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Backflow Tester practice questions

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Question 1Cross-connection control and backflow prevention

Which term describes a physical link between a potable water supply and a nonpotable source through which backflow can occur?

  1. Vacuum breaker
  2. Cross-connection Correct answer.
  3. Pressure zone
  4. Air gap

Explanation

A cross-connection is any actual or potential physical connection between a potable water system and any source of nonpotable fluid or contamination. The presence of such a link is what makes backflow a hazard, so identifying and eliminating cross-connections is the core purpose of a cross-connection control program. Devices and assemblies are installed to protect these points.

Question 2Cross-connection control and backflow prevention

Backflow that occurs when a supply main loses pressure and the downstream pressure becomes higher than the supply pressure is called:

  1. Cavitation
  2. Water hammer
  3. Backsiphonage
  4. Backpressure Correct answer.

Explanation

Backpressure backflow happens when the pressure on the downstream side of a connection exceeds the pressure in the potable supply, pushing nonpotable water into the system. It is typically caused by pumps, boilers, or elevated tanks on the customer side. Backsiphonage, by contrast, results from a negative or reduced supply pressure.

Question 3Cross-connection control and backflow prevention

What is the minimum required air gap for an effective air gap installation serving a potable water outlet?

  1. One-half the diameter of the supply pipe
  2. Twice the effective opening of the outlet Correct answer.
  3. Equal to the diameter of the drain line
  4. One inch regardless of opening size

Explanation

An air gap must provide at least twice the effective opening of the water supply outlet, and never less than one inch, measured above the flood level rim of the receiving vessel. This separation ensures that a backflow path cannot form even under flooding conditions. The correct dimensioning depends on the effective opening, not the drain pipe size.

Question 4Cross-connection control and backflow prevention

A backflow prevention assembly installed on a service line must be tested by:

  1. A certified backflow tester recognized by the authority having jurisdiction Correct answer.
  2. Any employee of the water utility
  3. The building owner after reading the manual
  4. A licensed plumber without backflow certification

Explanation

Assemblies must be tested by certified backflow prevention assembly testers who are recognized by the authority having jurisdiction. Certification demonstrates competence in using the required test equipment and procedures. Testing by uncertified personnel generally is not accepted for compliance.

Question 5Cross-connection control and backflow prevention

Which hazard classification applies to a cross-connection that could introduce a contaminant capable of causing serious illness or death?

  1. High hazard Correct answer.
  2. Low hazard
  3. Non-hazard
  4. Aesthetic hazard

Explanation

High hazard describes any condition where a contaminant could create an imminent and substantial danger to public health, such as sewage or toxic chemicals. Low hazard involves only a pollutant that would degrade quality without posing a health threat. The classification determines the minimum type of protection required.

Question 6Cross-connection control and backflow prevention

The reduced pressure principle assembly is classified as which type of backflow preventer?

  1. Atmospheric device
  2. Dual-check device
  3. Testable assembly Correct answer.
  4. Non-testable device

Explanation

The reduced pressure principle assembly is a testable assembly with two independently acting check valves and a pressure differential relief valve. Its design provides protection against both backpressure and backsiphonage. Because it is testable, periodic verification of each component is required.

Question 7Cross-connection control and backflow prevention

Which condition is the primary cause of backsiphonage in a distribution system?

  1. Elevated downstream pressure from a booster pump
  2. Oversized water meter
  3. Excessive chlorine residual
  4. Negative or sub-atmospheric pressure in the supply line Correct answer.

Explanation

Backsiphonage occurs when pressure in the potable supply drops below atmospheric, creating a siphon that draws nonpotable liquid into the piping. Main breaks, high-flow firefighting demand, and nearby line shutdowns commonly produce this condition. Elevated downstream pressure instead produces backpressure.

Question 8Cross-connection control and backflow prevention

A hose bibb vacuum breaker is intended to protect against which condition?

  1. Thermal expansion in a closed loop
  2. Backsiphonage at a threaded outlet Correct answer.
  3. Backpressure from a boiler
  4. Continuous downstream pressure

Explanation

Hose bibb vacuum breakers are non-testable devices that prevent backsiphonage at threaded hose outlets by admitting air when supply pressure drops. They do not protect against backpressure. They are commonly required on sill cocks and similar outlets.

