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An in-depth examination of backflow prevention principles and practices in plumbing systems. It covers topics such as atmospheric pressure, backpressure, backsiphonage, cross-connections, and various backflow prevention assemblies like atmospheric vacuum breakers, pressure vacuum breakers, double check valve assemblies, and reduced pressure principle assemblies. The document delves into the technical details of these assemblies, including their installation requirements, testing procedures, and maintenance considerations. It also addresses related plumbing code requirements and best practices for ensuring the safety and integrity of water supply systems. This comprehensive resource would be valuable for plumbing professionals, students, and anyone interested in understanding the critical role of backflow prevention in protecting public health and preventing water contamination.
Typology: Exams
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Containing a plumbing system from the public water supply requires backflow protection at the _______? A. Appliance or fixture B. Building foundation C. Irrigation system D. Service Connection E. Sprinkler riser - ANSWER Service Connection Backflow preventer manufacturers recommend that assemblies be field-tested annually and when_____? A. Installed B. Moved C. Repaired or Installed D. Shut down E. Water suppliers provide notice - ANSWER Repaired or Installed A differential pressure gauge reading of 0.2 psid is represented on water column sight tube by _____? A. 1/16 in. (0.16 cm) B. 1/2 in. (1.3 cm) C. 2 in. (5.1 cm) D. 3.5 in. (8.9 cm) E. 5.5 in. (14 cm) - ANSWER 5.5 in. (14 cm)
Pollution of a public water supply suggests the substance in the water is ____? A. Aesthetically bad B. Biological with virus only C. Lowering the pH below 1. D. Radiological E. Toxic - ANSWER Aesthetically bad Backsiphonage may occur when the pressure inside copper tubing is ____? A. Greater than atmospheric pressure B. Greater than barometric pressure C. Greater than 0 gauge pressure D. Less than absolute pressure E. Less than atmospheric pressure - ANSWER Less than atmospheric pressure A cross-connection may be a permanent piping arrangement or a(n) ____? A. Backflow preventer B. Church symbol C. OSHA hazardous area designation D. Railroad and highway intersection sign E. Temporary hose bibb connection - ANSWER Temporary hose bibb connection The isolation of a plumbing water system hazard requires____? A. Appliance protection B. Building quarantine C. High-hazard protection D. Meter protection E. Toxin monitoring - ANSWER Appliance protection
A direct cross-connection suggests the piping system may be subjected to ____? A. Backpressure or backsiphonage B. Backsiphonage only C. Periodic inspection D. Sustained pressure E. Toxic materials - ANSWER Backpressure or backsiphonage A pipe restriction's flow velocity increase may allow ____? A. Aspiration B. Backpressure C. Low turbulence D. Pressure head E. Pressure surges - ANSWER Aspiration Water supply contamination from backflow may result in ____? A. A bad taste B. Coloration C. Death D. Odor or smell E. Pipe wall mineral deposit flaking - ANSWER Death To prevent backflow, an atmospheric vacuum breaker is primarily designed to ____? A. Allow air into the outlet piping system B. Create an elevation loop above ground C. Introduce head loss D. Prevent backpressure E. Restrict velocity - ANSWER Allow air into the outlet piping system Atmospheric vacuum breakers will typically be located on ____?
A. Commercial irrigation systems B. Fire-suppression systems C. Plumbing fixtures or appliances D. Utility storage tanks E. Water service connections - ANSWER Plumbing fixtures or appliances The mechanical component of an atmospheric vacuum breaker serves as an air-inlet valve and a ____? A. Check valve B. Regulating valve C. Relief valve D. Shut-off valve E. Test port - ANSWER Check valve A deck-mounted atmospheric vacuum breaker's critical installation level is above the outlet usage by ___? A. 1 in. (2.5 cm) B. 3 in. (7.6 cm) C. 6 in. (15 cm) D. 12 in. (30 cm) E. 18 in. (46 cm) - ANSWER 1 in. (2.5 cm) A hose-bibb connection is required to have a permanently installed ____? A. Atmospheric vacuum breaker B. Backflow preventer C. Pressure vacuum breaker D. Shut-off valve E. Spill-resistant vacuum breaker - ANSWER Atmospheric vacuum breaker Atmospheric vacuum breakers must not be subject to continuous water pressure for more than ___ hr.
