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Backflow Prevention > Chapter 5, mechanisms for preventing backflow > Flashcards

Chapter 5, mechanisms for preventing backflow Flashcards

1
Q

Air gaps are usually the cheapest form of backflow prevention, true or false?

A

True

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2
Q

Where Airgas cannot be used, these these assemblies provide a physical barrier to backflow

A

Mechanical backflow preventers

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3
Q

Two methods of non-mechanical backflow prevention are:

A

Air Gaps and Barometric Loops

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4
Q

A _____ is a mechanical way to protect against backflow.

A

Device

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5
Q

This term is referred to as the entire backflow prevention unit, including the mechanism that actually prevent backflow, but also the shut off valves and test cocks

A

Assembly

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6
Q

What term refers to the backflow prevention mechanism only, it does not include the shut off valves.

A

Device

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7
Q

Approved assemblies must be shipped from the manufacturer as:

A

One complete unit

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8
Q

What foundation at the University of Southern California field test backflow assemblies?

A

The foundation for cross connection, control, and hydraulic research

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9
Q

The backflow preventer must also have shut off valves that have a:

A

Full flow characteristic

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10
Q

Potential is the essential factor. The purpose is to eliminate unnecessary reduction in pressure since backflow preventer themselves already reduced pressure… true or false

A

True

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11
Q

This term is defined as capable of withstanding shock without permanent deformation rupture.

A

Resilient seated

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12
Q

A resilient seated valve usually contains some form of soft rubber or other flexible material that can:

A

Withstand shock

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13
Q

Shut off valves that are resilient seated are usually designated with what character or characters?

A

“R” or “RS”

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14
Q

The operating stem on a ball valve type test cock must be:

A

Blowout proof

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15
Q

To be approved, a backflow preventer must be testable and repairable:

A

In-line

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16
Q

Being repairable in-line means that the backflow preventer must be

A

Stay in place

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17
Q

These are the simplest type of mechanical backflow prevention.

A

Atmospheric vacuum breakers (AVBs)

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18
Q

Atmospheric vacuum breakers can be tested in line. True or false.

A

False

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19
Q

Atmospheric vacuum breakers can be used to protect against _______ only

A

Back siphonage

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20
Q

The AVB contains a single disc float, also known as a:

A

Poppet valve

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21
Q

AVB’s are NOT approved for use where they will be subject to

A

Continuous pressure in the direction of flow

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22
Q

Shut off valves are not allowed downstream of

A

AVB’s

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23
Q

After _______ or more hours of continuous pressure, the float can become permanently stuck to the air in the port

A

12 to 14

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24
Q

What is the image a picture of?

A

An atmospheric vacuum breaker.

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25
Q

When turning the water off to an atmosphere vacuum breaker, how can it be determined if the float disk is working?

A

It can be heard as it falls

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26
Q

What is the minimum height that a vacuum breaker must be installed to the underside of its body above the highest outlet?

A

6 inches

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27
Q

Back for pool runners are required to include an air that indicates the direction of flow in order to be designated what?

A

Approved

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28
Q

The AVB must never be subject to ________ , since it relies on atmospheric pressure to function

A

Flooding

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29
Q

True or false AVB provide protection against back pressure

A

False

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30
Q

This is an atmospheric vacuum breaker that has been adapted to fit on a hose bib or sill cock

A

Hose bib vacuum breaker

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31
Q

What is the image of picture of?

A

A pressure vacuum breaker

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32
Q

The pressure vacuum breaker is an ________ instead of a device, it has to shut off valves and two tests.

A

Assembly

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33
Q

On a pressure vacuum breaker the air inlet and the check valve operate _______ each other

A

Independently

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34
Q

The AWA specification for a spring loaded, soft seated check valve is that it must be drip tight and hold______ in the direction of flow

A

1.0 PSI

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35
Q

Generally, the PVB is used for_______. For instance, it is commonly used on lawn irrigation systems

A

Isolation

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36
Q

Unlike the AVB, the PVB can be used where it will be subjected to:

A

Continuous pressure

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37
Q

True or false because the PVB can be subjected to continuous pressure, it is acceptable to have a shut off valve downstream of the assembly.

