5()Cross-Connection

auestions,Answers,

& lllustrationsRelating To

Backflow Prevention Productsand

Protection ofSafe Drinking Water Supply

U.S.A: 81 5 Chestnut St., No. Andover, l\4A 01 845-6098; www.wattsreg.com

Canada: 5435 North Service Rd., Burlington, 0NT, L7L 5H7;wwry.wattscanada.ca

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What is back-siphonage?Back-siphonage is the reversal of normal flow in a systemcaused by a negative pressure (vacuum or partial vacuum)in the supply piping.

Gl What factors can cause back-siphonage?

Z Back-siphonage can be created when there is stoppageof the water supply due to nearby fire-fighting, repairs orbreaks in city main, etc. The effect is similar to thesipping of a soda by inhaling through a straw,which induces a flow in the opposite direction.

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-? What is backpressure backftow?19Backpressure backflow is the reversal of normal flow inasystem due to an increase in the downstream pressureabove that of the supply pressure.

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Back pressure-backflow is created whenever thedownstream pressure exceeds the supply pres-sure which is possible in installations such as heating systems,elevated tanks, and pressure-producing systems. An examplewould be a hot water space-heating boiler operating under '15-20

lbs. pressure coincidental with a reduction of the city water sup-ply below such pressure (or higher in most commercial boilers). Aswater tends to flow in the direction of least resistance, a backpres-sure-backflow condition would be created and the contaminatedboiler water would flow into the potable water supply.

What is a cross connection?A cross connection is a direct arrangement of a piping linewhich allows the potable water supply to be connected toa line which contains a contaminant. An example is thecommon garden hose attached to a sill cock with the endof the hose lying in a cesspool. Other examples are agarden hose attached to a service sink with the end of thehose submerged in a tub full of detergent, supply linesconnected to bottom-fed tanks, supply lines to boilers.

What is the most common formof a cross connection?lronically, the ordinary garden hose is the most commonoffender as it can be easily connected to the potablewater supply and used for a variety of potentially danger-ous applications.

,7 Z What is potentially dangerous aboutf an unprotected sill cock?

The purpose of a sill cock is to permit easy attachmentof a hose for outside watering purposes. However, agarden hose can be extremely hazardous because theyare left submerged in swimming pools, lay in elevatedlocations (above the sill cock) watering shrubs, chemi-cal sprayers are attached to hoses for weed-killing,etc.; and hoses are often left laying on the groundwhich may be contaminated with ferlilizer, cesspools,and garden chemicals.

What protection is requiredfor sill cocks?

A hose bibb vacuum breaker should be installed on every sill cockto isolate garden hose applications thus protecting the potablewater supply from contamination.

Should a Hose Bibb Vacuum Breakerbe used on frost-free hydrants?Definitely, providing the device is equipped with means to permitthe line to drain after the hydrant is shut-off. A "removable" type

"- hose bibb vacuum breaker could allow the hydrant to be drained,but the possibility exists that users might fail to remove it fordraining purposes, thus defeating the benefit of the frost-proofhydrant feature. lf the device is of the "Non-Removable" type,be sure it is equipped with means to drain the line to preventwinter freezing.

f1 What is an Atmospheric Vacuum Breaker?

Hose Bibb Vacuum BreakerWatts 8

Hose Bibb Vacuum Breakerfor Frost-Proof Hydrants

Watts NF8

Atmospheric Vacuum BreakerWatts 2884

I O ;Hil:.,tH""',tl,i:li'"tT';';lJf, ilil?'u u m

Theoretically yes, but practically no. An anti-siphon vacuumbreaker must be elevated above the sill cock to operate properly.This would require elevated piping up to the vacuum breaker anddown to the sill cock and is normally not a feasible installation.On the other hand, a hose bibb vacuum breaker can beattached directly to the sill cock, without plumbing changes andat minor cost.

The most commonly used atmospheric anti-siphon vacuum break-ers incorporate an atmospheric vent in combination with a checkvalve. lts operation depends on a supply of potable water to sealoff the atmospheric vent, admitting the water to downstreamequipment. lf a negative pressure develops in the supply line, theloss of pressure permits the check valve to drop sealing the orificewhile at the same time the vent opens admitting air to the systemto break the vacuum.

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installed, it will protect the potable water supply.The device shall be installed 12" above thehighest sprinkler head.

What is continuous pressure?