A submerged atmospheric vacuum breaker may be considered a(n) _____? A. Backflow preventer B. Cross-connection C. Expensive elbow D. Typical installation E. Useful training photo - ANSWER. Cross-connection Flow from the outlet of an atmospheric vacuum breaker must not reach a _____? A. Closed tank B. Section of straight tubing C. Submerged inlet D. Toxic substance E. Valve - ANSWER Valve An atmospheric vacuum breaker is not required to have a(n) _____? A. Annual field test B. Installation elevation C. Installation inspection D. Label E. Usage limitaion - ANSWER Annual field test The air-inlet valve of an atmospheric vacuum breaker is help closed by____? A. Atmospheric pressure
B. Cotter pins C. Gravity D. Spring tension E. Water pressure - ANSWER Water pressure Pressure vacuum breaker shut-off valves and test cocks will avoid freeze damage if winterized by ____? A. Leaving all valves fully open B. Rotating ball valve handles to 45 degree angle C. Purging the body with compressed air D. Removing the assembly's internal components E. Removing shut-off valve and test cock operators - ANSWER Rotating ball valve handles to a 45 degree angle A supply pressure loss with a functional check valve will cause a pressure vacuum breaker to ____? A. Admit air into the downstream piping B. Be subject to backpressure C. Discharge water D. Fail E. Retain water pressure downstream of the check valve - ANSWER Retain water pressure downstream of the check valve If not marked, a pressure vacuum breaker's critical level is ____? A. At the bottom of the valve body B. Measured from the check valve inlet C. Measured from the body outlet D. Not important E. The air-inlet valve opening - ANSWER At the bottom of the valve body A pressure vacuum breaker may have ____ on the assembly's discharge piping.
A. Auxiliary water supply looped irrigation B. A boiler C. A booster pump D. Elevated piping E. Irrigation sprinkler heads - ANSWER Irrigation sprinkler heads The minimum loading to open a pressure vacuum breaker's air-inlet valve is ____? A. 1 psi (6.89 kPa) B. 2 psi (13.8 kPa) C. 3 psi (20.7 kPa) D. 4 psi (27.6 kPa) E. 5psi (34.5 kPa) - ANSWER 1 psi (6.89 kPa) The recorded value of a pressure vacuum breaker check valve is determined when ____? A. Both shut-off valves are closed B. The high-bleed valve is opened C. The air-inlet valve opens D. Water stops flowing from test cock 1 E. Water stops flowing from test cock 2 - ANSWER Water stops flowing from test cock 2 Pressure vacuum breaker shut-off valves must be _____ valves. A. Angle B. Gate C. Globe D. Regulating E. Tightly closed - ANSWER Tightly closed An indication that a pressure vacuum breaker is undersized for its application is _____? A. Air-inlet valve leakage
B. Bonnet distortion C. Chatter or noise during flow D. Disc pitting E. Spring elongation - ANSWER Chatter or noise during flow Continuous flow from a pressure vacuum breaker's test cock 2 with shut-off valve 2 open and shut-off valve 1 closed is an indication of _____? A. Backpressure backflow B. Backsiphonage backflow C. A failed air-inlet valve D. A leaking check valve E. A leaking or damaged shut-off valve 1 - ANSWER Backpressure backflow Pressure vacuum breakers may be used on the following applications except ____? A. High hazard/backsiphonage B. High hazard/continuous pressure C. Low hazard/backpressure D. Low hazard/backsiphonage E. Low hazard/intermittent pressure - ANSWER Low hazard/backpressure A double check valve assembly is installed 12 in. (30.5 cm) above the floor for _____? A. Electrical code compliance B. Floor draining C. Maintenance D. Mechanical code compliance E. Rodent control - ANSWER Maintenance Double check valve assembly product performance standards require venting for _____? A. Chemicals
B. Test cock corrosion C. Trapped air D. Vertical installations E. Winterization - ANSWER Trapped air A low-hazard use only backflow preventer is a(n) _____? A. Air-gap separation B. Atmospheric vacuum breaker C. Double check valve assembly D. Pressure vacuum breaker assembly E. Reduced pressure principle assembly - ANSWER Double check valve assembly Double check detector assembly flow indicators must register flow up to _____? A. 1 gpm (3.8 l/min) B. 2 gpm (7.6 l/min) C. 3 gpm (11.4 l/min) D. 4 gpm (15.1 l/min) E. 5 gpm (18.9 l/min) - ANSWER 2 gpm (7.6 l/min) A field test report for a double check valve assembly will include the manufacturer's name, model, size, and _____? A. Body material B. Date of manufacture C. Serial number D. Working pressure (maximum) E. Working temperature (maximum) - ANSWER Serial number Double check valve assembly components must be _____? A. Bronze
