nfpa 291 hyd_test.pdf

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Confidence TestingFire Hydrants

A Guide to the Maintenance, Testing, and Marking ofPrivate Fire Hydrants

Colorado Springs Fire DepartmentOffice of the Fire Marshal

July 19981st Edition

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IntroductionThe city of Colorado Springs has nearly 12,000 fire hydrants within its city limits. More than aquarter of these are private hydrants. What this means is that the city is responsible formaintaining less than 75% of a critical fire protection system that the Fire Department relies uponto effectively fight fires within its jurisdiction.

How can you tell a private hydrant from a public one? Chances are if the hydrant is not identifiedby an alpha-numeric code on the bonnet, it is a private hydrant. Also, public hydrants can only belocated in the public right-of-way, on the side of public streets, or any other public property.Hydrants located in the middle of commercial parking lots are more than likely private hydrants.

The testing, maintenance, and marking of hydrants is the responsibility of the property owner. Itis imperative that this be accomplished by a competent individual or group, therefore we highlyrecommend the hiring of a contractor knowledgeable in this field. As of January 1, 2000, themaintenance, testing, and inspection of private hydrants may be performed only by an FSC-Hlicensed contractor or individual. If circumstances warrant, a business may train and certify itsown people to undertake this responsibility. Please note that in any case, the property ownerassumes all liability not otherwise contractually dictated for the proper operation, maintenance,and marking of its hydrant system(s).

A guide for the fire flow testing and marking of hydrants can be found in the National FireProtection Association (NFPA) Standard 291: “Recommended Practice for Fire Flow Testing andMarking of Hydrants.” The maintenance and periodic testing of hydrants is covered in NFPAStandard 25: “Standard for the Inspection, Testing, and Maintenance of Water-Based FireProtecting Systems.” Specifically, Chapter 4 of this standard addresses private water mains andtheir appurtenances. Additionally, an outstanding reference guide on this is the American WaterWorks Association (AWWA) Manual M-17 “Installation, Field Testing and Maintenance of FireHydrants.”

ScopeThis information packet is intended to aid the informed and competent do-it-yourselfer with theproper maintenance, testing, and marking of private fire hydrants for businesses in the city. In noway will this packet attempt to replace proper training and experience, and therefore, should notbe viewed as a training manual, but as a guide to the equipment and expertise required for theproper execution of these functions.


Part I: Regular Maintenance

Fire hydrants spend most of their time unusedand ignored, yet they are called upon in amoment’s notice to provide fire flow for theprotection of a business or home. They are anindispensable facet of the overall fireprotection features of a building.

Because of the way land is platted andeasements are granted, there exist in excess of

3,000 private hydrants within the city ofColorado Springs.

These hydrants are required for the fireprotection of a building, but they are uselessunless regularly maintained. Furthermore,they should be painted as described in Part IIIso that firefighters can quickly identify thesystem capability.

Anatomy of a Typical Dry HydrantAll hydrants in this part of the countryare dry hydrants because of thefreezing weather conditions weexperience. This means that the barrelof the hydrant stays dry until thehydrant is opened at the Operating nut.This drives the stem to open the valveat the bottom of the barrel. Notice inthe detail to the left that the stem issplit into two parts with a safetycoupling which acts as a breakawayvalve in case the hydrant is run over.

As can be seen, a hydrant is anintricate water delivery mechanismswith many moving parts.

In addition to the stem and valve thatbring water into the barrel, otherimportant moving parts are the 2½ inchand 4½ inch nozzle caps (identified ashose and pumper nozzle respectively)which keep the nozzles protected fromdirt and the elements. The caps caneasily lock up due to corrosion,neglect, and sloppy painting

Regularly Scheduled MaintenanceIt really doesn’t take much to keep ahydrant operating in peak condition.But regular maintenance must befollowed. NFPA 25 “Standard for theInspection, Testing, and Maintenanceof Water-Based Fire ProtectionSystems” is the standard for thatshould be used for the periodicmaintenance and testing of hydrants. .

Lock washerOperating nutWeather capHold down nut “O” ringBonnet “O” ringHold down nutOil filter plugBonnetBonnet gasket“O” ring packingBonnet boltPumper nozzlePumper nozzle capHose nozzlePumper nozzle gasketHose nozzle capHose nozzle gasketNozzle cap chainUpper barrelUpper stemSet screwSafety sleeveSafety stem couplingSafety flange gasketSafety flangeSafety flange boltLower stemLower barrelDrain valve facingDrain valve facing screwUpper valve plateShoe gasketShoe boltSeat ringMetallic gasketMain valveLower valve plateValve plate nutCap nutShoe hydrant lubricatingoil


Chapter 4 indicates that hydrants must beinspected, lubricated, and flow testedannually.