This is a term applied to an installation in whichthe pressure is being supplied continuously to a backflowpreventer for periods of over 12 hours at a time. Laboratoryfaucet equipment, for example, is entirely suitable for a non-pressure, atmospheric anti-siphon vacuum breaker because thesupply is periodically being turned on and shut off. A vacuumbreaker should never be subjected to continuouS ,,pressure unless it is of the continuous pressure type Eand clearly identified for this service. .<=

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a 6 Will an Anti-Siphon Vacuum Breaker protectI Z against a backpressure backflow condition?

Absolutely not! lf there is an increase in the downstream pressureover that of the supply pressure, the check valve would tend to"modulate" thus permitting the backflow of contaminated water topass through the orifice into the potable water supply line.

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Yes, if these are properly installed, they will protectthe potable water supply. The device shall beinstalled 6" above the highest sprinkler head andshall have no control valves located downstreamfrom the device.

Can an Atmospheric Vacuum Breakerbe used under continuous pressure?

No! codes do not permit this as the device could become"frozen", and not function under an emergency condition.

Can a Pressure Vacuum Breaker be usedon a multi-zone lawn sprinkler system?

Yes. This type of vacuum breaker can be used undercontinuous pressure. Therefore, if properly

Sprinkler Heads

ZoneShutoff Valve /

Zone Control Valve

Multi-Zone System

16

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Most jurisdictions require backflow protection on all boiler feedlines. Some will allow a backflow preventer with intermediate ventas minimum protection for residential boilers. A reduced pressurebackflow preventer is generally required on commercial andcompound boilers. However, low cost, continuous pressurebackflow preventers are now available which will perform withmaximum protection; thus check valves are not recommended.

Anti-Siphon

VacuumBreaker

,. Pressure Vacuum Breaker

Sprinkler Heads

Single Zone System

Chicken House

r I 8 Hl":#,t*'Titffi?'e between porrution

Pollution of the water supply does not constitute an actualhealth hazard, although the quality of the water isimpaired with respect to taste, odor or utility. Contami-nation of the water supply, however, does constitute anactual health hazard; the consumer being subjected topotentially lethal water borne disease or illness.

1 9 Hi3:JiiT:ffi"##,i,1l'l',','J.';'ftll'.lo%ry,Chicken House Cross-Connection, Spring 199'1. ln response toa complaint from a customer on the Casa Water System (PerryCounty), a staff member of the Division of Engineering foundthat the water systems had been contaminated by backflowfrom chicken houses. The water system connected to thechicken houses included two single check valves in seriesfor backflow prevention purposes. The water was beingused to administer an antibiotic solution to the chickens.

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21

22 y*:il:::#H:::;T:'nT:::'*::;:i""" . :8reports but because of the possibility of litigation for pending \^ \4'i(/repons ()ul oecause oI Ine posslolllly OT llllgallon TOr penolng V. \j/-i*v::-,cases, information can be difficult to obtain. However, in San - \{14-q'l / ,Francisco, an industrial plant had a submerged water inlet \f o.-o 'qBrz

supplying a lye vat. lmmediately adjacent to this installation was t ?'b*i-tD4the employee's shower room. Officials fortunately discovered the \|y (Sll'icross connection, but were alarmed that employees could potentially '\ '

be bathing in water contaminated with lye from the vats.

AntibioticSolution

PrivateWell

On or about the week of the 14th of May, 1991 , a back-siphonageproblem occurred. A local farmer reported the problem on his farm.He was filling a spray tank on his farm with water and 2-4-D. Thewind kept blowing the fill hose away from the fill spout so he extend-ed the hose down into the tank. As the tank filled, he went onto otherduties. He went into the house for some reason and his wife told himthat the water had become salty tasting. He immediately thought oflhe 2-4-D and went to the tank and it had began siphon-ing waterfrom the tank. He told his wife not to use any more water. An artesianwell, (free flow)was filling the tank. The artesian well also suppliedwater to the home through a storage tank and pump system. As thespray tank was filling, the pump in the house came on and createda pull on the well greater than the pressure at the well head. Conse-quently, as the pump was on, it was also pulling lhe 2-4-Dand water from the spray tank.

Are there any records of recent cases involvingunprotected cross Connections?The startling fact is that cross connections continue to occur andthere are documented cases involving reverse flow. For other cases,request folder F-SBN.

