Transcript 2010 DS Summit_JPD_11.4.10

Technical Review
Needed Fire Flow Analysis
Developer Services Summit
November 16, 2010
Engineering - Asset Planning
Joe Dugandzic, PE
Water System Design
Public water systems are generally designed and analyzed
hydraulically based on:
1. Peak hour domestic demands
2. Emergency condition purposes (typically fire fighting
and or power outage)
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Service Application Process: Who Does What?

Developer: Procures Design Professional to calculate
domestic and fire flow demands. Ensures that Fire Official
signs Needed Fire Flow (NFF) Worksheet.

Design Professional: Calculates expected domestic
demands and building’s NFF. Typically will prepare and sign
the NFF Worksheet on behalf of Developer.

Water Company: Evaluates system hydraulic and storage
capabilities based on Design Professionals demand
calculations. If necessary, identifies system improvements to
adequately deliver NFF.
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What Water Company Does Not Do

Prepares or reviews any Automatic Fire Suppression
System (AFSS) calculations

Requests Fire Official to sign NFF Worksheet

Requires existing customer base to finance system
improvements to be used for applicant’s benefit.
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Water Company “Behind the Scenes” Analyses

Performs regulated Supply Capacity review to
ensure system can add new customer demand.

Performs Hydraulic Modeling analyses using
applicant’s projected demands. Extended Period
Simulation identifies if new demands will create
any service pressure, excessive velocity, or
storage impact(s) to existing system.
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Water Supply Essentials for Fire Fighting

Rate of flow (gpm)

Residual pressure at that flow (psi)

Expected duration to contain a fire (hours)

Total quantity of supply needed (gallons)
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Example: NFF creates <20 psi residual pressure
Existing System + New Demands + 750 gpm NFF
48 psi
17 psi
750 gpm
1,000 feet, 6-inch Diameter, C=100
NG
Existing System + New Demands + 750 gpm NFF
48 psi
29 psi
750 gpm
500 feet, 6-inch Diameter, C=100
OK
500 feet, 8-inch Diameter, C=100
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Example: NFF could drain existing storage volume
Existing System with 500 gpm NFF
75,000 gallons
15,000 gallons
500 gpm x 120 mins = 60,000 gallons
OK
Existing System + New Demands & 750 gpm NFF
75,000 gallons
0 gallons
750 gpm x 120 mins = 90,000 gallons
NG
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American Water Planning Criteria
DISTRIBUTION PIPING, PUMP AND STORAGE EVALUATION
The ability of distribution system facilities to provide safe,
adequate and reliable service to customers is analyzed based
on:
• forecasted customer demands, and
• fire protection requirements
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Analysis of Facilities




Pipelines
Storage tanks
Booster stations
Emergency power
Under peak demand conditions, a number of minimum standards
should be met for each of these facilities.
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Pipelines

Distribution system mains are considered adequate if they
can meet customer demands at a minimum system
pressure of 20 psi.

Fire protection requirements should be met while
maintaining a minimum pressure of 20 psi in the
distribution system.

Note: State and local guidelines may require that higher
pressures be maintained.
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Distribution Storage

Storage facilities are considered adequate if the effective
volume of the facility, or groups of facilities acting
together, provide sufficient volume to meet equalization
needs and a fire protection reserve (if necessary) during
maximum day demand events.

State regulations are also considered as they relate to a
particular distribution system.
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Calculating Fire Flow Rates:
ISO Guide For Determination of Needed Fire Flow
Chapter 6 – Determining Recognition of Automatic Sprinkler
Systems. ISO uses Specific Commercial Property Evaluation
Schedule (SCOPES) to determine credit reduction of NFF for
automatic sprinkler system protection.
Must be installed and maintained in accordance to NFPA.
Potential NFF credit reduction is not given until an ISO field
inspection is conducted.
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Calculating Fire Flow Rates
What NFF should be requested on an application for
service to New Jersey American Water?
 ISO Non-Sprinklered
 NFPA Sprinklered
 Somewhere in between
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AWWA Manual of Water Supply Practices M31:
Preface

Addresses the planning, design, and maintenance of
distribution systems that supply water for fire protection
and suppression.

The emphasis is on public water systems and not on water
systems exclusively designed for fire protection.

The adequacy of a water distribution system for fire
protection depends on the fire flows required.
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AWWA Manual of Water Supply Practices M31

Water Supply Requirements for Sprinklered Properties
(p. 40)

A fire can occasionally overcome the capacity of a
sprinkler system.

Required fire flow for sprinklered properties consists of
the flow required for sprinklers, including a hosestream allowance or 500 gpm, whichever is greater.
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Calculating Fire Flow Rates

Based on the initial capital cost and operational expense
incurred by building owners for installing an AFSS,
American Water believes that some credit could be provided
at the time of a service request. The NFF Calculation
Worksheet was developed to ascertain NFFs at both ends of
the spectrum.

It also is used to provide the local fire official an opportunity
to acknowledge the building plans and provide experienced
input for additional allowances for “outside” hose streams
and adjacent structure exposure.
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Calculating Fire Flow Rates

NFF Calculation Worksheet

Developed by New Jersey American Water as a
screening tool

Although the higher NFF value is based on ISO’s “nonsprinklered” formulas, the worksheet is not endorsed or
sanctioned by the ISO

The NFPA 13 Automatic Sprinkler System value is not
checked or approved by the water company or the local
Fire Official

Should be used as a guide in determining the “water
system” NFF
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Calculating Fire Flow Rates: Commercial and
Multi-Family Buildings

New Jersey American Water is not responsible for operating
and maintaining an AFSS. With an agreement from a
building or property owner to be diligent in the AFSS
maintenance, the company will consider recognizing an
AFSS reduction for commercial or multi-family buildings or
structures to a minimum of 1,000 gpm, should the NFPA 13
automatic sprinkler system flow, and requested fire official
hose stream allowances be equal to or lower than 1,000
gpm.
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Calculating Fire Flow Rates: Residential One- and
Small Two-Family Dwellings

If a new one- and small two-family dwelling is proposed with
individual AFSSs, New Jersey American Water will
recognize a NFF credit. In lieu of using ISO’s “nonsprinklered” NFF determinations (Table 7, Guide For
Determination of NFF), the company will reduce the small
residential dwelling NFF to a minimum of 500 gpm, provided
the NFPA 13D automatic sprinkler system flow and
requested fire official hose stream allowances are equal to
or lower than 500 gpm.

If the proposed development does not include AFSS, ISO’s
Table 7 NFF will then govern.
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Thank You.
Questions?
Lets now review the NFF Calculation Worksheet.
Emphasize Residential vs. Commercial/Industrial
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