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 garden hose connected to an outdoor hose bib

Answer

A boiler makeup water line using only non-toxic glycol inhibitors

Answer

A lawn irrigation system with no chemical injection or fertilizer injection

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

Reduce the incoming water pressure to below 80 psi immediately

Answer

Open a nearby bypass valve to maintain water service to the building

Answer

Replace only the relief valve while keeping the assembly in service

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

6 inches above the highest outlet

Answer

18 inches above the highest outlet

Answer

24 inches above the highest outlet

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

Heat causes plastic pipes to off-gas chemicals into the water supply

Answer

Thermal expansion causes check valves in the backflow preventer to seize in the closed position

Answer

Hot water increases corrosion rates inside the backflow preventer assembly

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

A simple atmospheric vacuum breaker on each zone valve

Answer

A double check valve assembly installed at the meter

Answer

A hose bib vacuum breaker on the irrigation supply connection

Question 6

What is the precise definition of 'backflow' as used in plumbing and cross-connection control?

Accepted Answer

The undesirable reversal of water flow direction in a potable water distribution system

Answer

Any water that flows backward through a drain or sewer pipe

Answer

High-velocity water discharge from a pressure relief valve

Answer

Overflow from a fixture that exceeds the flood level rim

Question 7

Which installation requirement applies universally to ALL types of testable backflow prevention assemblies under U.S. plumbing codes?

Accepted Answer

They must be readily accessible for inspection, testing, and maintenance

Answer

They must be installed at least 5 feet above finished floor level

Answer

They must be housed in a temperature-controlled enclosure year-round

Answer

They must include a permanently installed bypass line for uninterrupted water service