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ASSE 6040 practice questions

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Question 1Cross-Connection Control Concepts and Terminology

Which term describes a physical or hydraulic link between a potable water supply and a source of contamination?

  1. Backsiphonage
  2. Cross-connection Correct answer.
  3. Air gap
  4. Backpressure

Explanation

A cross-connection is any actual or potential connection between a potable water system and any source of contamination or pollution. Backsiphonage and backpressure are mechanisms that can cause flow reversal through such a connection, not the connection itself.

Question 2Cross-Connection Control Concepts and Terminology

What is the difference between a pollutant and a contaminant in cross-connection control terminology?

  1. A pollutant is a gas; a contaminant is always a liquid
  2. There is no distinction; the terms are interchangeable
  3. A pollutant impairs quality but is not a health hazard; a contaminant is a health hazard Correct answer.
  4. A pollutant is always toxic; a contaminant only affects taste

Explanation

A pollutant is a substance that degrades water quality but does not create a health hazard, such as a color or odor problem. A contaminant is a substance that creates a health hazard if introduced into potable water, so it demands the highest level of protection.

Question 3Cross-Connection Control Concepts and Terminology

Backsiphonage occurs when which condition exists in the potable water supply?

  1. A closed downstream valve
  2. Excessive downstream pump pressure
  3. A thermal expansion tank failure
  4. Negative or sub-atmospheric pressure Correct answer.

Explanation

Backsiphonage results from a negative or reduced pressure in the supply piping, which draws nonpotable liquid into the potable system. Backpressure, by contrast, results from downstream pressure exceeding supply pressure.

Question 4Cross-Connection Control Concepts and Terminology

Which backflow mechanism is created by a downstream pump, boiler, or elevated tank pushing water back into the potable supply?

  1. Aspiration
  2. Induced siphonage
  3. Backpressure Correct answer.
  4. Backsiphonage

Explanation

Backpressure occurs when pressure downstream of a cross-connection exceeds the pressure in the potable supply, forcing flow in reverse. Pumps, boilers, and elevated storage are common sources of such downstream pressure.

Question 5Cross-Connection Control Concepts and Terminology

What is the minimum air gap requirement for a device serving as a backflow preventer, measured relative to the flood level rim?

  1. One times the effective opening diameter
  2. Half the effective opening diameter
  3. Four times the effective opening diameter
  4. Two times the effective opening diameter Correct answer.

Explanation

The minimum air gap is generally two times the diameter of the effective opening of the supply pipe, with a floor value for small openings. This separation ensures that a physical break prevents any backflow under normal conditions.

Question 6Cross-Connection Control Concepts and Terminology

An atmospheric vacuum breaker is designed to protect against which condition only?

  1. Both backpressure and backsiphonage
  2. Thermal expansion
  3. Backsiphonage Correct answer.
  4. Backpressure

Explanation

An atmospheric vacuum breaker protects against backsiphonage only and must not be subjected to continuous pressure. It is not approved for backpressure protection, which distinguishes it from pressure-type vacuum breakers.

Question 7Cross-Connection Control Concepts and Terminology

A reduced pressure principle backflow assembly is typically required for which application?

  1. A high-hazard connection subject to both backpressure and backsiphonage Correct answer.
  2. A low-hazard connection with only backsiphonage risk
  3. A decorative fountain with no chemicals
  4. An irrigation system with no chemical injection

Explanation

The reduced pressure principle assembly provides protection against both backpressure and backsiphonage and is used for high-hazard applications. Its design includes a relief valve that discharges if a pressure differential is lost.

Question 8Cross-Connection Control Concepts and Terminology

Which term describes the flow of water or other liquids into a potable water system from any source other than its intended source?

  1. Surcharge
  2. Backwash
  3. Backflow Correct answer.
  4. Cross-flow

Explanation

Backflow is the unwanted reverse flow of water or other substances into a potable water system from an unintended source. It can result from backsiphonage or backpressure and is the condition that backflow preventers are designed to stop.

Question 9Cross-Connection Control Concepts and Terminology

A double check valve assembly is appropriate only when which condition is true?

  1. The hazard is low and backpressure is not expected to be severe Correct answer.
  2. The hazard is high and toxic materials are present
  3. The connection is subject to continuous backpressure from a boiler
  4. The device will be installed below grade without drainage

Explanation

Double check valve assemblies are approved for low-hazard applications where only a nuisance or non-health hazard exists. They are not suitable for high-hazard or toxic connections because they lack a relief mechanism.