UnapprovedSingle CheckValves

-€Backflow fromGhicken House

Chicken House Cross-Connection, Spring 1991

Watts 800 SeriesVacuum Breakershould have been

lnstalled Here

PublicWater pSupply

Water Supplyfrom Free FlowArtesian Well

Pump andSupply Tank lorWater Supply to

House

2-4-D Backsiphonage Case

5

Spray Tank withWater and 2-4-D

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oit foufs w"t"fi;,ty

to stayawayfromwater

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23 Y'1*:1se was renorted involving

Most people are familiar with the details of the HolyCross FootballTeams' "hepatitis" incident, which waslater determined to be caused by a backflow of con-taminated water. lt took close to nine months forofficials to determine that a severe fire in nearbyWorcester lowered the pressure in the footballfield area to the pointwhere a back pressure backflow condition was created allowingcontaminants from a sunken hose bibb pit to backflow into the fieldhouse drinking bubbler.

24 lHr::ffi fi rfi rted invorvins

25

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Much to the surprise of the customers of a bank in Atlanta, Georgiathey saw yellow water flowing from drinking fountains and green icerolling out of cafeteria dispensing machines.It was later reported that a pump, used for the air conditioningsystem, burned out; and a maintenance man, unaware of the danger,connected the system to another pump used for potable water.The result caused large doses of bichromate of soda to be forcedinto the potable water supply, causing the dramatic appearanceof yellow water and colored ice cubes.

Are there any cases involving outsideprocessing activities?Yes, a case occurred in a gravel pit operation inlllinois. A pump was used in the processing opera-tion supplying 100 lbs. pressure. Contaminatedwater was forced back through an unprotected"prime line" overcoming the city water pressure of45 lbs. The contaminated water entered the citymain and was channeled into a nearby bottlingplant. This probably would have gone undetectedexcept that personnel in the bottling plant noticedthat the water was not only dirty but was warm.City officials were immediately called which led tothe discovery of the reverse flow from the gravel pit operation.

Wash .^.Return \/

11/z "Water*

Service

6" PumpDischarge

Pump 50 gpm@ 100 psi

26 Unwanted Guests (Residents find parasites in tap water) Oct. 1991 .

Parasitical worms were found in the water at two homes after amalfunctioning lawn sprinkler coupled with a water main breaksucked the nematodes into the water system.The nematodes first showed up in the evening ofOct. 1 after the backflow prevention system on theprivately owned underground sprinkler malfunc-tioned. When the water pressure dropped, thevacuum in the system sucked some water from thesprinkler into the city water.

A homeower found the worms swimming around in his bathtubwhen he stafted filling the tub for his child. He said he wasappalled to find the critters, as well as rust and other debris in hiswater. "The only reason I noticed it is because I have children andwas giving my kid a bath. lf you have a screen on your faucet or you

. were taking a shower, you wouldn't see it."b

What other typical cases have been reported?

Main

I

Jlmproperlylnstalled

AVB<

Blick Home

SiphonEffect

pump priming t-ine selimentation Basins

Netherwoods St.

Health HazardNon-Health

Hazard

9O9AG

J#\I

Watts

ffiild

-The contractor who installed the sprinkler system didn't pull a citypermit and used a "cheap" atmospheric vacuum breaker. When itmalfunctioned, which was at the time of the water main break, thenematodes were pulled right in.

ln Utah, a doctor repofted two gold fish flowing into his bath tub.Earlier in the day he had been filling his gold fish poolwith a gardenhose when a back-siphonage condition developed resulting in thelate emergence of the gold fish into the bath tub.

What is significant, however, is the number of recent casesthat are not reported. The number of unprotected crossconnections in existence are potential disasters which canoccur any time unless adequate protective devicesare installed.

4|-, What is meant by "Degree of Hazard"?

Z I rhe degree of hazardis a commonly used phraseutilized in cross connection programs and is simply adetermination on whether the substance in the non-potable system is toxic (health hazard) or non-toxic (non-health hazard).

28 What is the difference between a toxicand a non-toxic substance?

Toxic substance is any liquid, solid or gas, which whenintroduced into the water supply creates, or may createa danger to health and well-being of the consumer. Anexample is treated boiler water. A non-toxic substance is

any substance that may create a non-health hazard, is anuisance or is aesthetically objectionable. For example,food stuff, such as sugar, soda pop, etc. Therefore, youmust select the proper device according to the type ofconnection and degree of hazard. There are five basicproducts that can be used to correct cross connection.