B. Independently acting C. Plastic D. Rubber E. Spring activated - ANSWER Independently acting After the repair of a double check valve assembly, a field test is required for the _____? A. Check valve number 1 B. Component repaired C. Entire assembly D. Tester's personal records only E. Shut-off valve tightness - ANSWER Entire assembly Prior to testing the check valves in the direction of flow on a double check valve assembly using a high and low side on the gauge, a tester must first ____? A. Determine the tightness of shut-off valve number 2 B. Notify the owner of the water shut-off C. Record the water supply line pressure D. Submit the test report to the water supply E. Test check valve number 2 with backpressure - ANSWER Determine the tightness of shut-off valve number 2 A double check valve assembly installed in a vertical flow down orientation is only allowed ______? A. In a basement or vault B. If the assembly was tested and approved as such C. If the check weight does not compress the spring D. On fire-suppression systems E. On water supply service connections - ANSWER If the assembly was tested and approved as such A check valve field test reported value of 0.8 psid (5.5 kPa) suggests _____?
A. A passing check valve B. A broken or failed spring C. Debris in the check seat D. Disc softening or decay E. Low water pressure - ANSWER Disc softening or decay A reduced pressure principle assembly's relief valve is loaded to _____? A. Push the valve away from its seat B. Push the valve on to its seat C. Remain closed with any zone pressure D. Remain open with any supply pressure E. Sustain all water hammer conditions - ANSWER Push the valve away from its seat The purpose of the reduced pressure principle assembly check valve number 1 loading is to _____? A. Create a pressure head increase B. Create a reduction in water pressure C. Provide water pressure to the relief valve diaphragm D. Reduce system pressure to the plumbing code limit E. Sustain the assembly's buffer - ANSWER Create a reduction in water pressure Intermittent relief valve discharge from a reduced pressure principle assembly is probably caused by _____? A. A fouled check valve number 1 B. A fouled check valve number 2 C. A fouled relief valve D. A partially closed shut-off valve number 2 E. Water hammer or hydraulic shock - ANSWER Water hammer or hydraulic shock Backpressure to a reduced pressure principle assembly fouled check valve number 2 will likely _____?
A. Dissipate through the air-vent B. Force the relief valve to open and discharge C. Have no visible effect D. Push the check valve closed E. Remain in the system - ANSWER Force the relief valve to open and discharge An air-gap separation must be maintained at a reduced pressure principle assembly's _____? A. Build drain B. Domestic Supply C. Indirect drain outlet D. Relief valve discharge E. Stationary sensor - ANSWER Relief valve discharge A reduced pressure principle assembly's buffer can be described as a ____? A. Soft-seated check upstream of the assembly B. Difference between the values for check valve 1 and check valve 2 C. Difference between the check valve 1 loading and the relief valve opening point D. Difference between the relief valve opening point and check valve 2 E. Sum of the check valve 1 loading and the relief valve divided by 2 - ANSWER Difference between the check valve 1 loading and the relief valve opening point When a reduced pressure principle assembly is installed vertically, the relief valve discharge must be _____? A. To a floor drain 2 times the piping size B. Higher than check valve number 1 C. Lower than check valve number 1 D. Lower than check valve number 2 E. Piped with the flow directed down - ANSWER Lower than check valve number 1
