Blueprint Reading & Interpretation Flashcards

A plumbing drawing uses a scale of 1/8" = 1'-0". If a pipe run measures 3 inches on the drawing, what is the actual length?

Answer: 24 feet

At 1/8" = 1'-0", each inch on the drawing equals 8 feet, so 3 inches × 8 = 24 feet of actual pipe.

A detail drawing of an RPZ installation shows a 'RELIEF VALVE DRAIN' line directed to a floor drain with an 'A.G.' notation. What does 'A.G.' mean?

Answer: Air gap

A.G. on plumbing drawings stands for Air Gap, specifying that the relief valve discharge must terminate above the flood rim of the drain with an unobstructed air gap.

On a site plan, contour lines that are closely spaced near a backflow preventer vault indicate:

Answer: A steep slope that may require special drainage consideration

Closely spaced contour lines represent a steep grade change, which affects vault drainage design and surface runoff management.

A drawing revision cloud with a delta symbol (Δ) and the number '3' indicates:

Answer: The enclosed area was changed in revision 3

Revision clouds with delta symbols mark areas of change, and the number identifies which revision introduced that change.

On a plumbing legend, a symbol showing a circle with a diagonal line through it next to the letters 'PVB' represents:

Answer: A pressure vacuum breaker assembly

PVB is the standard abbreviation for Pressure Vacuum Breaker, a type of backflow preventer used for irrigation and non-continuous pressure applications.

When a blueprint shows a backflow preventer with the notation 'BY OWNER' in the drawing, this means:

Answer: The owner is responsible for furnishing and installing that item, not the contractor

'By Owner' is a scope designation indicating that the owner, not the general or plumbing contractor, is responsible for providing or installing that equipment.

A water system schematic uses a thick line for mains and a thin line for service connections. A backflow preventer symbol appears on a thin line feeding a building. This layout indicates:

Answer: The BFP is on the building service line, not the main

Line weight conventions distinguish distribution mains (heavy) from individual service connections (lighter), showing the BFP location on the service lateral.