InspectionThis should be done annually or after eachuse in conjunction with the maintenance andthe flow test.

Check the hydrant’s appearance. Removeobstructions around it within a 3 ft radius.Check to see whether the hydrant needs tobe raised because of a change in the groundsurface grade. If adjustments are needed,schedule the work.

Inspect the hydrant for leaks, either fromthe operating nut, nozzle caps, or the drain.

Remove all nozzle caps and check threadsand operating nuts for damage.

Make repairs as necessary.

MaintenanceIn conjunction with regular inspections, thefollowing maintenance should be performedannually. Loosen one outlet-nozzle cap to allow air to

escape. Open the hydrant only a few turns. Allow

air to vent from the outlet-nozzle cap. Tighten the outlet-nozzle cap. Never use

excessive force. Open the hydrant fully. Check for ease of

operation. Check for leakage at flanges, around outlet

nozzles, at packing or seals, and around theoperating stem. Repair as needed.

Partially close the hydrant so the drainsopen and water flows through underpressure for about 10 seconds, flushing thedrain outlets.

Close the hydrant completely. Remove anoutlet-nozzle cap and check the operationof the drain valve by placing the palm ofone hand over the outlet nozzle. Drainageshould be sufficiently rapid to createnoticeable suction.

Remove all outlet nozzle caps, clean thethreads, check the condition of the gaskets,and lubricate the threads with amanufacturer approved lubricant. (Thereare several never-seize compoundsavailable) Check the ease of operation ofeach cap.

Check outlet-nozzle-cap chains or cablesfor free action on each cap. If the chains orcables bind, open the loop around the capuntil they move freely. This will keep thechains or cables from kinking when the capis removed during an emergency.

Replace the caps. Tighten them, and thenback off slightly so they will not beexcessively tight. Leave them tight enoughto prevent their removal by hand.

Check the lubrication of operating-nutthreads. Lubricate per the manufacturer’srecommendations.

Locate and exercise the auxiliary valve.Leave it in the open position.

Check the breakaway device for damage. If the hydrant is inoperable, bag it with a

brightly colored, weather-resistive coverthat bears the stenciled warning:“HYDRANT OUT OF SERVICE”.Schedule the hydrant for repair.

Flow TestsThere are two different types of flow tests.The first is a simple flushing of the hydrant,which will be covered below. The second is aflow test for the determination of fire flow.This type of test is described in Part II of thispacket.

Flushing a hydrant removes any accumulatedsediment in the barrel and on the valve. It isrecommended that flushing be performedannually along with the regular inspection andmaintenance items described above. In anycase, these should always be performed priorto flushing.

Circumstances will sometimes not permitflushing; at minimum, perform the regularinspection and maintenance.


To flush a hydrant:

Contact the Water Resources Department toinform them that a flow test is about to takeplace. Often, when a large volume of wateris moved through an orifice such as ahydrant, sediment in the line will be stirredup and the Water Resources Departmentwill receive complaints about brown water.

Prepare to flow water from the hydrant.Decide if a diffuser or hose will benecessary to direct the flow of water awayfrom landscaped or other areas. Lay outhose, if necessary. Connect the necessaryhardware to the nozzle;

Open the hydrant very slowly until it isfully open;

Let water flow for a minimum of 3 minutesor until water is clear. Avoid opening morethan one hydrant at a time unless you aredoing a test as described in Part II. Thiswill minimize the amount of flow created inthe main;

Shut the hydrant down, again very slowly,until the valve is completely shut;

Remove hardware and replace cap.

Dynamics of WaterWhen performing any sort of flow test orexercising of hydrants, there are severalimportant concepts that must be understood toavoid causing damage to the hydrants and tothe water system in general.

Water HammerWater hammer is caused by an abrupt changein the velocity of flowing water. It is mostoften the result of shutting down a valve tooquickly. Imagine driving into a brick wall at 60mph. The energy of your momentum has to betransferred somewhere. In this case it isshared, though unequally, by you, the car, andthe brick wall.

Water is incompressible. It will not absorbANY of the energy it gives off by being forcedto suddenly decelerate. Therefore, the system,

pipes, hydrants, ground have to absorb all ofthe energy.