Question 9Cross-connection control and backflow prevention

During a field test of a reduced pressure principle assembly, the relief valve opens at a differential pressure that is:

  1. Lower than the first check valve opening point Correct answer.
  2. Independent of the check valve values
  3. Higher than the first check valve opening point
  4. Equal to the supply line pressure

Explanation

The relief valve must open at a pressure differential lower than the first check valve's opening point so the zone between checks is relieved before contaminated water can pass the first check. This relationship is the basis for verifying proper operation during testing. A relief valve opening too high indicates a failing assembly.

Question 10Cross-connection control and backflow prevention

A double check valve assembly is generally acceptable for which situation?

  1. Protection against a high-hazard sewage connection
  2. Protection of a carbonated beverage dispenser directly connected to a potable line
  3. Service where continuous relief is required
  4. Protection of a low-hazard cross-connection Correct answer.

Explanation

Double check valve assemblies are permitted only for low-hazard applications where the contaminant is a pollutant rather than a health hazard. They are not approved for high-hazard connections because they lack a relief valve and cannot discharge to atmosphere. High-hazard situations require an air gap or reduced pressure principle assembly.

Question 11Cross-connection control and backflow prevention

When testing a pressure vacuum breaker, the critical measurement is the:

  1. Temperature of the water
  2. Downstream flow rate
  3. Air inlet opening point of the check valve Correct answer.
  4. Static line pressure at the inlet

Explanation

Pressure vacuum breaker testing verifies that the air inlet opens at the specified vacuum and that the check valve holds against backpressure. The opening point of the air inlet is the key value compared with the manufacturer's specification. Flow rate and temperature are not the pass/fail criteria for this test.

Question 12Cross-connection control and backflow prevention

A facility installs a reduced pressure principle assembly in a pit below grade. Which concern most directly affects compliance?

  1. The assembly may be exposed to flooding and submerged discharge Correct answer.
  2. The pit reduces the number of test cocks needed
  3. The assembly will require no future testing
  4. The pit increases the flow velocity

Explanation

Reduced pressure principle assemblies must not be installed where the relief valve discharge can be submerged, because flooding can compromise the relief function and create a health hazard. Installation in a drainable, non-flooding location is required. Burial or flooding risk is a common cause of noncompliance.

Question 13Cross-connection control and backflow prevention

An unprotected direct connection between a potable line and a chemical feed tank is best corrected first by:

  1. Increasing the supply pressure
  2. Installing a strainer upstream
  3. Creating a physical air gap or approved RP assembly Correct answer.
  4. Adding a check valve at the tank inlet

Explanation

The preferred correction for a high-hazard chemical connection is elimination of the cross-connection through an air gap, or use of an approved reduced pressure principle assembly where an air gap is impractical. A simple check valve is inadequate for health hazards. Physical separation removes the risk entirely.

Question 14Cross-connection control and backflow prevention

The term "pollutant" in cross-connection control refers to a substance that:

  1. Degrades water quality without posing a health hazard Correct answer.
  2. Causes serious illness or death
  3. Is always radioactive
  4. Only affects pipe color

Explanation

A pollutant degrades the aesthetic or quality characteristics of water, such as taste, odor, or appearance, without creating a health hazard. A contaminant, by contrast, can cause illness or death. This distinction drives the high-hazard versus low-hazard classification.

Question 15Cross-connection control and backflow prevention

A test on a double check valve assembly shows the second check holds at a lower differential than the manufacturer's minimum. What is the appropriate action?

  1. Record it as failing and require repair or replacement Correct answer.
  2. Certify the assembly as passing
  3. Ignore the second check and test only the first
  4. Reduce the supply pressure and retest

Explanation

Each check valve must meet the manufacturer's specified minimum holding differential to pass. A second check that fails to hold indicates a defect requiring repair or replacement, followed by retesting. Certifying a failed assembly would leave the system improperly protected.

Question 16Cross-connection control and backflow prevention

Which practice best prevents backsiphonage at a janitorial sink used to fill buckets and mix chemicals?

  1. Removing the aerator
  2. Leaving a hose submerged in the bucket
  3. Using a hose bibb vacuum breaker or an air gap Correct answer.
  4. Increasing the faucet flow rate

Explanation

A hose bibb vacuum breaker or an air gap prevents a submerged hose from siphoning chemicals into the potable line when pressure drops. Keeping the hose end above the flood level rim is also essential. Submerging the hose without protection creates a direct cross-connection.

Question 17Cross-connection control and backflow prevention

A thermal expansion condition in a closed potable system can create which backflow concern?

  1. Backsiphonage from the public main
  2. Loss of chlorine residual
  3. Increased air gap size
  4. Backpressure into the supply Correct answer.