29 What are the five basic products usedfor protection of cross connections?

The five basic products are:1. Air Gap2. Atmospheric Vacuum Breakers -which also includes hose

connection vacuum breakers3. Pressure Vacuum Breakers - which also includes backflow

preventer with intermediate atmospheric vent for1/2" and 32" lines

4. Double Check Valve Assembly5. Reduced Pressure Zone Assembly

^ 30 H::: :,lJ,iljj1lo'",.",." of the potab,e and non-/ potable system by an air space. The vertical distance

between the supply pipe and the flood level rim should betwo times the diameter of the supply pipe, but never lessthan 1". The air gap can be used on a direct or inlet connec-tion and for all toxic substances.

a { Where is an Atmospheric Vacuum Breaker used?

f, t Armospneflc vacuum Breaxers may oe useo onry on connecnons roa non-potable system where the vacuum breaker is never subjectedto backpressure and is installed on the discharge side of the lastcontrol valve. lt must be installed above the usage point. lt cannotbe used under continuous pressure. (Also see No. 1'1)

Where is a Hose Bibb Vacuum Breaker used?

Hose Bibb Vacuum Breakers are small inexpensive devices withhose connections which are simply attached to sill cocks andthreaded faucets or wherever there is a possibility of a hose beingattached which could be introduced to a contaminant. However,like the Atmospheric Vacuum Breaker they should not be usedunder continuous pressure.

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33 Where is a Pressure Vacuum Breaker used?

Pressure Vacuum Breakers may be used as protection for connec-tions to all types of non-potable systems where the vacuum break-ers are not subject to backpressure. These units may be usedunder cqntinuous supply pressure. They must be installed abovethe usage point. (spill resistant models for indoor use are alsoavailable).

Where is a Double Check Valve Assemhly used?

A double check valve assembly may be used as protectionof all direct connections through which foreign materialmight enter the potable system in concen-tration which would constitute a nuisanceor be aesthetically objectionable, such as air,steam, food, or other material which does notconstitute a health hazard.

Watts 8

Watts 9D

3 4 Hl"J:rf; "1,':uu'Sl"#r

revente r w i th I n te r med i ate

These devices are made for 1/2" and 3/q" lines and may be used onnon-health hazard cross connections. They are suitable for useunder continuous supply pressure and possible protection againstbacksiphonage or backpressure backflow

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Watts 007QT-S

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Where is a Reduced Pressure ZoneAssembly used?

Reduced Pressure Zone Assemblies may be used onall direct connections which may be subject tobackpressure or back-siphonage, and where there is the possibilityof contamination by the materialthat does constitute a potentialhealth hazard.

What are typical applications for an Air Gap?

Because today's complex plumbing systems normally requirecontinuous pressure, air gap applications are actually in the minor-ity. lt should be remembered, however, that whenever a pipingterminates a suitable distance above a contaminant, this itself isactually an air gap. Air Gaps are frequently used on industrialprocessing applications, but care should be taken that subsequentalterations are not made to the piping which would result in adirect connection.

Watts 909QT-S

40

Fixture or Appliance

3 I y'i1lil;ll1'f3jiP R I i cati o n s ro r Atm os p h e r i c

Atmospheric Vacuum Breakers can be used on most inlet typewater connections which are not subject to backpres-sure such as low inlet feeds to receptacles containingtoxic and non-toxic substances, valve outlet or fixturewith hose attachments, lawn sprinkler systems andcommercial dishwashers.

3 9 f"if,';:iy#t?L:PPrications ror Hose

Hose Bibb Vacuum Breakers are popularly used on sill cocks,service sinks and any threaded pipe to which a hose may potentiallybe attached.

What are typical applications for PressureVacuum Breakers?

These applications should be similar to the Atmospheric VacuumBreaker with the exception that these may be used undercontinuous pressure. However, they should not be subjectto backpressure.

What are typical applications of Back-flow Preventer with Intermediate Vent?

For 1/2" and3/q" lines these devices are popularly usedon boiler feed water supply lines, cattle drinkingfountains, trailer park water supply connections andother similar low-flow applications. They will protectagainst both back-siphonage and backpressure andcan be used under continuous pressure.

Dishwasher

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42 Yjff ,:': ill'-'0ift['X:*'m JgBriefly, Double Check Valve Assemblies may be usedwhere the degree of hazard is low, meaning that the non-potable source is polluted rather than contaminated. Thedegree of hazard is oftentimes determined by local lnspectionDepartments and, therefore, such departments should be ques-tioned in order to comply with local regulations.