If a valve is shut down too quickly, the weaklink in the system will go first. The weak linksare almost always at the flanges.

Brown WaterBrown water is the basic complaint the WaterResources Department receives when peopleturn on their faucet and see less than clearwater coming out. This may be caused byseveral things. One thing that will almostalways cause brown water is a large amount offlow in a water main.

During normal conditions only the centerportion of a water main actually flows water.That’s because of the friction that the wall ofthe pipe is exerting on the water. It’s lesstrouble for the center portion to flow than theouter portion.

As the average velocity increases, so will thevelocity of the fluid close to the wall of thepipe. As this water moves faster, it begins tokick up all the sediment that usually stays at thebottom of the pipe. This sediment gets stirredup and does not settle back down until thevelocity slows down.

However, once the sediment has been kickedup into the center portion of the pipe, it is nowin the main stream of flow.

Protection from Vehicular DamagePlease refer to the CSFD handout titled“Protection from Vehicular Damage” for helpin designing vehicle protection such as bollardsfor fire hydrants or other devices such as PIVsor fuel tanks.


Part II. Fire Flow TestingFire flow testing is the determination of actualflow conditions within a hydrant system. Ahydrant system is the system of mains,whether looped or not, capable of providingfire flow to a site. A site may have one ormore hydrant systems with different flow andpressure characteristics. Consult a water mapor your utility plan to determine how manysystems feed your site.

Available fire flow is measured in gallons perminute (gpm) at a residual pressure of 20 psi.

EquipmentTo properly test a hydrant system, you willneed to following equipment and materials:

Equipment Quantity2½” Cap gauges 250 ft section of 3” and/or 5”hose*

2 - 4

Allen wrench(check manufacturer for size)

1

Clipboard 1Diffuser* 1Hydrant wrench 2Landscape protection* -Paint supplies(spray paint & masking tape)

-

Pitot tube and gauge 1Record keeping material -Ruler to measure inside diameter 1Scientific calculator 1Steel brush 1Thread grease (lubricant)(Check manufacturer for specs)

-

Valve key 1Water distribution map 1

*The diffuser, landscape protection (mat), andhose are optional items that are not absolutelynecessary for the testing of hydrants, but areoften advantageous to have if you do not wantto disturb landscaping. FLOWING WATERWILL TEAR UP GRASS.

NOTE: Additional flow hydrants will requireadditional equipment. The quantities listedabove are minimums.

Setup Decide which hydrant will be your pressure

hydrant and which will be your flowhydrant(s). The pressure hydrant will beused to measure Static pressure andResidual pressure. It should be closer to afeed main than the flow hydrant. SeeFigure II-1 to the right.

Decide how many flow hydrants to use. Asa rule of thumb, you should flow enoughhydrants at the same time such that theresidual pressure drops at least 10% fromthe static pressure.

For example, you take a static pressure of140 psi from the cap gage. When you opena hydrant, the pressure drops to 135 psi.You either need to open another hydrant orthe steamer (4½ inch) connection.

Contact the Water Resources Department

and inform them that a test is about to takeplace. Call all three phone numbers onfound in Section IV of this packet.Unfortunately, there is not one singlenumber that will notify all the people thatneed to know water may be flowing.

You may get turned down in your requestto flow water during peak flow times of theday (early in the morning until 10 am orafter 4 pm in the evening during thesummer.)

Locate and perform the following on thepressure hydrant:

Flush as indicated in Part I; Install the cap gauge;

Loop

Pressure hydrant(Choose either)

Flow hydrant(s)

Main

Figure II-1: Hydrant flow layout


Open the hydrant slowly and fully; Read and record the pressure. This is

the Static Pressure. Locate and perform the following on the

flow hydrant(s):

Record the inner diameter of the nozzlewhich will be flowed;

Insert a hand into the nozzle openingand feel the entrance shoulder todetermine the nozzle coefficient (0.9 fora smooth rounded shoulder, 0.8 for asquare shoulder, and 0.7 for a nozzlethat protrudes into the barrel);

Install and arrange any hoses ordiffusers necessary to minimize effecton traffic or landscaping;

Flow TestAt this point it would be helpful to have oneor more assistants and a reliable method ofcommunication such as two-way radios toperform an efficient test.