Question 10Cross-Connection Control Concepts and Terminology

What does the term flood level rim mean in cross-connection control?

  1. The point where a pump discharges
  2. The lowest drain connection on a fixture
  3. The edge of a receptacle from which water overflows Correct answer.
  4. The highest point of a water main

Explanation

The flood level rim is the edge of a receptacle or fixture over which water would overflow onto the floor. Air gaps are measured relative to this rim to ensure adequate separation from the supply opening.

Question 11Cross-Connection Control Concepts and Terminology

Which situation best illustrates an indirect cross-connection?

  1. A submerged inlet in a tank below the overflow rim Correct answer.
  2. A welded joint between two potable lines
  3. A direct pipe connection to a chemical tank
  4. A booster pump discharging into a main

Explanation

An indirect cross-connection occurs when a potable outlet is submerged or exposed to a contaminant without a direct physical pipe connection. A submerged inlet below the flood level rim is a classic example of this potential hazard.

Question 12Cross-Connection Control Concepts and Terminology

A hose bibb with a threaded outlet in a janitorial closet is best protected by which device?

  1. Pressure vacuum breaker
  2. Double check valve assembly
  3. Hose bibb vacuum breaker Correct answer.
  4. Reduced pressure principle assembly

Explanation

A hose bibb vacuum breaker is a small, inexpensive device installed on threaded hose outlets to prevent backsiphonage through a submerged hose. It is appropriate for this low-cost, point-of-use protection.

Question 13Cross-Connection Control Concepts and Terminology

A pressure vacuum breaker differs from an atmospheric vacuum breaker primarily because it can do what?

  1. Be installed below grade
  2. Operate under continuous pressure Correct answer.
  3. Protect against backpressure
  4. Serve high-hazard toxic connections

Explanation

A pressure vacuum breaker contains a loaded check valve and can remain under continuous supply pressure, unlike an atmospheric vacuum breaker. Both, however, protect only against backsiphonage, not backpressure.

Question 14Cross-Connection Control Concepts and Terminology

What is the purpose of the relief valve on a reduced pressure principle backflow assembly?

  1. To vent air from the assembly during startup
  2. To discharge water if the pressure differential between zones is lost Correct answer.
  3. To drain the assembly for winterization
  4. To regulate downstream pressure to a set value

Explanation

The relief valve discharges if the pressure in the first zone drops close to the second zone pressure, indicating a possible failure of the check valves. This discharge protects the potable supply by maintaining the reduced pressure zone.

Question 15Cross-Connection Control Concepts and Terminology

Which of these is an example of a direct cross-connection?

  1. A faucet with an air gap
  2. A pipe permanently connected from a boiler feed to a potable line Correct answer.
  3. A hose lying in a mop bucket
  4. A submerged irrigation head

Explanation

A direct cross-connection is a physical pipe-to-pipe connection between potable water and a nonpotable source. A permanent piping connection from a boiler feed to a potable line is a clear example of that direct linkage.

Question 16Cross-Connection Control Concepts and Terminology

A facility injects fertilizer through a chemigation system into an irrigation line. Which protection level is generally required?

  1. Double check valve assembly
  2. Reduced pressure principle assembly Correct answer.
  3. Hose bibb vacuum breaker
  4. Atmospheric vacuum breaker

Explanation

Chemigation introduces a health hazard, so the connection is treated as high hazard and requires a reduced pressure principle assembly. Devices that protect only against backsiphonage are inadequate when chemicals are injected.

Question 17Cross-Connection Control Concepts and Terminology

What does the term containment mean in a cross-connection control program?

  1. Protecting the public water system at the service connection Correct answer.
  2. Protecting each fixture within a building
  3. Testing devices annually without regard to location
  4. Isolating only the boiler feed line

Explanation

Containment is the strategy of protecting the public water supply at the point of service, typically with a single assembly at the meter. It contrasts with isolation, which protects individual fixtures or zones inside a facility.

Question 18Cross-Connection Control Concepts and Terminology

Which term refers to the plumbing arrangement that isolates a specific fixture or zone from the potable system within a building?

  1. Termination
  2. Equalization
  3. Containment
  4. Isolation Correct answer.

Explanation

Isolation protects individual fixtures, equipment, or zones inside a facility rather than the entire service. It is used in addition to containment when internal hazards warrant point-of-use protection.