Reduced Pressure ZoneAssemblies?

This type should be used whenever the non-potablesource is more of a contaminant than a pollutant. Basically, theyare applied as main line protection to protect the municipal watersupply, but should also be used on branch line applicationswhere non-potable fluid would constitute a health hazard,such as boiler feed lines, commercial garbage disposal systems,industrial boilers, etc.

44 Are there any regulations in OSHAregarding cross connections?

Yes, OSHA requires that no cross connection be allowedin an installation unless it is properly protected with anapproved backflow preventer. These requirements arealso covered in B.O.C.A., Southern Std. BuildingCode, Uniform Plumbing Code and City, State andFederal Regulations.

What Standards are available \governing the manufacture of backflowprevention devices?

Standards such as ASSE (American Society of SanitaryEngineering), CSA (Canadian Standards Association),AWWA (American Water Works Association) , IAPMO (lnternationalAssociation of Plumbing Mechanical Officials), apply to most back-flow prevention products.

What is the benefit of a strainer precedinga backflow preventer?

A strainer will protect the check valves of a backflow preventerfrom fouling due to foreign matter and debris which may be flowingthrough the line. This not only protects the valve but eliminatesnuisance fouling and subsequent maintenance and shutdown. Theuse of a strainer with a water pressure reducing valve has been anaccepted practice for years. The amount of pressure drop attrib-uted to the strainer is negligible and is far outweighed by theadvantages provided by the strainer.

What are typical applications for Main

a

43 Watts 909

Air Gap

Branch Line Applications

Boiler Feed Lines

Boiler Fill

/uat e

45

46

10

47 What would cause a Reduced PressureZone Assembly to leak?

Leakage from a backflow preventer is normallyattributed to foreign matter lodging on the seatingarea of either the first or second check valve.Most times this can be corrected by simplyflushing the valve which will dislodge any loosepadicles. lt is, therefore, most impodant on newinstallations that the piping be thoroughly flushedbefore installing the unit. lt should be remembered,however, that spillage does providea "warning signal" that the valve is in needof maintenance.

ls periodic testing required for ReducedPressu re Zone Assembl ies?

NegativeSupply Pressure Back Pressure

?oWater-0ut Air-ln

48

49

Watts TK-DP

50

Yes, and this is to ensure that the valve is working properly and is arequirement of many states and cross connection control programs.Test cocks are provided on the valve for thispurpose and manufacturers are required to furnish fieldtesting information.

Should a backflow preventer be installed in thewater supply line to each residence?

Because of the growing number of serious residential backflowcases, many water purveyors are now requiring the installation ofapproved dual check valve backflow preventers at residential watermeters. They are also educating the public concerning cross con-nections and the danger of backflow into the local water supply.Since water purveyors cannot possibly be responsible for or monitorthe use of water within a residence, the requirements for these crossconnection control programs are increasing throughout the country.

What a cross connection controlproSram?

This is a combined cooperative effort betweenplumbing and health officials, waterworks compa-nies, property owners and certified testers toestablish and administer guidelines for controllingcross connections and implementing means toensure their enforcement so that the public potablewater supply will be protected both in the city mainand within buildings. The elements of a program

define the type of protection required and responsibil-ity for the administration and enforcement. Otherelements ensure continuing education programs.

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EXPoRT Hdqtrs.: Watts Regulator Co. 81 5 Chestnut St., North Andover, MA 01 845-6098 U.S.A. 978 688-1 8.1 1 978 794-1 B4B

Water Safety & Flow Gontrol Products

F-50 051 7

USA: 815 Chestnut St., No. Andover, IVA 01845 6098; wwv/.watts.com

Canada: 5435 Norlh Service Fd., Burlington, ONT. L7L 5H7; www.wattscanada.ca

@ Watts Regulator Company, 2006

864.10-07 @ Conodian Stondards Association

selection guide tr1T"?fiow preventers(See Clauses 5.3.1.1 and 5.4.1.)