Open each flow hydrant slowly and fully.Open one hydrant at a time to avoid apressure surge;

Wait for the pressure at the pressurehydrant to stabilize, read and record thispressure. This is the Residual Pressure.Then signal the persons stationed at theflow hydrants to take pitot readings, or goand takes readings yourself. The readingsfor residual pressure and the pitot readingsshould really be taken at the same time foran accurate flow.

To take a pitot reading, hold the pitot gaugeapproximately ½ of the diameter away fromthe nozzle in the center line of the nozzle.Read and record this pressure. This is yourPitot or velocity pressure.

If sediment appears, continue to flow wateruntil the main has been flushed.

Close each flow hydrant, one at a time,very slowly. Closing a hydrant too fastwill cause damage to the hydrant or to

water mains. Refer to Water Hammer onpage 5 for an explanation.

Perform calculations as described under theEquations section below. If a residualpressure is unusually low, there may be aclosed valve which will need to be openedfor an accurate flow test.

Repeat these steps if necessary.

There may be certain circumstances whenthere is only one hydrant, and a pressurehydrant cannot be located, or is too fardown the line for an accurate measurement.In this case, use on 2½ inch outlet for thepressure readings, and the other 2½ inch orsteamer cap for the flow readings. The capgauge reading may fluctuate more in thiscase due to turbulence.

EquationsTypically, residual pressures in ColoradoSprings are in excess of 50 psi, especially innewly developed part of town. Fire flow,however is measured consistently at 20 psi.In order to get the fire flow in gallons perminute (gpm) at 20 psi, the equations belowwill need to be performed.

A scientific calculator is useful in performingthese equations. A standard calculator maybe used to estimate where the 0.54 power istaken as a square root. Basic algebraic skillsare required to perform these functions.

The following equations are used todetermine fire flow based on the static,residual (flowing), and pitot pressures:

Q c D Pr d p= 29 83 2. (Eq. 1)

Q QPP Pf r

s

s r=

−−

⎛⎝⎜

⎞⎠⎟

200 54.

(Eq. 2)

where:Qr is the residual flow at the pitot pressure

measured in gpmcd is the friction loss coefficient (usually 0.9

for a smooth 2½” opening)D is the diameter of the opening in inchesPp is the pitot pressure in psi


Qf is the FIRE FLOW in gpm at 20 psiPs is the static pressure in psiPr is the residual pressure in psi

ExampleYou perform a hydrant test and gain thefollowing results:Ps (Static pressure) = 140 psiPr (Residual pressure) = 125 psiPp (Pitot pressure) = 120 psicd = 0.9 because the inside of the nozzle wassmooth.D = 2.5 inches

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):

= 1876140 20140 125

0.54

, ×−−

⎛⎝⎜

⎞⎠⎟

= 187612015

0 54

,.

×⎛⎝⎜

⎞⎠⎟

= ( )1876 8 0 54, .× (raise 8 to the 0.54 power)= 1,876 × 3.07375= 5,766 gpm

That system has the capacity to flow 5,766gallons per minute at 20 psi residual pressure.

Record KeepingRefer to Appendix A for forms to use to keeprecords of these flow tests. Copies of thesetests should be sent to the Office of the FireMarshal and the original kept by the owner ofthe private property. It is also a good idea tokeep copies on site at an appropriate address.

FrequencyIt is a requirement of NFPA 25 thatinspection, maintenance, and flushing asoutlined in Part II of this packet be performedannually.

We recommend that fire flow testing beperformed every 5 years to ensure integrity ofthe system.


Part III. Marking of HydrantsThe marking of hydrants is important for tworeasons. First, it immediately tells fire crewsthe capacity of the fire main system they arehooking into. Second, it shows that the owneris complying with this program.

Historically, fire crews have trusted publichydrants above private ones, because the cityhydrants are on a routine maintenanceschedule, and, generally, the likelihood ofrunning into problems is lessened.

This contradicts the whole reason forrequiring hydrants in the first place.

Hydrant Colors - Painting RequirementsThe following color designations are based onNational Standard1 as well as a localamendment to that standard. BecauseColorado Springs has such excellent water, anew category was created for hydrant systemscapable of delivering more than 3,000 gpm.

The Water Resources Department paints allpublic hydrants a certain color based on theavailable fire flow measured at 20 psi residualpressure under maximum day demandconditions. The table below shows thesedesignations.

