NJ Master Plumber key terms

The unobstructed vertical distance through free atmosphere between the lowest opening of a water supply outlet and the flood-level rim of the fixture or receptacle it serves. It is the most reliable form of backflow protection.

The unwanted reversal of normal water flow in a potable water system, caused by backpressure or backsiphonage. It can carry contaminants into drinking water and must be prevented by an approved device or arrangement.

Backflow produced by a negative or reduced pressure in the supply piping, which draws nonpotable fluid into the potable system through an unprotected connection. A common cause is a main break or heavy demand such as firefighting.

Backflow caused when the pressure on the downstream side of a connection exceeds the supply pressure, pushing nonpotable fluid into the potable system. Pumps, boilers, and elevated tanks commonly create this condition.

Any actual or potential physical link between a potable water supply and a source of contamination or pollution. Such connections must be eliminated or protected by an approved backflow preventer.

A testable backflow preventer with two independently acting check valves and a hydraulically operated differential relief valve between them. It protects against both backpressure and backsiphonage at high hazard and requires annual testing.

A device that admits air into piping to break a vacuum and prevent backsiphonage. Atmospheric and pressure-type styles protect hose bibs, flush valves, and other outlets where an air gap cannot be maintained.

The edge of the receptacle from which water would overflow if the drain were blocked. It establishes the reference point for air gaps and for setting fixture and vacuum breaker heights.

The vertical depth of liquid retained in a trap that blocks sewer gas from entering a building. It is measured between the crown weir and the top of the trap dip and must be maintained within code limits.

The point on the outlet side of a trap where liquid first begins to spill over and flow downstream. It marks the upper limit of the trap seal depth and the start of the trap arm.

The pipe section between a trap's outlet and its connection to a vent or drain stack. Its length and slope are limited so the trap is not siphoned and the fixture drains properly.

A trap designed with a seal deeper than the standard minimum, used where evaporation or pressure fluctuation threatens to break the seal. Excessively deep seals can slow drainage and collect waste.

A receptacle installed in a drainage line to separate fats, oils, and grease from wastewater before it enters the sewer. It retains floating grease and requires periodic pumping and maintenance by the owner.

A smaller grease-removal device, typically installed under a sink or near fixtures, that intercepts kitchen waste before it reaches the drainage system. It must be accessible for cleaning and sized to fixture flow.

A dimensionless measure of the probable discharge load a fixture places on the drainage system, based on its flow rate and use. Fixture units are summed to size branches, stacks, and building drains.

A dimensionless measure of the probable demand a fixture places on the water distribution system, accounting for flow rate and frequency of use. Values are totaled to size supply piping and meters.

The lowest piping of a drainage system that receives waste from inside the building and conveys it to the building sewer. It extends to a point outside the building wall, where the building sewer begins.

The piping that carries sewage from the building drain to the public sewer or private disposal system. It begins outside the building wall and is typically governed by separate municipal requirements.

The drain pipe that connects one or more fixtures to a stack, branch, or building drain. Its size is determined by the total fixture units served and the slope of the pipe.

An accessible opening with a removable cap or plug that allows a drain to be rodded or inspected. Required at the base of stacks, at changes in direction, and at intervals along horizontal runs.

The fall of a horizontal drain per unit of length, expressed as a percentage or in inches per foot. Proper slope maintains scouring velocity while preventing solids from being left behind.

A vertical pipe that carries drainage or venting between floors. A soil stack handles water closets, a waste stack handles other fixtures, and a vent stack serves the venting system.

A vertical vent pipe that provides air to a drainage system and relieves pressure in the stacks. It extends upward and terminates outdoors above the roof.

The open end of a vent pipe that extends above the roof to admit air and release gases. Its height, location, and distance from windows and air intakes are regulated to protect occupants.

A one-way valve that opens to admit air into a drainage system when pressure drops and closes to prevent sewer gas escape. It is permitted only in specific locations and must be accessible.

A vent that also serves as a drain for fixtures above or downstream of the fixtures it vents. Its use is limited by code because simultaneous drainage and venting can affect performance.

The total measured length of pipe and fittings in a water distribution run, including equivalent lengths for elbows, tees, and valves. It is used with fixture unit totals to determine pipe size.

A device that lowers incoming water pressure to a safe, usable level for the building's piping and fixtures. It protects against excess pressure and is often paired with a thermal expansion tank.

The increase in water volume as it is heated, which raises pressure in a closed plumbing system. A thermal expansion tank or other approved means must absorb this volume to protect piping and fixtures.

A safety device that opens to discharge water if temperature or pressure in a water heater exceeds safe limits. It must be piped to a safe discharge point and never capped or plugged.

An appliance that heats and stores potable water for domestic use, typically with a tank and thermostat controls. Installation requires seismic strapping, venting, relief valves, and clearance from combustibles.

The system of pipe, tubing, and fittings that delivers natural gas or propane from the meter or tank to appliances. Materials, sizing, support, and leak testing are governed by fuel gas code provisions.

A dirt pocket installed at the gas inlet of an appliance to collect debris and moisture before it reaches the controls. It is typically a capped tee below the appliance connection.

A flexible or semi-rigid connector that links gas piping to a movable or fixed appliance. It must be listed, sized for the appliance input, protected from damage, and not concealed in walls.

The piping and appurtenances that collect and convey rainwater, surface water, and other clear water to a point of disposal. It is kept separate from sanitary drainage to prevent overload and contamination.

A fitting that collects rainwater from a flat or low-slope roof and discharges it into the storm drainage system. Its size and the number required depend on roof area and design rainfall intensity.

The credential that authorizes a person to design and install plumbing systems, obtain permits, and supervise plumbing work in a jurisdiction. Requirements typically include documented experience and passing a licensing examination.

The official authorization issued by a code authority before regulated plumbing work begins. Permits allow inspections, establish legal responsibility for the work, and must be obtained before concealed work is covered.

The code official's review of plumbing work at required stages, such as rough-in and final, to confirm compliance. Concealed work must be inspected before it is covered, and approval is needed before use.

The stage of plumbing installation completed before walls, floors, and fixtures are finished, including piping, vents, and rough connections. It is inspected before concealment to verify code compliance.

A licensed plumber qualified to perform plumbing work under the supervision of a master plumber. Licensing usually requires documented apprenticeship hours and passage of a trade examination.