PC Backflow Prevention & Cross-Connection Control 1

Question 1

What is a cross-connection in a plumbing system?

Accepted Answer

Any physical link between a potable water supply and a potentially contaminated source

Answer

A cross-connection is any physical connection between a potable water system and a non-potable source that could allow contamination to enter the drinking water supply.

Question 2

What type of backflow occurs when negative pressure develops in a supply line and draws contaminants backward?

Accepted Answer

Backsiphonage

Answer

Backsiphonage occurs when a drop in supply pressure below atmospheric creates a siphon effect that pulls contaminants back into the potable water system.

Question 3

Which backflow prevention method provides protection solely through physical separation with no mechanical parts?

Accepted Answer

Air gap

Answer

An air gap is the only non-mechanical backflow prevention method, relying on physical separation between the water outlet and flood level rim to prevent contamination.

Question 4

What is the minimum air gap required between a water supply outlet and the flood level rim of a receiving fixture under most plumbing codes?

Accepted Answer

Twice the effective opening of the supply outlet, but not less than 1 inch

Answer

The required air gap is at least twice the effective opening (diameter) of the water supply outlet, with an absolute minimum of 1 inch to prevent backsiphonage.

Question 5

Which backflow prevention assembly is specifically required for high-hazard cross-connections to a public water supply?

Accepted Answer

Reduced pressure zone (RPZ) assembly

Answer

The reduced pressure zone assembly provides the highest level of mechanical protection and is required by code for high-hazard cross-connections due to its relief valve between two independent check valves.

(PC) Plumber Certification Practice Test

(PC) Plumber Certification Practice Test

PC Backflow Prevention & Cross-Connection Control 1