Fire Flows (gpm) Color Painted on:0 - 499 Red Bonnet

500 - 999 Orange Bonnet1,000 - 1,499 Green Bonnet1,500 - 3,000 Blue BonnetAbove 3,000 Blue Bonnet &

Steamer Cap- Yellow Barrel

Private hydrants are required to be painted tothis color scheme depending on actualmeasured fire flow at 20 psi. The measuringof this flow is described in Part II of thisPacket.

1 NFPA 291, Sec 3-2: Marking of Hydrants

Bonnet

Steamer Cap(4½ in. outlet)

Barrel

Hydrant Paint Scheme Example

For assistance in choosing the actual colorsused by the Water Resources Department, wehave included the manufacturers andspecifications for the paint used on publichydrants.

This table is provided solely for yourconvenience and is not intended to imply thatonly these manufacturers’ products would beacceptable. Any manufacturer’s product thatis equivalent in color and quality to thesementioned below would be acceptable for thepurpose of hydrant identification.

Color Manufacturer Specification

Red Rustoleum Safety Red#2163

Orange Aervoe Orange #305

Green Aervoe Fluor Green #184

Blue Aervoe Ford Blue #560

Yellow Rustoleum EquipmentYellow #2148

NOTE: It is very rare that you will have topaint a hydrant red or orange. If youcalculate a flow of 1,000 gpm or less, recheckyour math then inform the Water ResourcesDepartment. It may be a closed valve.


Part IV. ReferencesThe following phone numbers will be ofvaluable use to you in acquiring additionalinformation or in performing the dutiesoutlined in this packet.

Water Resources Department:

Dispatch – 448-4200

Construction – 448-4570

Lab – 448-4560

National Fire Protection Association

(800)344-3555

American Water Works Association

(800)926-7337

Nomenclaturegpm gallons per minute

psi pounds force per square inch

BibliographyInstallation, Field Testing, and Maintenanceof Fire Hydrants, AWWA Manual M17,Third Edition, American Water WorksAssociation, 666 West Quincy Avenue,Denver, CO 80235

NFPA 25, Standard for the Inspection,Testing, and Maintenance of Water-BasedFire Protection Systems, 1995 Edition,National Fire Protection Association, 1Batterymarch Park, PO Box 9101, Quincy,MA 02269-9101.

NFPA 291, Recommended Practice for FireFlow Testing and Marking of Hydrants, 1995Edition, National Fire Protection Association,1 Batterymarch Park, PO Box 9101, Quincy,MA 02269-9101.

The Fire Protection Handbook, 18th Edition,National Fire Protection Association, 1Batterymarch Park, PO Box 9101, Quincy,MA 02269-9101.

Appendix A


COLORADO SPRINGS FIRE DEPARTMENTConfidence Testing

Fire Hydrants and Water Supply

Address: Hydrant Location:

Business Name:

Inspected by: Date Tested:

Prior to conducting water flow tests, notify the Water Resources Department: Construction (448-4570), Dispatch (448-4200), and Laboratory (448-4560).

Recorded Pressures and Flows

Static: psi Diameter: inchesResidual: psi Residual Flow: gpmPitot: psi Flow at 20 psi: gpm

General

1. Underground shutoff valves fully operated. Yes [ ] No [ ]

2. All vegetation, landscaping, and other obstructions are at least three Yes [ ] No [ ]feet away from hydrants.

3. All threaded protective caps are easily removed. Yes [ ] No [ ]

4. All threaded connections are undamaged and seals in good condition. Yes [ ] No [ ]

5. All threaded connections are lubricated with appropriate lubricant. Yes [ ] No [ ]

6. Operating stem nuts are not damaged or stripped. Yes [ ] No [ ]

7. Hydrants flushed at full capacity until flowing water is clear. Yes [ ] No [ ]

8. When closed, hydrants drain properly, suction can be felt. Yes [ ] No [ ]

9. Hydrant was used as part of a fire flow test Yes [ ] No [ ]

10. Hydrant is painted appropriate color for fire flow. Yes [ ] No [ ]

If hydrant must be taken out of service, notify the Fire Department Communications Center (444-7000) and the WaterResources Department Dispatch Center (448-4200).

General Comments

Problems Found:

Corrections Made:

This is to certify that all fire hydrants and water supply have been inspected and tested for reliability and all necessarycorrections have been made.

Signature of tester:

Agency: Telephone: This report shall be completed in duplicate. A copy shall be left at the premises for Fire Department inspection andone copy shall be forwarded to:

Colorado Springs Fire DepartmentOffice of the Fire Marshal

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