NM Journeyman Plumber key terms

A unitless measure of the load a fixture places on the drainage or water supply system, roughly equal to one cubic foot per minute of flow, used to size pipes from tables rather than by counting fixtures.

The drainage load value assigned to a fixture based on its typical discharge rate and waste outlet size; values are added along a branch to select drain and sewer pipe sizes from code tables.

A loading value assigned to a fixture reflecting its probable hot and cold water demand; total values convert to gallons per minute for sizing supply piping and estimating pressure loss.

The total measured distance of pipe along its centerline from the source to the farthest outlet, including all vertical and horizontal runs but excluding fittings; used with tables to size water pipe.

The pressure lost as water moves through pipe, fittings, and valves because of resistance at the pipe wall; expressed in psi per 100 feet of pipe and increases sharply with higher flow velocity.

The pressure exerted by water at rest, determined by the height of the water column above the point measured; approximately 0.433 psi per foot of elevation.

The pressure remaining at a fixture or outlet while water is flowing, after elevation losses and friction losses are subtracted from the supply pressure; must meet the minimum required for the fixture.

A device installed on a water service where incoming pressure exceeds the code limit, reducing it to a safe downstream pressure and often including a strainer and bypass for thermal expansion relief.

The increase in water volume as it is heated in a closed system, which raises pressure; controlled by an expansion tank, a relief valve, or a bypass arrangement to prevent damage to piping and fixtures.

The unobstructed vertical distance between the lowest opening of a water supply outlet and the flood-level rim of the receiving fixture; the most reliable form of backflow protection.

An assembly that stops reverse flow of contaminated water into the potable supply, using check valves, relief valves, or reduced-pressure zones depending on the hazard level of the connection.

Any actual or potential link between the potable water system and a source of contamination or pollution; must be eliminated or protected by an approved backflow device.

A device that admits air into piping when pressure drops below atmospheric, breaking a siphon so contaminated water cannot be drawn back into the supply; common on hose bibbs and flush valves.

The edge of a fixture over which water would overflow onto the floor; it sets the reference height for air gaps and for the critical level of fixtures and standpipes.

The line on a fixture or tank marking the lowest point at which a backflow-prevention device or vacuum breaker must be installed to remain above the flood-level rim.

A receptacle, device, or appliance that receives water or waste and discharges it to the drainage system, such as a sink, water closet, bathtub, or floor drain.

The exposed fittings and controls on a fixture, including faucets, spouts, handles, showerheads, and stops; trim is finished work installed after the rough-in stage.

A toilet; a fixture that receives human waste and discharges it through a trapway to the drainage system, rated by flush volume and identified by bowl and tank or flushometer type.

A valve that uses line pressure to deliver a measured flush to a fixture, usually a water closet or urinal, requiring a minimum supply pressure and flow rate to operate correctly.

The depth of water held in a trap that blocks sewer gas from entering a building; typically required to be between two and four inches and protected from evaporation or siphonage.

A trap shaped so its outlet leg points downward and then horizontally, used on fixtures with a waste outlet in the bottom; it holds the trap seal and connects to the trap arm.

The section of pipe between a trap's outlet and its vent connection, sloped to drain and limited in length so the trap seal is not siphoned by flow.

A pipe that lets air into and out of the drainage system to equalize pressure, protect trap seals, and allow sewer gases to escape above the roof.

A vertical vent pipe extending through the roof that serves one or more fixtures or stacks below, providing relief air and carrying gases outdoors.

A one-way valve that opens to admit air into a drainage system when pressure drops and closes to prevent sewer gas escape; permitted only under stated conditions and access requirements.

A vertical pipe in the drainage system that carries waste from fixtures down to the building drain; a soil stack carries toilets, a waste stack carries other fixtures.

A vertical section of soil or waste stack one story in height, measured from where the horizontal branch connects to the stack to the next connection above it.