Question 19Cross-Connection Control Concepts and Terminology

A backflow preventer is installed on a fire sprinkler system connection. Which concern most directly justifies this protection?

  1. The sprinkler system operates at lower pressure than the main
  2. Stagnant water and additives in the sprinkler piping can be drawn back into the potable main Correct answer.
  3. The system uses a wet-pipe design
  4. The sprinkler heads are made of plastic

Explanation

Fire sprinkler piping contains stagnant water and may contain antifreeze or other additives that could be drawn into the potable main during a pressure reversal. This health and nuisance hazard justifies a backflow preventer on the connection.

Question 20Cross-Connection Control Concepts and Terminology

What is the accepted definition of a backflow prevention device?

  1. A filter that removes contaminants from water
  2. A valve that regulates downstream pressure
  3. A meter that measures reverse flow volume
  4. An assembly or device that prevents reverse flow into a potable system Correct answer.

Explanation

A backflow prevention device is an assembly or device designed to prevent the reverse flow of water or other substances into a potable water system. Its function is protective, not pressure regulation, metering, or filtration.

Question 21Public Health Significance of Cross-Connections

What is the primary public health concern when a cross-connection allows nonpotable water to enter a drinking water system?

  1. The utility's billing meters may record inaccurate volumes
  2. Contamination may reach consumers who never see or smell a problem Correct answer.
  3. Water pressure in the building will drop noticeably
  4. Pipes may corrode faster from the added minerals

Explanation

The core public health risk is that contaminated water can travel to taps, fixtures, and users without any reliable warning sign, because many hazardous agents are colorless, odorless, and tasteless. Illness can therefore occur before anyone detects the problem.

Question 22Public Health Significance of Cross-Connections

A backflow event introduces sewage into a building's potable lines. Which outcome best represents the acute public health hazard?

  1. Reduced chlorine residual in the municipal main
  2. Increased water turbidity that improves disinfection
  3. Gastrointestinal illness from pathogens such as bacteria and viruses Correct answer.
  4. Scaling of hot water heaters from hardness minerals

Explanation

Sewage carries enteric pathogens, and ingestion of water containing them can produce gastrointestinal illness ranging from mild to severe. This direct exposure pathway is what makes sewage backflow a high-hazard situation.

Question 23Public Health Significance of Cross-Connections

Which type of cross-connection is created when a hose lies submerged in a bucket of pesticide solution while connected to a hose bibb?

  1. A direct connection capable of backsiphonage Correct answer.
  2. A closed-loop connection isolated by a check valve
  3. An indirect connection protected by an air gap
  4. A pressure-type connection that cannot backflow

Explanation

A submerged hose end forms a direct link between the potable supply and the contaminant, and a drop in supply pressure can siphon the liquid backward. This is the classic backsiphonage scenario that hose-bibb vacuum breakers are designed to prevent.

Question 24Public Health Significance of Cross-Connections

Backpressure-induced backflow is most likely to occur under which circumstance?

  1. A faucet is left open with no attached device
  2. A downstream system develops pressure higher than the supply pressure Correct answer.
  3. A water softener regenerates on its normal cycle
  4. The supply main is shut down for scheduled maintenance

Explanation

Backflow by backpressure happens when a downstream source, such as a boiler, pump, or elevated tank, creates pressure exceeding that of the potable supply, pushing nonpotable water upstream. Backsiphonage, by contrast, depends on negative or reduced supply pressure.

Question 25Public Health Significance of Cross-Connections

Why does the risk of contamination from a cross-connection increase during a water main break?

  1. Pressure losses can allow groundwater and soil to be drawn into the pipe Correct answer.
  2. Water meters reverse and add contaminants
  3. Pipe repairs always introduce treated water
  4. Chlorine levels in the main automatically double

Explanation

Main breaks produce low or negative pressure, and that loss of pressure can pull surrounding groundwater, soil, and debris into the distribution system through the break or through unprotected connections. This is why utilities issue boil-water notices after such events.

Question 26Public Health Significance of Cross-Connections

Which category of contaminant introduced by backflow is most associated with long-term, chronic health effects rather than immediate illness?

  1. Industrial solvents such as trichloroethylene Correct answer.
  2. Sewage viruses from a broken sewer line
  3. Legionella from a cooling tower
  4. Coliform bacteria from a floor drain

Explanation

Industrial chemicals like solvents can produce chronic toxicity, including organ damage and elevated cancer risk, after repeated low-level exposure. Microbial contaminants more typically cause acute illness with a shorter latency.