Degree of hazard

CSATnre of Standard

Device undercontinuous

device designation Minor Moderate Severe pressure

Air gap

AVB 864.1.'l ,/ / !t* No

DCAP 864:3 / :/I Yes

DCAPC 864.3.1 ,/ ,/

DCVA 864.5 '/ ,/ Yes

'DuC 864;6

DuCV 864:8 '/ ,/I :- Yes

HCEVB . 8,64.2.1.1 ,/ ,/I /* No

HCVB 864.2 ,/ ,/t /* No

. LFVB 864.7 ' ,/ ,/l y'/* No

PVB 8G.1.2 / ,/ ,/ YCS

RP ts64.4 '/ { ,/ Yes

5RPVB 864.1.3 ,/ / ,/ Yes

*When the recommended backflow preventer is used for this degree of hozard, zoneproteclion with on RP bockflow preventer or on air gop shall also be required.

t When the recommbnded device is used for this degree of hozord, zone or areoprotection With a OCV{ backflow preventer, RP bockflow preventer, or an oir gap shatlalso be requirbd.

5.5 Backflow from fire protection systerns

5.5.rResidential "full flow through" fire protection systems in which pipe and fittings are made of materialsacceptable for potable water systems shall not require a backflow preventer.

s.5.2 :

Potable water connections to fire protection systerns (standpipe and sprinkler systems) shall be protectedagainst backflow caused by back siphonage or back pressure in accordance with the following (see

Table 3):(a) Reiidential "partial flow through" fire protection systems in which the pipe and fittings are made of

materials acceptable for potable water systems shall be protected by(i) a DuC backflow preventer complying with CSA 864.6; or(ii) a DuCF backflow preventer complying with CSA 864.6.1.

(b) Cf ass 1 fire protection systems that use no antifreeze or other additives of any kind and in which allpipes and fittings are made of materials acceptable for potable water systems shall be protected by(i) an SCVAF backflow preventer complying with CSA 864.9; or

luly 2007

@ Conadian Stondards Association Selection and instollation of backflow preventers

(ii) a DCVA backflow preventer complying with CSA 864.5.(c) Class 1 systems not covered by ltem (b), Class 2, and Class 3 fire pr,otection systems that use no

antifreeze or other additives of any kind shall be protected by(i) a DCVA backflow preventer complying with CSA 864.5; or

iiil u DCVAF backflow preventer comptying with CSA 864.5.1(d) Ciass 1, Class 2, or Class 3 fire protection systems in which antifreeze or other additives are used shall

be protectedo : by an RP backflow preventer complying with CSA 864.4 or an RPF backflow preventer

complying with CSA 864.4.1, on the portion of the fire protection system with the additives; and(ii) in accordance with ltem (b) or (c), on the balance of the fire protection system.

(e) Class 4 and Class 5 fire protection systems shall be protected by(i) an RP backflow preventer complying with CSA 864.4; or(ii) an RPF backflow preventer complying with CSA 864.4.1.

(f) Class 6 fire protection systems shall be protected by(i) a DCVA backflow prqventer complying with CSA 864.5;(ii) a DCVAF backflow preventer complying with CSA 864.5.1;(iii) an RP backflow preventer cornplying with CSA 864.4; or(iv) an RPF backflow preventer complying with CSA 864.4.1.The type of protection shall be determined by a survey of the premises and an assessment of thehazard.

(g) Where premises isolation backflow protection with an RP backflow pr€venter is required on the waterservice pipe at an industrial, commercial, or domestic service connection that is located on the same

premises as the fire service pipe in Class 3, Class 4, Class 5, and Class 6 fire protection systems,

backflow protection with an RP backflow preventer complying with CSA 864.4 or an RPF backflowpreventer complying with CSA 864.4.1 shall also be provided on the fire service connection.

- Thble 3Selection guide for backflo]:v prel:1t"T: for fire protection systerns

(See Clauses 5.4.1 and 5.5.2.)

Pipe and fittings madeof materials acceptablefor potable watersystems

Pipe and fittings made of materialsnot acceptable for potable watersystems

Type ofdevice*

Residential"partialflow

CSA Standard through" Class 1

designation systern systemClass 1, Class 2,or Class 3 system

With antifreezeor other additives;any class system

DCVA

DCVAF

DuC

DycF

RP

RPF

SCVAF

864.5

864.5.1

864.6

864.6.1

864.4

864.4.1

864.9

':--

*The 'lF'/ ot the end of the ocronym indicates that the bac6low preuenter is only for use an fire protedion systems.

luly 2007

864.10-07 @ Conadian Stondards Associotion

t.t.5Backflow preventers specified in Clause 5.5.2 shall be installed upstream of the fire department pumperconnection.

5.6 Backflow from water filI stations

5.6.1Any outlet used on a temporary or permanent basis to dispense potable water from the water distributionsystem to water-hauling equipment shall be protected against backflow caused by back siphonage or backpressure with an RP backflow preventer.