A

True

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38
Q

The PVB cannot be subjected to

A

Back pressure

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39
Q

For a PVB, the minimum height Between the bottom of the critical level and the highest point in the system.

A

12 inches

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40
Q

Lawn irrigation systems are classified as a:

A

High Hazard

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41
Q

Similar to PVB’s these type of vacuum breakers have two shut off valves, one test cock, and one bleed screw

A

Spill resistant vacuum breakers.

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42
Q

True or false the SVB does not discharge water when the assembly is pressurized

A

True

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43
Q

The critical level of a SBV is usually located at the opening of the

A

Check valve

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44
Q

The springs in a ______ are identical, and sometimes interchangeable

A

Double check valve assembly

45
Q

According to AWWA specifications, the springs inside of a double check valve assembly should hold drip tight against

A

One PSI in the normal direction of flow

46
Q

According to a WWE specifications, the springs inside of a double check valve assembly should hold drip tight against

A

One PSI in the normal direction of flow

47
Q

The maximum pressure drop out across a double check valve assembly is:

A

10 psi

48
Q

True or false double check valves do not provide adequate protection against both types of backflow: back siphonage, and back pressure

A

False

49
Q

Double check valve assemblies can be subjected to continuous pressure. Under normal flow conditions, the first check valve effectively reduces the supply line pressure by what range?

A

1.0 to 5.0 psi

50
Q

The maximum pressure loss allowed across a DC VA cannot exceeded:

A

10 psi

51
Q

Double check valve assemblies are only approved for

A

Low or non-Health hazard situations

52
Q

DCVAs are traditional used _______ and are installed after the meter or at the point of service

A

For isolation

53
Q

Double check valve assemblies should be installed at least ______ and at most _____ above the ground, drainage system, or flood elevation

A

12 inches to 36 inches

54
Q

True or false, double check valve assemblies may be installed inside of vaults

A

True

55
Q

Vault installations are considered to be:

A

Confined spaces

56
Q

These are the only approved backflow preventers that can be installed below ground. This installation is usually discouraged.

A

Double check valve assemblies

57
Q

What is this a picture of?

A

Reduced pressure principle assembly

58
Q

On an RP, the first check valve is designed to reduce water pressure by a minimum of approximately:

A

5.0 psi

59
Q

On an RP the second second check valve is only designed to hold back a minimum of:

A

1.0 psi

60
Q

Inside of a RP a _____ is created that will not allow water to backflow

A

Hydraulic gradient

61
Q

On an RP the area between the first check valve and the second check valve is referred to as what?

A

The reduced pressure zone

62
Q

When the relief valve opens to the atmosphere, it provides what between the two check valves?

A

An air gap

63
Q

The spring on an RP relief valve is designed to provide a minimum pressure of

A

2.0 psi

64
Q

Under normal operating conditions, the pressure inside the reduce pressure zone is approximately ________ less than the pressure on the supply side of the first check

A

5.0 to 12.0 PSI

65
Q

The 5.0 psi deficiency between the high side pressure and the zone pressure allows for some:

A

Fluctuation in the line pressure

66
Q

Because the relief foul provides edit protection, the RP is considered adequate for:

A

High and low hazards

67
Q

The RP is considered the most ________ backflip as it can be used in all situations except for inside of a vault

A

Versatile

68
Q

The RP should be installed so that the vent of the differential relief valve is at least ________ no more than ______ above grade

A

12 inches, 36 inches

69
Q

AARP should have a minimum clearance________ on all sides

A

24”

70
Q

If a drain line is installed on the relief port a ______ should be provided to avoid creating a cross connection between the assembly and the drain

A

Manufactured air gap

71
Q

______ is caused by air in the system or fluctuations in line pressure

A

Spitting

72
Q

If there is a loss in supply line pressure to the RP, what happens?