The maximum protection provided by a reduced pressure principle assembly is ____? A. High hazard/backpressure B. High hazard/backsiphonage C. High hazard/backpressure or backsiphonage D. Low hazard/backpressure E. Low hazard/backpressure or backsiphonage - ANSWER High hazard/backpressure or backsiphonage The reduced pressure principle assembly's number 2 check valve is loaded to close the valve with a minimum differential pressure of _____? A. 1 psid (6.9 kPa) B. 2 psid (13.9 kPa) C. 3 psid (20.7 kPa) D. 4 psid (27.6 kPa) E. 5 psid (34.5 kPa) - ANSWER 1 psid (6.9 kPa) If a reduced pressure principle assembly's field test shows a leaking shut-off valve 2, the leak may be compensated by obtaining water pressure/flow from ____? A. A high-pressure gauge control valve B. A low-pressure gauge control valve C. Test cock number 1 D. Test cock number 2 E. Test cock number 3 - ANSWER Test cock number 1 An air-gap separation will tend to _____? A. Admit air into the system to break a siphon B. Allow air to backpressure instead of liquid C. Dissipate chlorine residual D. Generate a whistle to warn of a siphon E. Provide code compliance - ANSWER Admit air into the system to break a siphon
Technically, the air-gap separation dimension is determined from the ____? A. Discharge pipe's outer diameter B. Effective opening C. Fixture inlet diameter D. Supply pipe diameter E. Service connection size - ANSWER Effective opening When a piping discharge is near a wall, the air-gap separation must be increased an additional ____ pipe diameter(s). A. 1 B. 2 C. 3 D. 4 E. 5 - ANSWER 1 An air-gap separation's hazard classification is _____? A. High hazard/backsiphonage B. High hazard/backpressure C. Low hazard/backsiphonage D. Low hazard/backpressure E. High or low hazard/backsiphonage only - ANSWER High or low hazard/backsiphonage only With the exception of a drinking fountain, the minimum air-gap separation is _____? A. 0.5 in. (1.3 cm) B. 1.0 in. (2.5 cm) C. 1.5 in. (3.8 cm) D. 2.0 in. (5.1 cm) E. 3.0 in. (7.6 cm) - ANSWER 1.0 in. (2.5 cm)
Water discharged through an air gap to an open tank surface has a pressure of ____? A. 0 psi absolute B. 0 psi atmospheric C. 0 psi gauge D. Static line pressure E. Vapor pressure - ANSWER 0 psi atmospheric Air-gap separations must be ____? A. Classified B. Inspected annually C. Laboratory listed D. Tested and repaired E. Tested with a sight tube - ANSWER Inspected annually When close to two intersecting walls, an air-gap separation is increased from 2 diameters to _____ diameters. A. 2. B. 3 C. 3. D. 4 E. 4.5 - ANSWER 4 An air-gap separation is mandatory between the potable supply and a(n) _____? A. Bakery dough mixer B. Isolation assembly C. Pressure washer D. Sanitary sewer E. Water meter - ANSWER Sanitary sewer
Toxins may enter a water supply pipe air-gap separation through the ____? A. Atmosphere B. Control valve C. Pressure tank D. Receiving vessel E. Sanitary sewer - ANSWER Atmosphere A properly installed barometric loop will prevent _____? A. Backpressure B. Backsiphonage C. Freezing D. Leakage E. Surges - ANSWER Backsiphonage A swing connection is a type of _____? A. Backflow preventer B. Cross-connection C. Detector assembly D. Gauge component E. Shut-off valve repair tool - ANSWER Cross-connection A barometric loop must be installed 35 ft (10.7 m) above the highest ____? A. Boiler B. Fixture outlet C. Gate valve D. Service connection E. Water meter - ANSWER Fixture outlet
A spool is used to connect a ____? A. Copper and ductile iron pipe B. Copper and PVC pipe C. Disc retainer and valve guide D. Potable and non-potable system E. Test cock - ANSWER Potable and non-potable system A fire sprinkler system's backflow protection for a black-iron pipe system is typically ____? A. An air-gap separation B. A double check valve assembly C. A reduced pressure principle assembly D. A reduced pressure detector assembly E. No protection required - ANSWER A double check valve assembly The dual check with an intermediate vent is used primarily for ____? A. Commercial boilers B. Industrial process water piping C. Hose bibbs D. Low-pressure residential boilers E. Swimming pool chlorinators - ANSWER Low-pressure residential boilers A hose connection vacuum breaker's maintenance includes _____? A. Check disc replacement B. Diaphragm replacement C. Draining for winterization D. Replacement every 2 years E. Water flushing - ANSWER Draining for winterization Pressure loss per foot of elevation rise is ____?
