PLUMBING DEFINITION OF TERMS

Air Gap

Unobstructed vertical distance through free atmosphere between the lowest water supply opening and the flood level rim.

Backflow

Flow into potable water pipes from a non-intended source.

Back Siphonage

Backflow due to negative pressure causing contaminated water to enter supply.

Battery of Fixtures

Two or more similar fixtures discharging into a common horizontal waste pipe.

Bib

Synonymous with faucet (preferred term).

Blind Flange

Closes pipe end with no opening.

Blow-Off

Controlled outlet used to discharge water.

Branch

Any piping other than main riser or stack.

Branch Interval

Storey height of stack, minimum 2.40 m, where horizontal branches connect.

Branch Vent

Vent connecting individual vents to a vent stack.

Calking

Plugging openings using oakum, lead, or similar materials.

Circuit Vent

Branch vent serving multiple traps, connected at last fixture.

Continuous Vent

Vertical extension of a drain serving as vent.

Combination Fixtures

Multiple sinks/trays in one fixture unit.

Combination Waste and Vent System

Horizontal wet venting using a common waste-vent pipe.

Common Vent

Single vent for two or three fixtures; dual vent.

Cross Connection

Physical connection between potable and non-potable systems.

Dead End

Closed pipe end allowing stagnation.

Developed Length

Length along pipe centerline including fittings.

Diameter

Nominal ID, except brass/copper = OD.

Drainage System

Piping conveying sewage or waste to legal disposal.

Dry Vent

Vent that carries air only, no waste.

Effective Opening

Minimum cross-sectional area of outlet (air gap basis).

Existing Work

Plumbing installed and approved prior to alteration.

Fixture Branch

Pipe connecting several fixtures.

Fixture Drain

Pipe from trap to another drain.

Fixture Supply

Pipe connecting fixture to supply branch.

Fixture Units

Numerical load value of fixtures.

Fixture Unit Flow Rate

Flow ÷ 7.5 gpm = unit flow.

Flood Level

Device maintaining tank water level for effective flushing.

Ferrule

Metal sleeve with removable plug for cleaning.

Flush Valve

Tank device for flushing water closets.

Flushometer Valve

Pressure-activated valve delivering fixed water volume.

Grade

Slope of pipe (inch per foot).

Group Vent

Vent serving two or more traps.

Horizontal Pipe

Pipe at more than 45° from vertical.

Invert

Lowest inside portion of a pipe.

Liquid Waste

Waste without fecal matter.

Local Vent Pipe

Removes foul air or vapor from fixture area.

Looped Vent

Circuit vent looping to stack vent.

Lateral

Secondary pipe; sewer receiving building sewer only.

Main

Principal artery of piping system.

Main Sewer

Sewer controlled by public authority.

Main Vent

Primary vent pipe of system.

Plumbing Fixtures

Devices receiving water or discharging waste.

Plumbing System

Entire water supply, drainage, and vent system within property.

Relief Vent

Provides air circulation between drainage and vent systems.

Re-Vent Pipe

Vent connected directly to fixture or waste.

Riser

Vertical supply pipe extending one storey or more.

Rough-In

Plumbing installation before fixtures are set.

Return Bend

180° pipe bend.

Public Sewer

Sewer with equal public connection rights.

Sanitary Sewage

Human excrement + household liquid waste.

Sanitary Sewer

Sewer for sanitary sewage only, no storm water.

Secondary Branch

Branch other than primary building drain.

Sewerage / Sewage Works

Collection to final disposal of sewage.

Siamese Connection

Y-connection for fire hoses.

Standpipe

Vertical water storage pipe, often pressurized.

Side Vent

Vent connected at ≤45° angle.

Soil Pipe

Pipe carrying water closet discharge.

Stack

Vertical main of soil, waste, or vent system.

Stack Group

Fixture layout to minimize venting.

Stack Vent

Extension of stack above highest branch.

Stack Venting

Venting through the soil or waste stack.

Subsoil Drain

Pipe carrying subsurface water only.

Sump

Pit at low point collecting liquid waste.

Trap

Liquid seal preventing back passage of air.

Trap Seal

Vertical depth of retained liquid.

Vent Stack

Vertical pipe for air circulation.

Vent System

Prevents siphonage and back pressure.

Vertical Pipe

Pipe at ≤45° from vertical.

Waste Pipe

Pipe carrying liquid waste only.