A

It dumps the zone

73
Q

A steady drip or continuous flow of water from the vent indicates that the RP is:

A

Not working properly

74
Q

There must be a minimum separation of two times the affected area or inside pipe diameter, of the water supply outlet between the outlet and the:

A

Flood level rim

75
Q

What is the absolute minimum that must be maintained for an airgap?

A

1 inch

76
Q

______ is the attraction of unlike particles.

A

Adhesion

77
Q

_______ is the attraction of like particles

A

Cohesion

78
Q

_______ is the attraction of like particles

A

Cohesion

79
Q

If the water supply outlet is adjacent to a sidewall, within three diameters of the water supply outlet, the minimum air gap must be

A

Three times the inside diameter of the outlet pipe

80
Q

A barometric loop of 34 feet high is effective against what form of backflow only?

A

Back siphonage

81
Q

A single check valve is not considered a:

A

Adequate form of backflow prevention

82
Q

A single check valve cannot be tested:

A

In line

83
Q

Dual in-line check valves that cannot be tested. Have a _______ failure rate for both checks within the first five years.

A

50%

84
Q

This type of check is designed to detect small weeks or illegal water usage that cannot be detected by the less sensitive meter installed on the large line upstream from this assembly

A

Detector check

85
Q

This type of check is designed to detect small weeks or illegal water usage that cannot be detected by the less sensitive meter installed on the large line upstream from this assembly

A

Detector check

86
Q

What is the image a picture of?

A

A double check detector assembly

87
Q

The maximum pressure loss through a double check detector assembly is:

A

10psi

88
Q

For a double detector check assembly the first spring must hold drip tight against

A

1.0 psi regardless of the size of assembly

89
Q

What is the maximum size of a reduced pressure detector assembly?

A

10 inches

90
Q

What is the maximum size of a reduced pressure detector assembly?

A

10 inches

91
Q

Where are reduced pressure detector assemblies frequently used?

A

Fire sprinkler systems

92
Q

If a fire sprinkler system does not have any additives and has no chance for auxiliary water supply to be connected then the system is considered

A

Low hazard

93
Q

For low hazard fire sprinkler systems what is considered the appropriate assembly?

A

A double detector check

94
Q

A detector bypass on a backflow prevention assembly is not necessary if the fire protection system has an

A

Operating alarm that will indicate if water is flowing

95
Q

Reduced pressure detector assemblies average about ________ PSI pressure loss

A

13 or 14

96
Q

Regular RPZ assemblies about _______ pressure loss

A

10 psi

97
Q

Prior to installation, the waterline should be_______ to remove loose materials that could foul the backflow preventer

A

Thoroughly flushed

98
Q

True or false sometimes it is recommended that a strainer be located prior to the assembly to trap any loose materials that could otherwise file the assembly

A

True

99
Q

True or false, providing a blow off valve after the backflow preventer is not a good idea

A

False, the blow off valve can be used to remove grease and form materials that are produced when repairing the assembly, or to flush the customers waterline of any contaminants after a backflow incident without contaminating the backflow preventer

100
Q

True or false, providing a blow off valve after the backflow preventer is not a good idea

A

False, the blow off valve can be used to remove grease and form materials that are produced when repairing the assembly, or to flush the customers waterline of any contaminants after a backflow incident without contaminating the backflow preventer

101
Q

This is the increase in pressure in a closed water system due to heating and expanding water

A

Thermal expansion

102
Q

This is the increase in pressure in a closed water system due to heating and expanding water

A

Thermal expansion

103
Q

For proper function, T and P valves need to be

A

Exercised regularly

104
Q

Well, almost backflow preventers may withstand freezing temperatures for short period of time, anytime over what can burst the assembly?

A

10 hours

105
Q

To prevent freezing, the customer should either_______ or ________

A

Enclose the assembly with a heat source, or continuously run water

106
Q

Backflow preventer should be rebuilt or replaced every?

A

Five years

107
Q

Records concerning variance or exemption granted to the system shall be kept for a period and they not less than

A

Five years following the expiration of the variance and exemption

108
Q

Any systems subject to the requirements of rule 62–550.800, F. A. C. Shall retain no fewer than how many years original records.

A

12 years

Backflow Prevention (11 decks)

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