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NFPA20

Standard for the Installation of Stationary Pumps for Fire Protection


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Codes and Standards

National Fire Protection Association -NFPA Establishes the norms that governs all fire

installation Continuously revises the codes (Last issue

2003)


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Codes and Standards

NFPA Philosophy A fire pump system should operate irrespective

of any damage it may cause to itself

No element of the system under emergencyconditions should:

Prevent a fire pump from turning onCause a fire pump to turn off

Changes to the code must be substantiated bydata or experience (actual scenarios)


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Codes and Standards

NFPA20 Structure: Definitions (3 pages) Centrifugal Fire Pumps (5 pages)

Positive Displacement Pumps (2 pages) Electric Motors (1 page) Diesel Engines (4 pages)

Controllers (12 pages) Pump Installation and RelatedComponents (10 pages)

Acceptance Tests and Maintenance (2pages)


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Water Supply Where fire pumps are installed on a city main, a fire

flow test should be performed to determineminimum and maximum supply pressures as wellas suitability of supply for the fire protection system

Where adequate city supply water is unavailable, asuction tank or pit should be installed

Tank sizing must consider 150% of the fire pumprated flow

Total water requirements are defined in NFPA13(Sprinkler Systems), NFPA14 (Standpipe Systems),NFPA15 (Spray or Mist Systems), Mains)


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Pump RequirementsCentrifugal fire pumps shall be listed for

fire protection service.

Pumps shall furnish not less than 150% of rated capacity at not less than 65% of total rated head. The shutoff head shallnot exceed 140% of rated head for any

type pump.


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Pump Requirements

100% 150%

140%100%65%

%Rated Head

%Rated Flow

Max Shutoff Head


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Pump SizingA stationary pump for fire protection should be

selected in the range of operation from 90percent to 150 percent of its rated capacity. Theperformance of the pump when applied atcapacities over 140 percent of rated capacity can

be adversely affected by the suction conditions. Application of the pump at capacities less than90 percent of the rated capacity is notrecommended. The selection and application of the fire pump should not be confused with pumpoperating conditions. With proper suctionconditions, the pump can operate at any point onits characteristic curve from shutoff to 150percent of its rated capacity.


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Misinterpreted CodeRequirement

Sizing the fire pump - a listed pump shouldbe applied for flows from 90% to 150% of its rated point

Most fire pumps are sized to exceed theduty requirement of the fire protectionsystem

The rated flow is a convention used toregulate the listing of pumps


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Pump Requirements

FM & UL require that fire pumps havepacking sealsULC allows mechanical sealsPacking requires periodic adjustment andreplacement as it hardens over time

The packing gland should be tighteneduntil the seal leaks 30 drips per minuteIf the gland is tightened to much, the sealreceives no lubrication and will burn


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Allowable PumpTypes

Horizontal Split Case Vertical In-Line

End Suction Vertical Turbine


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Horizontal Split Case FirePumps


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HSC Fire Pumps

BENFITS Available in a wideflow and head range

Serviceable without

disturbing piping or driver Available in electric

or diesel drive

DRAWBACKS Large floor spacerequirement

Restricts mechanical

room layout due todirection of rotation More costly More difficult to

service


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VIL Fire PumpsBENEFITS Compact Serviceable Reliable

Cost Effective

DRAWBACKS Only available up to

1500GPM Electric Drive Only Requires suction

strainer


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End Suction Fire Pumps


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End Suction Fire Pumps

BENFITS Moderate floor spacerequirement

Flexibility in

mechanical roomlayout Available in electric

or diesel drive

Serviceable

DRAWBACKS Only available up to1500gpm

Single suction

design limitshydraulic efficiency


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Vertical Turbine FirePumps

Used where aflooded suction

cannot bemaintainedUnderground water sources or belowground tanks withabove ground pumproom


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Vertical Turbine Fire

PumpsBENFITS Will operate under

suction lift Available in electric

or diesel drive Available over wide

flow and head range

DRAWBACKS More costly

More difficult toservice and install


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Typical ApplicationWet Pit - Electric