Explanation

Heated water expanding in a closed system can raise pressure above the supply pressure, producing backpressure that may push water back through a connection. Thermal expansion control, such as an expansion tank, helps manage this. Backsiphonage instead requires a pressure drop in the supply.

Question 18Cross-connection control and backflow prevention

Which assembly provides the highest level of mechanical protection against both backpressure and backsiphonage?

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

Explanation

The reduced pressure principle assembly protects against both backpressure and backsiphonage and is approved for high-hazard applications. It uses two check valves plus a differential relief valve that discharges if either check fails. Other listed devices offer narrower protection.

Question 19Cross-connection control and backflow prevention

A tester records results on a form that must be submitted to the water purveyor. Which element is essential for the record to be valid?

  1. The tester's certification number and signature Correct answer.
  2. The name of the pipe supplier
  3. The color of the assembly
  4. The building's square footage

Explanation

Test reports must identify the certified tester, include the certification number and signature, and record the assembly details and measured values. This documentation establishes accountability and allows the purveyor to verify compliance. Irrelevant building details do not validate a report.

Question 20Cross-connection control and backflow prevention

An irrigation system is directly connected to a potable supply with no protection. Which risk is most significant?

  1. Faster valve wear
  2. Fertilizer and pesticide chemicals siphoning into the main Correct answer.
  3. Increased water bills
  4. Reduced irrigation coverage

Explanation

Irrigation systems commonly inject fertilizers and pesticides and can be exposed to soil and standing water, creating a high-hazard cross-connection. A pressure loss can siphon these materials into the potable supply. Approved protection such as an RP assembly or air gap is required.

Question 21Cross-connection control and backflow prevention

When a reduced pressure principle assembly discharges water continuously from the relief valve, the most likely cause is:

  1. Normal operation during low demand
  2. A fouled first check valve or debris on the relief seat Correct answer.
  3. A properly functioning air gap
  4. Too few test cocks

Explanation

Continuous relief discharge usually indicates a fouled or failing first check valve, debris on the relief valve seat, or a lost pressure differential. The assembly requires inspection and repair by qualified personnel. Continuous discharge is not normal operation and signals a defect.

Question 22Cross-connection control and backflow prevention

Two cross-connections exist at a site: a low-hazard connection to a heating loop and a high-hazard connection to a laboratory drain. How should protection be prioritized?

  1. Take no action because heating loops are closed
  2. Protect only the low-hazard connection
  3. Protect both equally with dual check valves
  4. Protect the high-hazard connection with an air gap or RP assembly and the low-hazard connection with an appropriate device Correct answer.

Explanation

Protection must match the degree of hazard: high-hazard connections require an air gap or reduced pressure principle assembly, while low-hazard connections may use devices such as a double check assembly. Prioritizing the high hazard first addresses the greatest public health risk. Uniform low-level protection would be inadequate for the drain connection.

Question 23Cross-connection control and backflow prevention

A tester finds that a pressure vacuum breaker has been installed with the air inlet under continuous pressure from a downstream booster pump. What is the correct conclusion?

  1. The installation is acceptable because the check valve holds
  2. The installation is acceptable if tested annually
  3. The installation is improper because the device cannot be subjected to continuous pressure Correct answer.
  4. The installation is acceptable if the pump is small

Explanation

Pressure vacuum breakers are designed so the air inlet is not under continuous pressure, and a downstream booster pump violates that condition. Continuous pressure can prevent the air inlet from opening and defeats the device's protection. The installation must be corrected, typically by relocating the device or changing the arrangement.

Question 24Cross-connection control and backflow prevention

A water purveyor requires containment protection at the meter for a facility with internal high-hazard processes. What does containment protection accomplish?

  1. It prevents backflow from the facility's system into the public main Correct answer.
  2. It eliminates the need for any internal isolation
  3. It guarantees the facility's internal piping is contamination-free
  4. It protects each individual fixture inside the building

Explanation

Containment protection isolates the entire facility from the public distribution system, preventing facility-wide contamination from entering the main. It does not protect occupants from internal cross-connections, which require separate isolation protection. Both containment and isolation may be required depending on the program.

Question 25Cross-connection control and backflow prevention

During a field test, a tester cannot achieve the required pressure differential on a reduced pressure principle assembly even after confirming the test kit is calibrated. Which factor should be investigated first?