Question 27Public Health Significance of Cross-Connections

A facility stores a boiler treatment chemical in a tank connected to the potable makeup line without any protective device. What hazard classification does this arrangement typically represent?

  1. A low hazard suitable for a simple screen
  2. A high hazard requiring an approved reduced-pressure assembly or air gap Correct answer.
  3. A nuisance hazard correctable by flushing
  4. No hazard, because the chemical is diluted

Explanation

Toxic chemicals that could cause serious illness or death if introduced into drinking water are classed as high hazards. High hazards require protection such as a reduced-pressure principle backflow assembly or a physical air gap, which provide protection against both backpressure and backsiphonage.

Question 28Public Health Significance of Cross-Connections

Why is an unprotected connection to a fire sprinkler system treated as a public health concern even when the system is normally filled with potable water?

  1. Sprinkler systems always contain radioactive isotopes
  2. Sprinkler water is intentionally treated with sewage
  3. Sprinkler piping can stagnate and accumulate biological growth and debris over time Correct answer.
  4. Sprinkler piping is made of lead in all jurisdictions

Explanation

Fire protection piping often sits idle for long periods, allowing stagnation, corrosion products, and biofilm to develop, and some systems contain antifreeze or other additives. If backflow occurs, this degraded water can be pushed into the potable supply, which is why approved protection is required.

Question 29Public Health Significance of Cross-Connections

Which statement best explains why an air gap provides the highest level of protection against cross-connection contamination?

  1. It uses a spring-loaded check to stop reverse flow
  2. It relies on a downstream pressure gauge to detect problems
  3. It disinfects water as it passes through the device
  4. It creates a physical separation that no backflow condition can bridge Correct answer.

Explanation

An air gap is a physical, unobstructed separation between the potable outlet and the flood-level rim of the receiving vessel. Because there is no continuous connection, neither backpressure nor backsiphonage can move contaminants into the potable supply.

Question 30Public Health Significance of Cross-Connections

A hospital dialysis unit uses water that passes through a cross-connection-susceptible piping network. Why is this population especially significant from a public health standpoint?

  1. Dialysis water is never regulated
  2. Dialysis patients are immune to waterborne pathogens
  3. Dialysis machines filter out all chemical contaminants
  4. Dialysis patients receive large volumes of water directly into the bloodstream Correct answer.

Explanation

During dialysis, patients are exposed to hundreds of liters of water per session across a semipermeable membrane, so contaminants that would be trivial by drinking water standards can cause serious harm. Immunocompromised patients also face heightened risk from microbial contamination.

Question 31Public Health Significance of Cross-Connections

What is the most direct reason a cross-connection control program requires identification and survey of a facility's plumbing?

  1. To reduce the number of fixtures in the building
  2. To increase water pressure in the building
  3. To locate actual and potential connections so hazards can be ranked and protected Correct answer.
  4. To satisfy insurance paperwork requirements

Explanation

Surveys exist to find where potable water may contact nonpotable substances, so each connection can be evaluated and given appropriate protection. Without identification, hazards remain unknown and unprotected.

Question 32Public Health Significance of Cross-Connections

Which situation illustrates an indirect cross-connection rather than a direct one?

  1. A hose connected to a boiler drain under pressure
  2. A pipe permanently welded to a chemical tank
  3. A pump discharge piped into a potable main
  4. A submerged inlet in a tank with a physical air gap above the flood level Correct answer.

Explanation

An indirect connection exists where potable water can reach a contaminant only through an intervening air space, as when an outlet discharges above a tank's flood-level rim. Direct connections are continuous piping links with no air space.

Question 33Public Health Significance of Cross-Connections

A community experiences an outbreak of illness traced to a building's unprotected auxiliary water supply. Which principle does this most clearly demonstrate?

  1. Cross-connection hazards are confined to industrial facilities
  2. Auxiliary supplies always improve water quality
  3. Backflow only affects the building where it starts
  4. Contamination introduced at one point can affect an entire distribution network Correct answer.

Explanation

Once contaminated water enters the distribution system, pressure gradients can carry it to other buildings and users far from the original site. This is why cross-connection control is a community-wide public health responsibility rather than a private plumbing matter.

Question 34Public Health Significance of Cross-Connections

Which factor most strongly determines the severity of a potential backflow incident at a given connection?

  1. The diameter of the potable service line
  2. The color of the piping in the mechanical room
  3. The age of the water meter
  4. The toxicity and concentration of the contaminant plus the exposure pathway Correct answer.

