PC Backflow Prevention & Cross-Connection Control 2 — Questions and Answers
Question 1: How frequently must testable backflow prevention assemblies be inspected and tested in most U.S. jurisdictions?
- Every 5 years during routine permit inspections
- Every 6 months by the water utility
- At least annually by a certified backflow tester (Correct answer)
- Monthly by the building maintenance staff
Correct answer: At least annually by a certified backflow tester
Most jurisdictions require testable backflow prevention assemblies to be inspected and tested at least once per year by a certified backflow prevention assembly tester.
Question 2: What distinguishes a reduced pressure zone (RPZ) assembly from a double check valve assembly (DCVA)?
- The RPZ uses three check valves instead of two
- The RPZ includes a differential pressure relief valve between its two check valves (Correct answer)
- The RPZ requires no annual testing unlike the DCVA
- The RPZ can only be installed in a vertical orientation
Correct answer: The RPZ includes a differential pressure relief valve between its two check valves
The RPZ assembly includes a differential pressure relief valve in the zone between the two check valves that opens and discharges to atmosphere if either check valve fails or leaks.
Question 3: A double check valve assembly (DCVA) is approved for which hazard classification?
- High-hazard cross-connections only, such as chemical systems
- Low-to-moderate hazard cross-connections (Correct answer)
- Any hazard level including toxic chemical connections
- Non-hazardous decorative water features only
Correct answer: Low-to-moderate hazard cross-connections
DCVAs are approved for low-to-moderate hazard cross-connections (such as irrigation without chemical injection or fire sprinklers without additives) but are not suitable for high-hazard applications.
Question 4: Which location is NOT acceptable for installing a pressure vacuum breaker (PVB)?
- Above the highest downstream sprinkler head
- In a below-grade pit or vault (Correct answer)
- On an outdoor lawn irrigation riser at least 12 inches above grade
- On a potable water supply to an irrigation system
Correct answer: In a below-grade pit or vault
PVBs cannot be installed below grade or in pits because the vent port opens to atmosphere when activated and could be submerged in water, negating its protective function.
Question 5: What is the primary purpose of a hose bib vacuum breaker installed on an outdoor faucet?
- To regulate and limit water pressure at hose bib connections
- To prevent contaminated water from backsiphoning through a connected garden hose (Correct answer)
- To filter sediment before it reaches the garden hose connection
- To automatically shut off water flow when the hose is disconnected
Correct answer: To prevent contaminated water from backsiphoning through a connected garden hose
Hose bib vacuum breakers prevent backsiphonage through garden hoses, which can be submerged in pools, chemical buckets, or other contaminated sources.
Question 6: Under most U.S. plumbing codes, who is authorized to perform the required testing of backflow prevention assemblies?
- Any currently licensed journeyman or master plumber
- The property owner or facilities manager with proper documentation
- A certified backflow prevention assembly tester holding an approved certification (Correct answer)
- Only a licensed professional engineer registered in the state
Correct answer: A certified backflow prevention assembly tester holding an approved certification
Testing must be performed by a specially certified backflow prevention assembly tester who has completed an approved training course and passed a certification examination.
Question 7: What is a spill-resistant pressure vacuum breaker (SVB) specifically designed to prevent?
- Backpressure from booster pumps in high-rise buildings
- Nuisance water spillage from the vent port during normal pressure fluctuations (Correct answer)
- Contamination from high-hazard chemical injection systems
- Freeze damage to vacuum breaker assemblies in cold climates
Correct answer: Nuisance water spillage from the vent port during normal pressure fluctuations
The SVB incorporates a poppet check valve at the vent port to prevent water from spilling during minor pressure fluctuations while still providing full backsiphonage protection.
PC Backflow Prevention & Cross-Connection Control 2
How frequently must testable backflow prevention assemblies be inspected and tested in most U.S. jurisdictions?