PC Backflow Prevention & Cross-Connection Control 3

Question 1

Which scenario best represents a high-hazard cross-connection requiring an RPZ assembly?

Accepted Answer

A direct connection between potable water and a chemical mixing or processing tank

Answer

A connection between potable water and a chemical processing tank is a high-hazard cross-connection because contamination could cause serious illness or death, requiring the maximum protection of an RPZ.

Question 2

What action is required when an RPZ assembly's relief valve discharges water continuously during normal operation?

Accepted Answer

Remove the assembly from service and have it repaired or replaced by a certified tester

Answer

Continuous discharge from an RPZ relief valve indicates that one or both check valves have failed, and the assembly must be taken out of service immediately until repaired by a certified tester.

Question 3

At what minimum height above the highest downstream outlet must a pressure vacuum breaker (PVB) be installed?

Accepted Answer

12 inches above the highest outlet

Answer

PVBs must be installed at least 12 inches above the highest downstream outlet to protect against both backsiphonage and backpressure conditions.

Question 4

Why is thermal expansion a critical concern in a closed plumbing system that has a backflow preventer installed?

Accepted Answer

Heated water cannot expand back toward the meter, creating dangerous pressure increases that can damage water heaters and pipes

Answer

A backflow preventer creates a closed system; when a water heater heats the water, it expands but cannot push back toward the meter, causing pressure buildup that can damage the water heater and plumbing components.

Question 5

Which assembly or device would typically be required for a residential lawn irrigation system with a fertilizer injection system connected to the public water supply?

Accepted Answer

A reduced pressure zone (RPZ) assembly due to the chemical injection hazard

Answer

Fertilizer injection elevates the irrigation system to a high-hazard cross-connection because chemicals entering the potable supply pose a health risk, requiring an RPZ assembly.

(PC) Plumber Certification Practice Test

(PC) Plumber Certification Practice Test

PC Backflow Prevention & Cross-Connection Control 3