A. 0.43 psi (2.99 kPa) B. 0.50 psi (3.45 kPa) C. 1.0 psi (6.89 kPa) D. 2.0 psi (13.9 kPa) E. 2.3 psi (15.9 kPa) - ANSWER 0.43 psi (2.99 kPa) When the water velocity increases, the ____? A. Atomospheric pressure decreases B. Gauge pressure decreases C. Gauge pressure increases D. Head loss does not change E. Water temperature lowers - ANSWER Gauge pressure decreases An indirect cross-connection suggests the system may be subject to ____? A. An air gap separation B. Backpressure C. Backsiphonage only D. A meniscus E. A Venturi - ANSWER Backsiphonage only A reduced pressure principle assembly's continuous discharge from a relief valve and a gauge reading of 4 psid to 5 psid may indicate _____? A. A damaged check 1 guiding member B. Debris fouling check valve number 1 C. A leaking shut-off valve number 2 D. Leakage through the diaphragm E. A weak or broken spring - ANSWER Debris fouling check valve number 1
If a reduced pressure principle assembly's relief valve opens at a differential pressure of 5.5 psid, the reason may be a(n) _____? A. Brushing or stem is worn B. Damaged check valve seat C. Dirty or damaged relief valve seat or disc D. Outlet shut-off valve is leaking with backpressure E. Misaligned or broken relief valve spring - ANSWER Dirty or damaged relief valve seat or disc Confined space air monitors will sound if the oxygen percentage is less than _____%. A. 18. B. 18. C. 19. D. 19. E. 20.0 - ANSWER 19. An irrigation sprinkler with chemical injection will require a(n) _____? A. Air-gap separation B. Atmospheric vacuum breaker C. Double check valve assembly D. Pressure vacuum breaker assembly E. Reduced pressure principle assembly - ANSWER Reduced pressure principle assembly While obtaining a reduced pressure principle assembly's relief valve opening point using a high and low- pressure hose, turning the gauge valve more than 1/4 turn indicates a leaking _____? A. Check valve B. Gauge Valve C. Relief valve D. Shut-off valve E. Test cock - ANSWER Shut-off valve
A reduced pressure principle assembly check valve number 1 is field-tested _____? A. In the direction of flow only B. Under backpressure C. Under backsiphonage D. Under backpressure and the direction of flow E. Under backpressure and backsiphonage - ANSWER In the direction of flow only A thrust block is designed to ____? A. Adjust pressure changes B. Maintain pipe joint integrity C. Stop backflow D. Stop water hammer E. Support failing soil conditions - ANSWER Maintain pipe joint integrity Water hauling truck fill stations should have either an air-gap separation or a(n) _____? A. Atmospheric vacuum breaker B. Double check valve assembly C. Dual check valve D. Pressure vacuum breaker assembly E. Reduced pressure principle assembly - ANSWER Reduced pressure principle assembly When testing a reduced pressure principle assembly using three hoses, a difference between the apparent and actual reading is likely due to _____? A. Backflow B. Check valve failure C. Disc compression D. A leaking shut-off valve E. Opening of the bypass control valve - ANSWER A leaking shut-off valve
The plumbing code requires that a spill-resistant vacuum breaker be installed above the highest use by at least _____? A. 3 in. (7.6 cm) B. 6 in. (15 cm) C. 9 in. (23 cm) D. 12 in (30 cm) E. 18 in. (46 cm) - ANSWER 12 in (30 cm) Modifications of any kind to a backflow preventer will _____? A. Alter its head loss B. Render it inoperable C. Require a tester failure D. Validate its warranty E. Void its approval - ANSWER Void its approval A water system pressure of 10 psi (69 kPa) and a plumbing system pressure of 20 psi (138 kPa) may be described as _____? A. Backpressure B. Backsiphonage C. Gauge pressure differential D. inflow/infiltration E. Static condition - ANSWER Backpressure According to ANSI standard, potable water pipe marking requirements are _____ lettering. A. Blue background with white B. Green background with white C. Green background with yellow D. White background with blue
