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Cross Connections > Chapter 4 - Backflow preventers > Flashcards

Chapter 4 - Backflow preventers Flashcards

1
Q

What is the definition of an air gap?

A

Is the unobstructed vertical distance through air bn the lowest pt of a water supply / flood level rim of fixture or vessel

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2
Q

What are the measurements of an air gap?

A

2x pipe diameter
min 1 “

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3
Q

What are the 3 downsides to the use of an air gap?

A

1) Does not guarantee continuous protection
2) Not always practical
3) easily bypassed

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4
Q

Are approved air gaps required to be included in a yearly testing program?

A

Yes

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5
Q

Are air gaps usually accompanied by the installation of an RP for area isolation?

A

Yes

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6
Q

The reduced pressure principle backflow prevention assembly (RP) consists of what?

A
  • 2 indy acting internally loaded CV
  • Reduced pressure zone
  • Pressure diff relief value
  • 2 - shut off valves
  • 4 test cocks
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7
Q

What does the “D” stand for in RPD?

A

Detector

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8
Q

What is the difference bn RP and RPD?

A

RPD has everything a RP has, plus additional RP / water meter in a bypass configuration

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9
Q

What are the hazards / hydraulics that an RP / RPD protects against?

A

Hazards: Minor, Moderate, Severe
Hydraulics: Con’t pressure, Back pressure, Back siphonage

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10
Q

To what position are the CV / RV internally loaded? (RP)

A

CV = closed
RV = open

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11
Q

What stops what from dripping constantly from the relief port during static / flow conditions?

A

Flow conditions = Supply pressure acting on a diaphragm w/in the RV
Static = closed CV + supply pressure

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12
Q

Why should adequate clearance to ceilings and walls be provided around an RP?

A
  • for testing purposes
  • Facilitate removal of PRV + CV
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13
Q

Why should an RP not be installed in a pit below ground?

A

Creates a cross connection if the atmospheric vent is submerged in ground water

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14
Q

What is the exception of putting an RP below ground?

A

Semi - recessed pit w/ bore sighted daylight drain

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15
Q

What precautions should be observed when an RP is located w/in a building?

A

Provide drainage to receive spillage from RV port

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16
Q

When is a strainer not recommended to be installed upstream of an RP?

A

on a fire line backflow preventer
- Needs approval from AHJ or insurance underwriters

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17
Q

True or False: RPs are normally installed horizontally.

A

True

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18
Q

What can be installed upstream of an RP if the supply pressure is subjected to pressure fluctuations which result in periodic spilling from the relief port?

A

Soft seated check valve

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19
Q

a DCVA / DCDA consists of?

A
  • 2 indy acting, internally loaded CV
  • 2 tightly closed shut off valves
  • 4 test cocks
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20
Q

What is the difference bn a DCVA and a DCDA?

A

Consists of everything a DCVA has plus another DCVA + water meter –> detects any leakage or unauthorized usage of water

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21
Q

What are the hazards / hydraulics that a DCVA / DCDA protect against?

A

Hazards: minor, moderate, severe
Hydraulics: con’t pressure, back pressure, back siphonage

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22
Q

When can a DCVA be installed on a pit below ground?

A

When the pit can be provided w/ adequate drainage to maintain a dry pit
- test cocks have to have water tight coverage / plugged

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23
Q

What must be done to a DCVA if it is installed in an area prone to flooding?

A
24
Q

A pressure vacuum breaker assembly (PVB) consists of?

A
  • internally loaded CV
  • internally loaded vacuum RV for the downstream side
  • Inlet / Outlet shut off valve
  • 2 test cocks
25
Q

To what position are the CV and vacuum RV internally loaded?

A

CV - closed
RV - open

26
Q

How does a spill resistance pressure vacuum breaker (SRPVB) differ from a PVB?

A

SRPVB has an additional internal spill - resistant membrane

27
Q

What are the Hazards and Hydraulics that a PVB will protect against?

A

Hazards: minor, moderate, severe
Hydraulics: con’t pressure, back siphonage

28
Q

A PVB must be installed a min of (what) inches above the highest downstream piping?

