BAT Backflow Assembly Tester Prevention Methods 3 — Questions and Answers
Question 1: A double check detector assembly (DCDA) is typically installed on which type of service connection?
- Residential domestic water service
- Fire sprinkler service lines (Correct answer)
- Irrigation systems with fertilizer injection
- Industrial cooling towers
Correct answer: Fire sprinkler service lines
The double check detector assembly is specifically designed for fire sprinkler systems because it provides backflow protection while also detecting unauthorized water usage through a small bypass meter.
Question 2: Under AWWA and USC FCCCHR guidelines, which hazard classification requires an air gap rather than a mechanical backflow preventer?
- Low hazard with backsiphonage potential only
- Cross-connections with continuous pressure conditions
- Connections to premises containing substances lethal at low doses with no feasible testable assembly (Correct answer)
- Medium hazard irrigation systems
Correct answer: Connections to premises containing substances lethal at low doses with no feasible testable assembly
An air gap is the only acceptable means of protection when the hazard involves substances lethal at very low concentrations (e.g., certain pesticides) and no mechanical assembly is deemed adequate by the administrative authority.
Question 3: What is the minimum required air gap distance above the flood level rim for a 1-inch diameter water supply inlet?
- 1 inch
- 2 inches (Correct answer)
- 3 inches
- 1/2 inch
Correct answer: 2 inches
ASME A112.1.2 specifies a minimum air gap of twice the inside diameter of the supply pipe, but no less than 1 inch; for a 1-inch pipe the required gap is 2 inches.
Question 4: A spill-resistant pressure vacuum breaker (SVB) differs from a standard PVB primarily because:
- It can be installed below the highest outlet
- Its air-inlet valve is internally loaded and will not spill if pressure drops suddenly (Correct answer)
- It has two check valves instead of one
- It includes a relief valve that discharges to a drain
Correct answer: Its air-inlet valve is internally loaded and will not spill if pressure drops suddenly
The spill-resistant PVB (ASSE 1056) uses a specially designed, internally loaded air inlet that prevents nuisance spilling when pressure fluctuates, while still protecting against backsiphonage.
Question 5: During an RP assembly No. 2 check valve test, the gauge holds steady after needle valve closure. What does this result indicate?
- Check valve #2 is leaking and the assembly fails
- Check valve #2 is holding tight and passes the test (Correct answer)
- The relief valve is stuck closed and needs repair
- Supply pressure is insufficient to complete the test
Correct answer: Check valve #2 is holding tight and passes the test
A steady (non-dropping) gauge reading after closing the needle valve during the No. 2 check test indicates check valve #2 is holding tight and meets the pass criterion.
Question 6: Which statement correctly describes the difference between backsiphonage and backpressure?
- Backsiphonage is caused by downstream pressure exceeding supply; backpressure is caused by negative supply pressure
- Backsiphonage results from negative pressure in the supply line; backpressure results from downstream pressure exceeding supply pressure (Correct answer)
- Both conditions only occur in irrigation systems
- Backpressure can only occur in systems without a check valve
Correct answer: Backsiphonage results from negative pressure in the supply line; backpressure results from downstream pressure exceeding supply pressure
Backsiphonage is driven by a sub-atmospheric (negative) pressure in the supply line, while backpressure occurs when downstream pressure exceeds supply pressure, both of which can drive contaminants into the potable supply.
Question 7: A reduced pressure detector assembly (RPDA) combines what two functions in a single installation?
- Air gap protection and pressure regulation
- RP backflow protection and fire flow metering/detection (Correct answer)
- Double check protection and chlorine injection
- Pressure vacuum breaking and flow control
Correct answer: RP backflow protection and fire flow metering/detection
The RPDA (ASSE 1047) provides reduced pressure zone backflow protection on fire service lines while incorporating a bypass detector meter to identify unauthorized water usage.
BAT Backflow Assembly Tester Prevention Methods 3
A double check detector assembly (DCDA) is typically installed on which type of service connection?