NBOPE/IAPMO Master Plumber flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Water supply fixture unit

A dimensionless value assigned to each fixture representing its probable demand on the water supply; the total WSFU is converted to gpm using the demand table for sizing.

Drainage fixture unit

A value assigned to each fixture representing its probable discharge to the drainage system; the total DFU and slope determine the required drain size.

Trap seal depth

The vertical distance between the trap weir and the top of the trap dip, required to be 2 to 4 inches to prevent sewer gas from entering the building.

Air gap

The unobstructed vertical distance through free atmosphere between a potable water outlet and the flood level rim of a receptacle; the highest level of backflow protection.

Reduced pressure principle assembly

A testable backflow preventer with two independently acting check valves and a relief valve; it protects against both backsiphonage and backpressure at high-hazard connections.

Pressure vacuum breaker

A testable backflow preventer that protects against backsiphonage only; it must be installed at least 12 inches above the highest downstream outlet.

Thermal expansion tank

A tank installed on a closed potable water system to absorb the volume increase caused by heating water, preventing excess pressure and T&P valve discharge.

Temperature and pressure relief valve

A safety valve on a water heater that opens at a set temperature and pressure to prevent tank rupture; its discharge pipe must be full size and unobstructed.

Combustion air openings

Openings that supply air to fuel-burning appliances; the outdoor air method requires 1 square inch per 4,000 Btu/h for vertical ducts.

Sediment trap

A fitting installed at the appliance connection to collect dirt and debris before it reaches the gas controls; it must be installed per the manufacturer's instructions.

Developed length

The total length of pipe measured along the centerline, including fittings and valves; if unknown, add about 50 percent to the measured run for sizing.

Static pressure loss per foot

The pressure lost to elevation, approximately 0.433 psi per foot of rise, or 1 psi per 2.31 feet of vertical height.

Riser diagram

A schematic drawing showing the vertical arrangement of the plumbing system, including pipe sizes, fixture connections, vents, and the building drain.

Isometric drawing

A three-dimensional drawing used to interpret offsets, changes in elevation, and the route of piping through the building.

Schedule of values

A document that allocates the contract sum to work items and serves as the basis for progress payments during construction.

Retainage

A percentage of each progress payment withheld by the owner until final acceptance and completion of the punch list, commonly 5 to 10 percent.

Change order

A written document that modifies the scope, price, or schedule of the contract; it must be signed by the owner or representative before work proceeds.

Main vent through roof

The principal vent that extends through the roof to admit air to the drainage system; it must extend at least 6 inches above the roof.

Air admittance valve

A one-way valve that admits air into the drainage system to protect trap seals; it may replace certain vents where permitted by the adopted code.

Grease interceptor

A device installed on kitchen drainage to trap fats, oils, and grease before they reach the sewer; it must be accessible for cleaning.

Indirect waste receptor

A receptacle that receives waste through an air gap or air break from fixtures such as ice machines and sterilizers, preventing backflow to the fixture.

Secondary roof drainage

Overflow scuppers or drains sized for the design storm that provide a backup path for rainwater when the primary roof drains are blocked.

Medical gas certification

The requirement that medical gas piping be installed by a certified installer and verified by an independent third party before the system is placed in use.

Emergency eyewash station

A fixture that delivers tepid flushing fluid to the eyes and body within about 10 seconds of travel from a hazard, per the adopted safety standard.

Water supply demand curve

A table or curve that converts the total water supply fixture units to the probable peak demand in gallons per minute for pipe sizing.

Dielectric union

A fitting that separates dissimilar metals, such as copper and steel, to prevent galvanic corrosion at the connection in a piping system.

Cleanout

An accessible fitting with a removable plug that allows the drainage system to be cleared; required at the base of stacks and at changes of direction.

Rough-in inspection

The inspection of piping and venting installed in walls and floors before concealment; approval is required before covering the work.

Alternate method approval

The authority having jurisdiction may approve a material or method that is not specifically listed in the code if it is equivalent in performance and safety.

Flushometer valve pressure

Flushometer valves typically require a minimum flowing pressure of about 15 to 20 psi at the fixture to operate properly, per the manufacturer.

Fixture clearance

The minimum space around a fixture, such as 15 inches from a water closet centerline to a side wall and 30 inches of clear space in front.

Punch list

A list of incomplete or defective work prepared at substantial completion; final payment is typically released after the items are corrected.