Motor Driver


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Typical ApplicationWet Pit - Diesel Engine Driver


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Suction &DischargeGauges Air Release

Valve

Pressure Relief Valve three pressureranges adjustable on site

NFPA RequiredPump Accessories


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Suction gauge must be of the compound type (capableof reading negative pressureor vacuum)Discharge gauge must readtwo times the workingpressure of the pump andnot less than 200psi

NFPA RequiredPump Accessories


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1/2 Air Release Valve isrequiredException: top centre-line

discharge end suction andvertical fire pumps

Air Release Valve


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3/4 up to 2500usgpm1 over 3000usgpmShould be set between themaximum suction pressure andminimum suction pressure plusthe closed valve pressure of thepump

Piped before the fire pumpdischarge check valve

Casing Relief Valve


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Suction OS&Y Gate Valve Discharge Butterfly Valve Both must be supervised Discharge Butterfly Valve

Installed after Test Teeand pressure sensing line

Isolation Valves


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Hose Valve Systems

Provides testing means Sized by pump rated

capacity

There are hundreds of different thread typesdepending on jurisdiction- type should bespecified on projects


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Main Relief Valves

and Waste Cones Sized by pump ratedcapacity

Spring or pilot operated Waste cone provides

visibility of flow throughthe valve

When it is used:1) Diesel driven systems

2) Electric systems ???


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Main Relief Valve -Diesel Pumps

1000

30

165

130

psi

GPM

Shutoff Head

@ Rated Speed

20

1500

Shutoff Head@ 10% Overspeed179


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Main Relief Valve -Electric Pumps

1000

60

180

130

psi

GPM

Max Shutoff Head

20

1500

Rated Head


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Misinterpreted CodeRequirement

Devices in the discharge piping - mainrelief or pressure reducing valves shouldonly be installed where absolutely

necessary Valves introduce a failure mode and

should only be used when required


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Piping, Relief Valves, Metering Devices, andHose Valves should be sized according to

Table 2-20 on Page 20-13.

NFPA Fitting Sizing


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NFPA RequiredPump AccessoriesFire Pump Rating

GPM (L/s)Suction

Size (in.)DischargeSize (in.)

Relief ValveSize (in.)

Relief ValveDischarge

(in.)

Flow Meter Size (in.)

Number &Size of Hose

Valves

Hose ValveManifoldSize (in.)

25 (95) 1 1 1 1 1 - 1 150 (189) 1 1 1 1 2 1 - 1 1100 (379) 2 2 1 2 2 1 - 2 2150 (568) 2 2 2 2 3 1 - 2 2200 (757) 3 3 2 2 3 1 - 2 2

250 (946) 3 3 2 2 3 1 - 2 3300 (1136) 4 4 2 3 3 2 - 2 3400 (1514) 4 4 3 5 4 2 - 2 4450 (1703) 5 5 3 5 4 2 - 2 4500 (1892) 5 5 3 5 5 2 - 2 4

750 (2839) 6 6 4 6 5 3 - 2 61000 (3785) 8 6 4 8 6 4 - 2 61250 (4731) 8 8 6 8 6 6 - 2 81500 (5677) 8 8 6 8 8 6 - 2 82000 (7570) 10 10 6 10 8 6 - 2 8

2500 (9462) 10 10 6 10 8 8 - 2 103000 (11,355) 12 12 8 12 8 12 - 2 10


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Jockey PumpsJockey (pressure maintenance) pumps and

jockey controllers need not be listed for fireprotection service.

The primary or standby fire pump shall not beused as a pressure maintenance pump.

A jockey pump should be sized such that itCANNOT meet the flow demand of a singlesprinkler fixture.