  1. The length of the discharge pipe
  2. Supply pressure fluctuations or a fouled check valve Correct answer.
  3. The building's occupancy type
  4. The color of the test cocks

Explanation

If the test kit is known good, the next likely causes are inadequate or fluctuating supply pressure or a fouled or defective check valve preventing the required differential. These directly affect the measured values during testing. Investigating the assembly and supply conditions is the logical next step.

Question 26Cross-connection control and backflow prevention

Which term describes a physical or actual connection between a potable water system and a source of possible contamination?

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

Explanation

A cross-connection is any actual or potential link between a potable supply and a nonpotable source, whether direct piping or an indirect path such as a submerged inlet. The other terms describe protection devices, flow conditions, or hydraulic events rather than the connection itself.

Question 27Cross-connection control and backflow prevention

Which condition describes backflow caused when supply pressure drops below the pressure at the customer's system, drawing nonpotable water into the main?

  1. Cavitation
  2. Backpressure
  3. Water hammer
  4. Backsiphonage Correct answer.

Explanation

Backsiphonage occurs when the potable supply pressure falls below atmospheric or system pressure, so a partial vacuum pulls nonpotable water through a cross-connection. Backpressure is the opposite situation, where downstream pressure exceeds supply pressure and pushes water backward.

Question 28Cross-connection control and backflow prevention

An atmospheric vacuum breaker relies on which feature to interrupt a cross-connection?

  1. A relief valve that discharges to a drain
  2. Two independently acting check valves
  3. A spring-loaded check element
  4. A vented air inlet that opens when flow stops Correct answer.

Explanation

An atmospheric vacuum breaker has a float or disc that seals the air inlet during flow and drops open when flow stops, admitting air to break the vacuum. This device cannot be subjected to continuous pressure, because the air inlet must be free to open.

Question 29Cross-connection control and backflow prevention

What is the minimum required air gap for a receiving vessel with a two-inch-diameter inlet opening, measured vertically from the inlet?

  1. Four inches
  2. One inch
  3. Six inches
  4. Two inches Correct answer.

Explanation

The standard minimum air gap for an effective opening is twice the diameter of the inlet, with a floor of one inch. For a two-inch inlet, twice the diameter equals four inches, so four inches is required.

Question 30Cross-connection control and backflow prevention

Which device is designed to protect against both backpressure and backsiphonage and discharges to atmosphere when it fails?

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

Explanation

A reduced pressure principle assembly contains two check valves and a differential relief valve that opens to atmosphere when conditions could allow backflow. It is the highest-rated mechanical device for combined backpressure and backsiphonage protection.

Question 31Cross-connection control and backflow prevention

Which term describes a substance that, if introduced into potable water, would create a health hazard?

  1. Contaminant Correct answer.
  2. Turbidity
  3. Additive
  4. Pollutant

Explanation

In cross-connection control, a contaminant is a substance that could cause a health hazard, such as toxic chemicals or sewage. A pollutant is a substance that degrades water quality or aesthetics but does not by itself create a health hazard.

Question 32Cross-connection control and backflow prevention

Which situation most clearly requires a reduced pressure principle assembly rather than a double check valve assembly?

  1. A laboratory sink with a faucet-mounted vacuum breaker
  2. A fire sprinkler loop supplied from the potable main
  3. A boiler feed line with chemical treatment under pressure Correct answer.
  4. A residential irrigation zone with a pressure vacuum breaker

Explanation

A chemical-treated boiler feed line can create backpressure with a health-hazard substance, which requires the higher protection of a reduced pressure principle assembly. Double check assemblies are limited to non-health-hazard situations where backpressure and backsiphonage are both possible but not hazardous.

Question 33Cross-connection control and backflow prevention

Which practice best protects a potable supply at a janitorial sink used to fill buckets and mix chemicals?

  1. Using a hose bibb vacuum breaker and keeping the hose end above the flood level Correct answer.
  2. Increasing supply pressure at the sink
  3. Filling buckets only when the building is unoccupied
  4. Leaving the hose submerged in the bucket

Explanation

A hose bibb vacuum breaker prevents backsiphonage at the outlet, and keeping the hose end above the bucket rim prevents the hose from becoming a submerged cross-connection. Both measures together address the hazard at the point of use.

Question 34Cross-connection control and backflow prevention

During a field test of a reduced pressure principle assembly, the relief valve opens at a differential pressure well below the manufacturer's minimum. What does this most likely indicate?

  1. The first check is fouled or the relief valve spring is weak Correct answer.
  2. The supply pressure is too high
  3. The assembly is installed correctly
  4. The second check is stuck open

Explanation

A relief valve that opens too easily suggests a weak relief spring or a fouled first check that reduces the differential across the valve. Either condition allows the relief valve to discharge at a lower differential than required.

