual pressure to exactly 20 psi (138 kPa) or can be determined at any
Residual pressure by graphical analysis, or by formula calculations.
MECHSOFT ENGINEERING DESIGN AND CONSULTANCY
Equations
Qr=29.83 X CdX D^2 X Sqrt(Pp) ----------------(Eqn.1)
Qf=Qr X ((Ps-20)/(Ps-Pr))^0.54 ----------------(Eqn.2)
where:
▪ Qr is the residual flow at the Pitot pressure measured in gpm
▪ cd is the friction loss coefficient (usually 0.9 for a smooth 2½” opening)
▪ D is the diameter of the opening in inches
▪ Pp is the Pitot pressure in psi
▪ Qf is the FIRE FLOW in gpm at 20 psi
▪ Ps is the static pressure in psi
▪ Pr is the residual pressure in psi
MECHSOFT ENGINEERING DESIGN AND CONSULTANCY
Example
You Perform a Hydrant Test and gain the following results:
1.
2.
3.
4.
5.
Ps (Static pressure) = 140 psi
Pr (Residual pressure) = 125 psi
Pp (Pitot pressure) = 120 psi
cd = 0.9 because the inside of the nozzle was smooth.
D = 2.5 inches
MECHSOFT ENGINEERING DESIGN AND CONSULTANCY
Example
❑Calculate Qr (residual flow):
= 29.83 × 0.9 × (2.5)2 × square root of 125
= 29.83 × 0.9 × 6.25 × 11.18
= 1,876 gpm
❑Calculate Qf (fire flow):
= 1876 x ((140- 20)/(140- 125))^0.54
= 1876 x (8)^0.54 (raise 8 to the 0.54 power)
= 1,876 × 3.07375
= 5,766 gpm
MECHSOFT ENGINEERING DESIGN AND CONSULTANCY
Result
❑ That
system has the capacity to flow 5,766
gallons per minute at 20 psi residual pressure.
MECHSOFT ENGINEERING DESIGN AND CONSULTANCY
Why…? Marking of Hydrants
The marking of hydrants is important for two reasons.
1. It immediately tells fire crews the number and capacity of the fire
main system they are hooking into.
2. It shows that the owner is complying with this program.
Historically, fire crews have trusted public hydrants above private ones,
because the City hydrants are on a routine maintenance schedule, and,
generally, the likelihood of running into problems is lessened.
MECHSOFT ENGINEERING DESIGN AND CONSULTANCY
Marking of Hydrants
Classification of Hydrants. Hydrants should be classified in accordance
with their rated capacities [at 20 psi (1.4 bar)residual pressure or other
designated value] as follows:
1. Class AA — Rated capacity of 1500 gpm (5700L/min) or greater
2. Class A — Rated capacity of 1000–1499 gpm (3800– 5699L/min)
3. Class B — Rated capacity of 500–999 gpm (1900–3799L/min)
4. Class C — Rated capacity of less than 500 gpm (1900 L/min)
MECHSOFT ENGINEERING DESIGN AND CONSULTANCY
Marking of Hydrants
The tops and nozzle caps should be painted with the following capacity-indicating
color scheme to provide simplicity and consistency with colors used in signal work
for safety, danger, and intermediate condition:
1. Class AA — Light blue
2. Class A — Green
3. Class B — Orange
4. Class C — Red
❑NFPA 291 recommends that only the bonnet and caps be color coded. The rest of
the barrel should be a different color
❑For rapid identification at night, it is recommended that the capacity colors be of
a reflective-type paint.
MECHSOFT ENGINEERING DESIGN AND CONSULTANCY
Marking of Hydrants
MECHSOFT ENGINEERING DESIGN AND CONSULTANCY
Fire Main Loop Test with Fire
Hydrant
Why..?
❑To determine if the condition of the system is adequate to support a
Worst Case Credible Event(WCCE) need for firewater.
❑The condition of the piping, leaks, existence of closed valves or
sediment, operability of valves for firewater delivery systems
MECHSOFT ENGINEERING DESIGN AND CONSULTANCY
Fire Main Loop Test with Fire
Hydrant
When water flow encounters a loop or grid, two things occur
❑The flow splits into a determinable ratio
❑The pressure drop across each of the two legs will be the same
There are four methods to test a loop or grid system:
(1) Isolate the Legs
(2) Choose Two Hydrants on a Large Main
(3) Simultaneous Flow
(4) Single Hydrant Flow Test
MECHSOFT ENGINEERING DESIGN AND CONSULTANCY
Isolate the Legs : Test -1
Measure static pressure,
flow and residual pressure
SP1
RP1
Q1
Shut Valve -1
1
2
Source
MECHSOFT ENGINEERING DESIGN AND CONSULTANCY
Isolate the Legs : Test -2
Measure static pressure,
flow and residual pressure
1
Shut Valve -2
2
Source
MECHSOFT ENGINEERING DESIGN AND CONSULTANCY
SP2
RP2
Q2
Isolate the Legs : Test -3
Measure static pressure,
flow and residual pressure
Both valve opened
1
2
Source
MECHSOFT ENGINEERING DESIGN AND CONSULTANCY
SP3
RP3
Q3
Result
❑The static pressure should be identical in each of the three tests. A
drop in static pressure in test 1 or 2 is indicative of a restriction and a
leak.
❑In the event of a 100% restriction, no water will come out of the
hydrant
❑ In the event of a partial restriction, the residual pressure and/or the
flow is significantly diminished.
❑Further flow testing on different hydrants can usually narrow down
the location of the restriction
MECHSOFT ENGINEERING DESIGN AND CONSULTANCY
Choose Two Hydrants on a Large
Main
Dia. 4”
Dia. 4”
Dia. 6”
Dia. 6”
Both valve opened
1
2
Source
MECHSOFT ENGINEERING DESIGN AND CONSULTANCY
Thank You
MECHSOFT ENGINEERING DESIGN AND CONSULTANCY