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Fire Pump Operation Fire pumps are designed to start on a

pressure switch setting Some fire pumps can be started automatically

based on a deluge valve opening, or a remotesignal

The pressure sensing line is the lifeline for thefire protection system


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Fire Pump Operation Pressure switches should be rated for maximum

pressure conditions Sensing lines must be 1/2 non -ferrous (copper)

with two check valves with a 3/32 hole drilled in the

flapper Check valves are for damping of pressure when thepump starts to protect the pressure switch

Check valves are installed 5 feet apart and mustopen on a pressure drop in the sensing line

Check valves close when the pump starts Jockey pump and fire pump sensing lines must be

separate


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System gradually loosespressure

50

9095100

110

Jockey startFire Pump start

Stop PointPump shutoff

psi

Time period

boost

Fire Pump Operation


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Critical New Code Requirements(2003)

Extensive changes to NFPA20 includingchapter numbers

Fire pump sizing will move from the

Appendix to the main text of the code Greater clarity on devices in the discharge

piping

Provisions for the acceptance of electronicspeed governors on diesel engines Reference to NEMA ICS 14-2001 as

Appendix B (Application Guide for ElectricFire Pump Controllers)


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Critical New Code Requirements(2003)

Diesel tank supervision and markings Alternate valve arrangement for diesel

cooling lines

Provision for reading amperage andvoltage on limited service controllers

Variable speed drivers as pressure limiting

devices Copper lines and fittings not allowed for

diesel piping


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Typical System Performance - 500gpm, 160psiincluding 85psi Suction Pressure

100

110

120

130

140

150

160

170

180

190

200

210

220

0 50 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800

Flow - GPM

H e a

d -

P S I

2700

2800

2900

3000

3100

3200

3300

3400

3500

3600

R P M

PLT OFF 85psi SuctPLT ON 85psi SuctPLT ON 85psi RPMPLT OFF 85psi RPM

System PressureLimit

Pressure LimitingControl Range

RPM

System Pressure

RPM


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FIRE PUMP CONTROLLERS

Diesel or ElectricFull Service or Limited Service

HP of the motor Voltage of the installationWithstand rating

Starting method


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Across the Line Limited Service - Under 30hp Full Service

Reduced Voltage Auto Transformer Wye Delta - Special Motor

Required Part Winding - Special Motor

Required

Primary Resistor

CONTROLLER STARTING METHOD


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CONTROLLER STARTING METHOD600

% of FullLoad

Current

Full speed

390

252200

FULL VOLTAGE

PRIM.RESISTOR

PART WINDING

AUTO-TRANSFORMER

WYE DELTA

FULL LOADCURRENT

420

100


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AUTOMATIC TRANSFERSWITCHES

What is it? An additional controller used

in case of a power failure

Why use it? To transfer the power toanother source (generator or diesel)

When to use it? If Authorities Require One If Power Source not Reliable


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Serve Three Basic Functions : Start the Diesel Engine in an emergency Monitor the Operation and Condition of the

Diesel Engine Keep the batteries charged

DIESEL CONTROLLERS


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Diesel Can be Stopped by TwoMethods : Manually by Pushing the Stop Button

Automatically after 30 minutes duringweekly test

Overspeed shutdown:

A diesel fire pump will shut down in anemergency condition if the diesel operatesmore than 20% faster than the ratedspeed

DIESEL CONTROLLERS


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Diesel Controller Alarms Battery and Charger Failures Diesel operating condition (High Coolant

Temperature, Low Oil Pressure, Overspeed,Failure to Start) Contacts for remote indication of alarm

conditions Optional Pump Room Alarms (Low suction

pressure, flow meter on, Main Relief Valveopen, Low/High Pump Room temperature, Low

fuel level, Others )

DIESEL CONTROLLERS


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Pump Maintenance


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Pump MaintenancePump acceptance tests are defined in NFPA20

Chapter 11Inspection and maintenance are defined in NFPA25Chapter 5Seals and bearings are the highest maintenance itemfor a pumpThe packing should be checked and adjusted eachtime the pump is tested

As fire pumps do not run often, bearings should bechecked for cleanliness and to ensure that adequateoil or grease has been applied (depending on the typeof bearing)Motor bearin s should also be checked


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