The lowest pipe of a drainage system that receives waste from stacks and branches inside the building and conveys it to the building sewer at or near the foundation wall.

The pipe carrying sewage from the building drain's end outside the foundation to the public sewer, private treatment system, or other point of disposal.

An accessible fitting with a removable plug or cover installed at the base of stacks, ends of horizontal runs, and changes in direction so blockages can be cleared with a cable.

The fall of a horizontal drain per unit of length, expressed in inches per foot or percent; it must be steep enough to move solids but not so steep that liquids outrun them.

A device that separates grease, oil, sand, or other materials from waste before it enters the drainage system, retaining the material for removal while letting the liquid pass.

A tank or fitting that cools kitchen waste and traps fats, oils, and grease at the surface while allowing clearer water to flow out; requires periodic pumping and correct venting.

Waste that needs treatment or a dedicated system because of temperature, corrosiveness, solids, or other characteristics, such as acid waste, chemical waste, or high-temperature discharge.

Liquid waste that discharges into the drainage system through an air gap or air break rather than a direct connection, used for fixtures where backflow or contamination is a concern.

A piping system that collects rainwater from roofs, areaways, and paved areas and carries it to a storm sewer, drywell, or other approved disposal point, separate from sanitary waste.

A fitting installed at a roof low point that admits rainwater into the storm drainage system, often with a strainer and a dome or gravel guard to keep debris out.

Perforated or open-joint pipe placed below grade to collect groundwater and relieve hydrostatic pressure around foundations, footings, and slabs, discharging to a sump or storm system.

A pump installed in a pit that removes collected groundwater or stormwater to an approved discharge point, typically controlled by a float switch and provided with a check valve.

A valve that closes automatically to stop sewage from a surcharged public sewer from backing into a building drain; may be required where the fixture elevation is low relative to the street.

An appliance that heats and stores or delivers hot water, consisting of a tank or heat exchanger, a heat source, controls, and safety devices such as a relief valve.

A safety device on a water heater that opens to release water if temperature or pressure exceeds its rating, preventing tank rupture; its discharge must terminate safely and visibly.

A watertight pan placed under a water heater in certain locations to catch leaks, piped to an approved indirect drain so any discharge is visible and does not damage the building.

The system of pipe, tubing, and fittings that delivers natural gas or propane from the meter or tank to appliances, sized by allowable pressure drop and installed to leak-test requirements.

A dirt-leg fitting arrangement installed at the appliance connection to catch scale and debris before it reaches the gas controls, typically a tee with a capped nipple below the inlet.

A manual valve installed in the gas supply line at or near each appliance so the appliance can be isolated for service; must be accessible and clearly indicate open and closed positions.

The air supplied to a gas appliance for burning fuel, provided by outdoor air openings, indoor air from a sufficiently large space, or a combination, sized by the appliance input rating.

The pipe that carries flue gases from an appliance's draft hood or flue collar to the chimney or vent, installed with rise and limited length and elbows per code.

Reverse flow of flue gases into a space caused by inadequate draft, negative pressure, or blocked venting; a serious carbon monoxide hazard detected by spillage or draft testing.

The stage of work where pipes, fittings, and supports are installed in walls, floors, and ceilings before fixtures and finished surfaces are placed; subject to inspection before covering.

Written authorization from the authority having jurisdiction to install, alter, or repair plumbing work; issued before work begins and required for most projects beyond minor repairs.

The official or agency responsible for enforcing the plumbing code, issuing permits, conducting inspections, and approving materials, methods, and variances within its area.

The AHJ's on-site review of permitted work at required stages, such as rough-in, water test, gas pressure test, and final, to confirm compliance before the work is covered or used.

The speed of water or gas flow through a pipe, usually in feet per second; excessive velocity causes noise, erosion, and high friction loss, so pipe sizes are chosen to keep it in range.

A banging noise and pressure surge caused when flowing water is stopped suddenly by a quick-closing valve; controlled with air chambers, arrestors, or slower-closing valves.