A

12” (300mm)

29
Q

What is an option if occasional spitting from a PVB is objectionable?

A

Installing a SRPVB

30
Q

What does an AVB consist of?

A
  • Valve body containing a Vacuum RV (aka poppet)
  • Vacuum RV seat
  • CV seat
  • Atmospheric vent
31
Q

What are the Hazards and Hydraulics that an AVB will protect against?

A

Hazards: minor, moderate, severe
Hydraulics: back siphonage

32
Q

What is the max duration that an AVB may be subjected to a con’t pressure?

A

less than 12 hours

33
Q

True or False: a shutoff valve used in conjunction w/ an AVB may be located upstream from the AVB.

A

True

34
Q

How high above the highest downstream piping must an AVB be installed?

A

1” (25mm)
Manufacturer’s recommendation = 6” (150mm)

35
Q

May an AVB be installed in a horizontal orientation?

A

No, vertically - needs to be in a visible location for maintenance

36
Q

What does a hose connection vacuum breaker (HCVB) consist of?

A
  • CV force loaded to a normally closed position
  • atmospheric vent
37
Q

What does a hose connection dual check type vacuum breaker (HCDVB) consist of?

A

Everything a HCVB has plus a second (downstream) CV

38
Q

What type(s) of backflow and hazards is the HCVB effective to protect against?

A

Hazards: minor, moderate (when paired with DCVA, RP or AG), Severe (when paired w/ RP or AG)
Hydraulics: back siphonage

39
Q

A HCDVB will protect against back siphonage and low head back pressure dt the terminal end of the hose being at an elevation equal to or less than?

A

3m (10’)

40
Q

What class of hazard is the HCDVB effective to protect against?

A

Minor

41
Q

What kind of outlets are HCVB / HCDVB installed on?

A

Hose threaded outlets
ex: hose bibs, service sinks + wall hydrants

42
Q

Can a HCVB be subjected to a con’t pressure?

A

No

43
Q

What does a lab faucet vacuum breaker (LFVB) consist of?

A
  • 2 indy acting CVs - normally closed position
  • auto venting to atmosphere
  • vacuum breaker
44
Q

A LFVB shall be located on which side of the last control valve?

A

Discharge side

45
Q

What does a dual check w/ atmospheric port (DCAP) consist of?

A
  • 2 indy acting, internally loaded normally closed CV
  • Normally closed atmospheric port
46
Q

True or False: The DCAP is designed for use under con’t pressure

A

True

47
Q

Is a DCAP allowed to be used as a replacement for an RP?

A

No - Does not protect against moderate or severe hazards

48
Q

What does a dual check valve backflow preventer (DuC / DuCF) consist of?

A
  • 2 indy acting CV force loaded to normally closed position
  • normally closed atmospheric port
49
Q

What is the outcome if a carbon dioxide or carbonated water were to backflow into copper piping?

A

Can leach metals into drinking water supply
Causes copper poisoning

50
Q

The piping or fittings downstream of a DCAPC (Dual check w/ atmospheric port for carbonated water) shall not be made of?

A

Copper or copper alloy material

51
Q

True or False: the DuC/DuCF has at atmospheric port.

A

True

52
Q

What does a single check valve assembly for fire systems (SCVAF) consist of?

A
  • 1 internally loaded CV
  • 2 tightly closing, resilient seated, shutoff valves
  • Test cocks
53
Q

What does a barometric loop consist of?

A

pipe arrangement that uses the principle that a perfect vacuum can only lift water 10m (34’) at atmospheric pressure

54
Q

What do the initials IAPMO stand for?

A

International Association of Plumbing + mechanical Officials

55
Q

Name 6 types of water - using equipment which have built in backflow preventers

A

1) clothes washing machines + dishwashers
2) Toilet or Urinals
3) Chemical or detergent dispensers
4) Beverage machines + dispensers
5) Ice Machines
6) Double wall heat exchangers w/ a visible means of leak detection

Cross Connections (10 decks)

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