E. White background with green - ANSWER Green background with white A water closet ball cock must be installed above the opening of the overflow pipe by at least _____? A. 1.0 in. (2.5 cm) B. 1.5 in. (3.8 cm) C. 2.0 in. (5.1 cm) D. 2.5 in. (6.4 cm) E. 3.0 in. (7.6 cm) - ANSWER 1.0 in. (2.5 cm) Gauges used for field tests of backflow preventers must have the calibration checked ____? A. After every 50 tests B. Annually C. If dropped D. If used in temperature extremes E. With water - ANSWER Annually New backflow prevention assemblies should be tested ____? A. Before failure B. Before the expiration of the warranty C. Before being placed into the system D. In the presence of a plumbing inspector E. Monthly - ANSWER Before the expiration of the warranty A common backflow preventer on a double-wall heat exchanger with leak detection is ____? A. An air-gap separation B. An atmospheric vacuum breaker C. A double check valve assembly D. A reduced pressure principle assembly E. Nothing - ANSWER Nothing
A recommended containment backflow preventer for a restricted or classified facility is a _____? A. Dual check valve B. Dual check with an intermediate vent C. Double check valve assembly D. Pressure vacuum breaker E. Reduced pressure principle assembly - ANSWER Reduced pressure principle assembly Plumbing codes require that water system pressures do not exceed ____? A. 20 psi (138 kPa) B. 60 psi (414 kPa) C. 80 psi (555 kPa) D. 100 psi (690 kPa) E. 120 psi (827 kPa) - ANSWER 80 psi (555 kPa) Two valves of a five-valve differential pressure gauge are used to ____? A. Bypass water for a leaky shut-off valve B. Compensate for leaks C. Purge trapped air from the gauge D. Reset the gauge calibration E. Stop backflow during a field test - ANSWER Purge trapped air from the gauge If testing a double check valve assembly check valve with a water column, the maintained water column height must be at least _____? A. 24 in. (61 cm) B. 28 in. (71 cm) C. 32 in. (81 cm) D. 36 in. (91 cm) E. 40 in. (102 cm) - ANSWER 28 in. (71 cm)
Before testing a backflow preventer, the test cocks are flushed primarily to _____? A. Clean dirt and possible corrosion buildup B. Create a water flow condition C. Purge air from the assembly D. Reduce pressure differentials E. Verify water pressure - ANSWER Clean dirt and possible corrosion buildup If testing a backflow preventer using a differential gauge and a single hose, it is important to ____? A. Keep the high and low manifold valves open B. Maintain the gauge and hose connections at the same height as the assembly C. Open the high-pressure bleed valve before opening a test cock D. Open the low-pressure and bypass control valves E. Plug the bypass and low-pressure hose end connections - ANSWER Maintain the gauge and hose connections at the same height as the assembly When testing a backflow preventer, shut-off valve 2 is closed before shut-off valve 1 because _____? A. Failures in outlet valves are determined first B. It slows the rate of flow through the assembly C. The potential of backflow during the test is eliminated D. Venturi flow through the check will cavitate the assembly E. Water pressure will be maintained for testing - ANSWER Water pressure will be maintained for testing Plumbing codes define hot water as above _____? A. 100 degrees F (38 degrees C) B. 110 degrees F (43 degrees C) C. 140 degrees F (60 degrees C) D. 180 degrees F (82 degrees C) E. 210 degrees F (99 degrees C) - ANSWER 110 degrees F (43 degrees C)
Before the physical test of a backflow preventer may begin, the tester must first _____? A. Begin completing the test report form B. Conduct a downstream plumbing hazard inspection C. Obtain a repair kit D. Obtain permission to shut-down the water service E. Provide notice to the fire department - ANSWER Obtain permission to shut-down the water service If pressure vacuum breaker air-inlet valve does not open and the gauge indicator does not drop, a reason may be _____? A. A leaking shut-off valve 2 with a parallel installation B. A tightly closing shut-off valve number 1 C. The check valve is failed D. The high-pressure bleed valve is open E. The test cock is open - ANSWER A leaking shut-off valve 2 with a parallel installation A backflow preventer creates a closed plumbing system that requires the installation of a(n) _____? A. Expansion tank B. Globe valve C. Pressure reducing valve D. Temperature and pressure relief valve E. Utility box key - ANSWER Expansion tank When both shut-off valves are closed on a reduced pressure principle assembly and test cock 2 is opened, a tester should expect _____? A. Check valve number 1 to open B. Continuous flow from the test cock C. No flow from the test cock D. No result