Explanation

Severity depends on what the contaminant is, how much could enter, and whether people could ingest or contact it. A highly toxic substance in a direct connection presents far greater risk than a benign one, regardless of pipe size or hardware age.

Question 35Public Health Significance of Cross-Connections

Why do public health agencies treat cross-connection control as a preventive measure rather than a response measure?

  1. Because response measures are illegal
  2. Because contamination is often undetectable until illness occurs, prevention avoids exposure entirely Correct answer.
  3. Because backflow events are always visible
  4. Because treatment plants cannot disinfect water

Explanation

Many contaminants produce no taste, odor, or color, so detection typically comes only after people become ill. Preventing the connection from forming, or isolating it with approved devices, stops exposure before it can occur.

Question 36Public Health Significance of Cross-Connections

A lawn irrigation system draws from a pond and is also connected to the municipal supply. What is the primary public health concern?

  1. The irrigation timer may fail
  2. The pond may overflow onto the lawn
  3. The pond may attract insects
  4. Pond water and its organisms could be drawn into the municipal main Correct answer.

Explanation

A dual supply creates a direct pathway between a nonpotable source and the public water system, and pressure fluctuations can drive pond water into the main. Irrigation connections are a recognized cause of community contamination events.

Question 37Public Health Significance of Cross-Connections

Which scenario best demonstrates how a seemingly minor cross-connection can cause a widespread public health event?

  1. A water heater's anode rod corrodes
  2. A submerged hose at a car wash fills the service main with soapy water during a pressure loss Correct answer.
  3. A faucet aerator becomes clogged with scale
  4. A single home's toilet valve fails internally

Explanation

During a pressure loss, a submerged hose can siphon a large volume of contaminated water into the main, and that water can then travel to neighboring properties. Small, ordinary connections are therefore capable of producing community-scale exposure.

Question 38Public Health Significance of Cross-Connections

Which of the following best describes the relationship between cross-connection control and waterborne disease surveillance?

  1. Surveillance replaces the need for backflow protection
  2. Surveillance identifies outbreaks that may reveal previously unrecognized cross-connections Correct answer.
  3. Surveillance is only used for wastewater treatment
  4. Surveillance measures pipe pressure

Explanation

Disease surveillance can detect clusters of illness that point back to a contamination event, prompting investigation of the plumbing and connections involved. Findings from such investigations often lead to improved protection requirements.

Question 39Public Health Significance of Cross-Connections

What is the significance of the flood-level rim in evaluating a cross-connection?

  1. It shows where the meter is installed
  2. It indicates the pipe's pressure rating
  3. It determines the color coding of the pipe
  4. It marks the highest level water can reach before overflowing, defining the minimum air gap Correct answer.

Explanation

The flood-level rim is the level at which water would overflow the receiving vessel. An air gap must be maintained above that level so that a rise in water level or a wave cannot bridge the separation and restore contact with the potable outlet.

Question 40Public Health Significance of Cross-Connections

Why are cross-connections in health care and food processing facilities subject to especially strict control?

  1. Their operations combine high-hazard substances with vulnerable or large exposed populations Correct answer.
  2. Their water is supplied only by tanker trucks
  3. These facilities use no water
  4. These facilities are exempt from plumbing codes

Explanation

Health care and food processing bring together potentially hazardous materials, complex piping, and people who may be ill or otherwise susceptible. The combination raises both the likelihood and the consequence of a contamination event, justifying stricter protection.

Question 41Backflow Prevention Assemblies and Devices

Which condition is the primary reason a reduced pressure principle backflow prevention assembly is used instead of a double check valve assembly?

  1. The system needs protection only against low-hazard pollutants under continuous pressure
  2. The system requires protection against both backpressure and backsiphonage of hazardous contaminants Correct answer.
  3. The system requires an assembly that can be installed below grade in a vault
  4. The system operates at pressures that exceed the rating of check valve assemblies

Explanation

A reduced pressure principle assembly provides the highest level of mechanical protection because it discharges to atmosphere when a pressure differential reverses, protecting against both backpressure and backsiphonage of hazardous materials. A double check valve assembly lacks a relief port and is limited to non-health-hazard applications.

Question 42Backflow Prevention Assemblies and Devices

A reduced pressure principle backflow prevention assembly must be installed at what minimum height above the surrounding ground or floor?