Question 35Cross-connection control and backflow prevention

A pressure vacuum breaker is installed where the air inlet can be subjected to continuous pressure from downstream. What is the primary consequence?

  1. The air inlet may fail to open, defeating backsiphonage protection Correct answer.
  2. The check element will last longer
  3. The device will act as an air gap
  4. The device will provide better backpressure protection

Explanation

A pressure vacuum breaker's air inlet must be able to open to atmosphere when supply pressure drops. Continuous downstream pressure can hold the air inlet closed, so the device cannot break a vacuum and backsiphonage protection is lost.

Question 36Cross-connection control and backflow prevention

A tester cannot achieve the required pressure differential across the first check of a reduced pressure principle assembly during a field test. Which action is most appropriate?

  1. Investigate for a fouled check, debris, or incorrect test procedure before failing the assembly Correct answer.
  2. Record the result as passing and note the discrepancy
  3. Increase the supply pressure until the reading appears
  4. Bypass the assembly temporarily

Explanation

Failure to reach the required differential may result from a fouled or damaged check, debris in the test cock, or an incorrect test setup. The tester should investigate these causes before recording a failure, and should never falsify or bypass results.

Question 37Cross-connection control and backflow prevention

A double check valve assembly is installed on a line where downstream pressure can exceed supply pressure. Which condition does this assembly protect against?

  1. Both backpressure and backsiphonage Correct answer.
  2. Backpressure only
  3. Neither condition
  4. Backsiphonage only

Explanation

A double check valve assembly uses two independently acting check valves to resist both backsiphonage and backpressure. It is limited to low-hazard applications because it has no relief valve or atmospheric vent.

Question 38Cross-connection control and backflow prevention

Which condition is most likely to cause backsiphonage in a distribution system serving a large facility?

  1. A closed valve downstream of a pump
  2. A check valve stuck in the closed position
  3. A sudden main break that drops system pressure Correct answer.
  4. A thermal expansion tank on a water heater

Explanation

A main break or other event that causes a sudden loss of supply pressure can create a partial vacuum that draws nonpotable water through cross-connections. Backsiphonage depends on a pressure drop in the supply, not on downstream pressure sources.

Question 39Cross-connection control and backflow prevention

A facility has a high-hazard process and a low-hazard process on separate branches from the same potable main. Which protection strategy is generally most appropriate?

  1. Isolation of each hazard at its point of connection with devices matched to the hazard Correct answer.
  2. No protection for the low-hazard branch
  3. A single double check assembly at the meter
  4. A hose bibb vacuum breaker on each branch

Explanation

Point-of-use isolation with devices matched to the degree of hazard provides the most reliable protection because each cross-connection is controlled close to its source. Containment protection alone may not address internal cross-connections within the facility.

Question 40Cross-connection control and backflow prevention

A tester is documenting a field test for submission to the water purveyor. Which element is most essential to make the record traceable?

  1. The color of the device
  2. The name of the installer
  3. The tester's certification number and the date of the test Correct answer.
  4. The building's occupancy type

Explanation

A traceable test record identifies who performed the test, their certification, and when it occurred, along with the device and results. This allows the purveyor to verify that a qualified person performed the test at a specific time.

Question 41Cross-connection control and backflow prevention

An irrigation system is directly connected to a potable supply with no backflow protection. Which risk is most significant?

  1. The sprinkler heads may clog
  2. The water bill may increase
  3. Fertilizer and pesticides in the soil may be drawn into the potable supply during a pressure loss Correct answer.
  4. The irrigation timer may fail

Explanation

An unprotected irrigation connection can allow fertilizers, pesticides, and soil-borne organisms to be backsiphoned into the potable supply when pressure drops. This is a health hazard, which is why irrigation systems require appropriate backflow protection.

Question 42Cross-connection control and backflow prevention

A reduced pressure principle assembly discharges continuously from its relief valve. Which condition is the most likely cause?

  1. The first check is fouled or the relief valve is stuck open Correct answer.
  2. The assembly is installed above grade
  3. The second check is holding too tightly
  4. The supply pressure is too low

Explanation

Continuous discharge from the relief valve usually indicates a fouled or damaged first check that allows pressure to bleed past, or a relief valve stuck open. Both conditions cause the relief valve to sense a differential that keeps it discharging.

Question 43Cross-connection control and backflow prevention

A facility installs a reduced pressure principle assembly in a pit below grade. Which concern most directly affects compliance with installation requirements?

