Backflow Prevention Flashcards
7 cards from real Journeyman Plumbers Exam practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Backflow Prevention flashcards as text
An air gap is the physical separation between a water supply outlet and the flood level rim of a receiving vessel. What is the minimum air gap for a 1-inch supply pipe?
Answer: 2 inches
The minimum air gap is twice the effective opening of the supply pipe, so a 1-inch pipe requires at least a 2-inch air gap.
Which backflow prevention method provides the highest level of protection for a potable water supply?
Answer: Air gap
An air gap is the only method that provides complete physical separation between the supply and potential contamination, making it the highest level of protection.
A spill-resistant pressure vacuum breaker (SVB) differs from a standard PVB in that it:
Answer: Can be installed indoors because it contains the water discharged during operation
The spill-resistant PVB contains a specially designed body that prevents the relief discharge from spilling, making it suitable for indoor installations.
On a fire sprinkler system connected to the potable supply, the isolation valves on the backflow preventer assembly must be which type?
Answer: Indicating-type valves (OS&Y or butterfly with tamper switch)
Fire system isolation valves must be indicating-type (such as OS&Y gate valves or supervised butterfly valves) so it can be visually confirmed whether they are open or closed.
If a reduced pressure zone assembly's relief port is discharging continuously during normal system operation, this most likely indicates:
Answer: A failed or fouled check valve allowing pressure differential to drop below 2 psi
Continuous discharge from the relief port indicates that the differential pressure across the first check has dropped below the 2 psi threshold, typically due to a failed or debris-fouled check valve.
Which installation configuration is acceptable for a pressure vacuum breaker (PVB)?
Answer: Installed upstream of any chemical injection points
The PVB must always be installed upstream of any chemical injection or potential contamination source to provide protection.
What organization publishes the Uniform Plumbing Code (UPC) that governs backflow prevention requirements in many US jurisdictions?
Answer: International Association of Plumbing and Mechanical Officials (IAPMO)
The Uniform Plumbing Code (UPC) is published by IAPMO and is adopted by many western US states as the governing plumbing standard.