  1. Eighteen inches
  2. Six inches
  3. Twenty-four inches
  4. Twelve inches Correct answer.

Explanation

The relief valve of a reduced pressure principle assembly must be at least 12 inches above the surrounding grade or floor to allow visible discharge and prevent flooding or contamination of the relief port. This clearance also keeps the relief valve above flood level.

Question 43Backflow Prevention Assemblies and Devices

What is the correct term for the unobstructed vertical distance through free atmosphere between a water outlet and the flood level rim of the receiving vessel?

  1. Vacuum breaker
  2. Air gap Correct answer.
  3. Relief valve clearance
  4. Barometric loop

Explanation

An air gap is the physical separation between the lowest point of a water supply outlet and the flood level rim of the fixture or vessel it serves. It is the only backflow protection method that is not a mechanical device and provides the highest degree of protection.

Question 44Backflow Prevention Assemblies and Devices

Which device is designed to prevent backsiphonage only and is not intended to protect against backpressure?

  1. Dual check valve assembly
  2. Pressure vacuum breaker assembly Correct answer.
  3. Double check valve assembly
  4. Reduced pressure principle assembly

Explanation

A pressure vacuum breaker assembly protects against backsiphonage by admitting air into the system when pressure drops, but it cannot prevent backflow caused by downstream backpressure. It must be installed above the highest downstream outlet.

Question 45Backflow Prevention Assemblies and Devices

A backflow prevention assembly tester records a differential pressure reading across the first check of a reduced pressure principle assembly. What does this reading primarily indicate?

  1. The relief valve opening pressure
  2. The pressure loss through the second check valve
  3. The static supply pressure upstream of the assembly
  4. The pressure drop across the first check valve under flow conditions Correct answer.

Explanation

The differential across the first check reflects the pressure drop created by that check valve while water flows through it. Testers compare this value to the manufacturer minimum to confirm the check is seating and functioning.

Question 46Backflow Prevention Assemblies and Devices

Which of the following best describes backpressure as a cause of backflow?

  1. A break in a main lowers pressure and pulls water from a cross connection
  2. A pump draws water from a tank into the distribution system
  3. Supply pressure drops below atmospheric and creates a siphon
  4. Downstream pressure exceeds supply pressure and pushes water backward through the piping Correct answer.

Explanation

Backpressure occurs when pressure downstream of an assembly or connection rises above the supply pressure, forcing water to flow in the reverse direction. Common causes include boilers, elevated tanks, and pumps.

Question 47Backflow Prevention Assemblies and Devices

What is the minimum number of test cocks required on a reduced pressure principle backflow prevention assembly?

  1. Three
  2. Four Correct answer.
  3. Two
  4. Five

Explanation

A reduced pressure principle assembly requires four test cocks to allow testing of the two check valves and the relief valve differential. These ports permit the tester to measure pressures at each critical point.

Question 48Backflow Prevention Assemblies and Devices

Which term describes a connection between a potable water system and a nonpotable system that could allow contamination to enter the potable supply?

  1. Bypass line
  2. Cross connection Correct answer.
  3. Service connection
  4. Air gap

Explanation

A cross connection is any actual or potential link between a potable water system and a source of contamination or pollution. Controlling cross connections is the central purpose of backflow prevention programs.

Question 49Backflow Prevention Assemblies and Devices

A tester is performing a check valve test on a double check valve assembly and finds the first check holds at 1.0 psi differential. How should this result be interpreted?

  1. The first check passes because any positive differential is acceptable
  2. The assembly must be replaced entirely without further testing
  3. The second check must be tested first before any judgment is made
  4. The first check fails because it is below the typical minimum differential Correct answer.

Explanation

Double check valve assemblies are typically required to hold a minimum differential, commonly 1.0 psi or greater depending on the standard, and a reading at or below the threshold indicates the check is not seating properly. The tester should follow the applicable standard and manufacturer criteria before declaring failure.

Question 50Backflow Prevention Assemblies and Devices

Why must a pressure vacuum breaker assembly be installed above the highest downstream outlet it protects?

  1. To allow the assembly to drain automatically after each use
  2. To keep the assembly within the rated temperature range
  3. To ensure the air inlet opens to atmosphere during a backsiphonage event Correct answer.
  4. To prevent backpressure from damaging the internal poppet

Explanation

A pressure vacuum breaker relies on its air inlet opening to atmosphere when supply pressure drops, which breaks the siphon. If installed below a downstream outlet, water can remain in the piping and the device cannot provide the required protection.