5,6.2The water fill station piping shall be installed to enable the water downstream of the final control valve toautomatically drain to atmosphere when the connectiort to the water:hauling equipment is disconnected,at the end of each fill cycle.Note: See Annex C for odditionol information on water-hauling equipment,

s6rrr rrrarla* oa*rzlnac5.7 Backflow from temporary water servicgsAny outlet used to dispense potable water from the water distribution system to supply a temporary waterservice for construction or other purposes shall be protected against bacKlow caused by back siphonageor back pressure with(a) an RP backflow preventer, where there i5 no final connection to a plumbing system;(b) a DCVA backflow preventer, where the temBorary service is connected to a plumbing system that

' would be regarded as a low or moderate hazard; or: (c) an RP backflow preventer, where the temporary service is connected to a plumbing system that

would be regarded as a high or severe hazard.

5.8 Backf,low from inigation systenrs i

5.8.L Above-ground irrigation systemsAny outlet used to dirpense potable-water from the water distribution system to supply a

non-chemical-injected, above:ground irrigation system shall be protected against backflow caused by' back siphonage with one of the following:

(a) an HCVB device located at the hoseiibb and installed downstream of the irrigation system shut-off,solenoid, or other control valves;

(b) an AVB device installed downstream of the irrigation system shut-off, solenoid, or other controlvalves, provided that(i) the irrigation system is not in continuous use for more than 12 h at any one period of time; and(ii) the distance to the critical level of the AVB device is measured relative to the highest point of the

irrigation system (see Clause 4.3.3.4); or(c) a device specified !n Clause 5.8.2.

5.8.2 In-ground irrigation systemsAny outlet usEd to dispense potable water from the water distribution system to supply an in-groundirrigation system shall be protected against backflow caused by back siphonage with the following:(a) for systems without injection of chemicals:

least 300 mm above the highest point of the irrigation system; or(ii) a DCVA backflow preventer installed upstream of the irrigation system shut-off or other control

valves; or(b) for systems with injection of chemicals, an RP backflow preventer installed upstream of the irrigation

system shut-off valves.

luly 2007

@ Conadian Standards Associotion Selection ond installotion of bockflow preventers

6 Installation of backflow preventers and vacuum breakers

611- General requirements

6.1.1 AccessibilityBackflow preventers and vacuum breakers shall be instdled in readily accessible areas to facilitateinspection, field testing, and maintenance.Note: /t is not recommended that backflow preventerS or vacuum breakers be installed in confined spoces..See Clause 6.1 1 .

6,!,2 ClearancesExcept when the device is installed within an enclosure that complies with ASSE 1060, the minimumclearances specified in Table 4, or the manufacturer's iecommendations, whichever are greater, shall be

used when installing backflow preventers or vacuum breakers.

Table 4Clearances, mrn

(See Clause 6.1.2.)

Minimum clearance

Type ofdewice

Centreline height abovethe floorMinimum Maximum*

Between thebottom of the reliefvalve and the floor

Above the In front of Behindthedevice the devicet devicef

DCVA

DCVAF

PVB

RP

RPF

SCVAF

SRPVB

750

75A

750

7.s0

750

1500

1 500

1 500

1 500

1 500

1 500

1 500

300

300

:

300

300

300

300

300

300

300

750

750

750

750

7sa

750

750

20

20

2A

20

20

20

20

*lnstollations with o greater centreline height moy be us;ed if provided with q fixed plotform.

tTo the neorest watl or obstruction.'Notes:(f ) An em.dash (---) indicates thot there is no requirement specified in this Stondard.(2) Clearonces might hove to bii increosed for backflow preventers with side-mounted test cocks or relief valves or

6.L.3 Support and restraintBackflow pr&6nters and vacuum breakers shall be adequately supported and restrained to prevent lateral

movement.'lnstallation accessories, such as pipe hanger,s, braces, saddles, stanchions, and piers, shall be

used to sL,tppol-t backflow preventers and vacuum breakers and shall be placed in a manner that will notobstruct access to the device for testing and maintenance or interfere with the operation of the relief valve(on RP bacKlow preventers).

6.7.4 BypassesBypasses aio-und backflow.preventers or vacuum breakers shall be prohibited, except where an equivalentbackflow preventer is installed on the bypass (see Clause 6.7).

fuly 2a07