  1. The relief valve discharge may be subject to flooding or backpressure Correct answer.
  2. The pit may be too shallow for the piping
  3. The pit may be too brightly lit
  4. The assembly may be too far from the meter

Explanation

A reduced pressure principle assembly must be installed where its relief valve discharge is not subject to flooding, backpressure, or freezing. A below-grade pit can allow water to submerge the relief port, which compromises the air gap and violates installation requirements.

Question 44Cross-connection control and backflow prevention

A water purveyor requires containment protection at the meter for a facility with internal high-hazard processes. What does this requirement primarily accomplish?

  1. It guarantees that internal plumbing is code compliant
  2. It replaces the need for annual testing
  3. It protects the public main from contamination originating within the facility Correct answer.
  4. It eliminates the need for internal point-of-use protection

Explanation

Containment protection at the meter prevents contamination from the facility's internal systems from reaching the public main. It does not eliminate internal cross-connections, so point-of-use protection and testing remain necessary.

Question 45Cross-connection control and backflow prevention

Which device is most appropriate for protecting a potable supply at a laboratory sink where a hose may be submerged in a chemical bath?

  1. A double check valve assembly
  2. A hose bibb vacuum breaker with the hose kept above the bath Correct answer.
  3. An atmospheric vacuum breaker on a continuously pressurized line
  4. A pressure vacuum breaker

Explanation

A hose bibb vacuum breaker at the outlet protects against backsiphonage, and keeping the hose end above the bath prevents a submerged cross-connection. This combination addresses the hazard at the point of use where chemicals are present.

Question 46Cross-connection control and backflow prevention

A tester finds that a pressure vacuum breaker's check element does not hold the required differential. Which conclusion is most defensible?

  1. The device passes if the supply pressure is high
  2. The device fails only if water leaks externally
  3. The device passes because the air inlet still opens
  4. The device fails the test and requires repair or replacement Correct answer.

Explanation

The check element must hold the manufacturer's required differential for the device to pass. Failure to hold that differential means the device does not meet performance requirements and must be repaired or replaced before being placed back in service.

Question 47Cross-connection control and backflow prevention

A site has two cross-connections: a low-hazard heating loop and a high-hazard laboratory line. Which approach best reflects the principle of matching protection to hazard?

  1. Use a reduced pressure principle assembly for the lab and an appropriate lower-level device for the heating loop Correct answer.
  2. Use a double check assembly for both connections
  3. Use a reduced pressure principle assembly for both connections
  4. Use no protection for the heating loop because it is low hazard

Explanation

Protection should match the degree of hazard: a high-hazard lab line needs the highest mechanical protection, while a low-hazard heating loop may be adequately protected by a lower-level device such as a double check assembly. Overprotecting both is unnecessary, and leaving either unprotected is not acceptable.

Question 48Cross-connection control and backflow prevention

During a field test, a tester observes that the relief valve of a reduced pressure principle assembly opens at the correct differential but the second check does not hold. Which interpretation is most accurate?

  1. The assembly passes if the first check holds
  2. The assembly fails only if the relief valve also fails
  3. The assembly fails because both checks must hold their required differentials Correct answer.
  4. The assembly passes because the relief valve is the only critical component

Explanation

A reduced pressure principle assembly passes only when the relief valve and both check valves meet their required values. A second check that does not hold its differential is a failure even if the relief valve opens correctly.

Question 49Cross-connection control and backflow prevention

A facility proposes to eliminate a reduced pressure principle assembly and rely on a downstream air gap instead. Which statement best evaluates this proposal?

  1. An air gap cannot protect against backpressure
  2. An air gap is always inferior to a mechanical device
  3. An air gap can provide equivalent or better protection if it is properly sized and maintained Correct answer.
  4. An air gap requires annual differential testing

Explanation

A properly sized and maintained air gap is an effective means of protection and can provide protection equal to or better than a mechanical device because it has no moving parts to fail. It must be inspected to ensure the gap is maintained and not bypassed.

Question 50Cross-connection control and backflow prevention

A tester is asked to test a device that has no manufacturer's performance data available on site. Which action is most appropriate?

  1. Test using assumed values and record them as manufacturer specifications
  2. Skip the test and mark the device as passing
  3. Test only the relief valve
  4. Obtain the manufacturer's required values before completing the test Correct answer.

Explanation

Field test results must be compared against the manufacturer's specified performance values for that model. If those values are unavailable, the tester should obtain them before completing and certifying the test rather than assuming values.