Journeyman Plumbers Exam Backflow Prevention 4

Question 1

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?

Accepted Answer

2 inches

Answer

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.

Question 2

Which backflow prevention method provides the highest level of protection for a potable water supply?

Accepted Answer

Air gap

Answer

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.

Question 3

A spill-resistant pressure vacuum breaker (SVB) differs from a standard PVB in that it:

Accepted Answer

Can be installed indoors because it contains the water discharged during operation

Answer

The spill-resistant PVB contains a specially designed body that prevents the relief discharge from spilling, making it suitable for indoor installations.

Question 4

On a fire sprinkler system connected to the potable supply, the isolation valves on the backflow preventer assembly must be which type?

Accepted Answer

Indicating-type valves (OS&Y or butterfly with tamper switch)

Answer

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.

Question 5

If a reduced pressure zone assembly's relief port is discharging continuously during normal system operation, this most likely indicates:

Accepted Answer

A failed or fouled check valve allowing pressure differential to drop below 2 psi

Answer

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.

Journeyman Plumbers Exam Practice Test

Journeyman Plumbers Exam Practice Test

Journeyman Plumbers Exam Backflow Prevention 4