GA Plumber key terms

The unobstructed vertical distance between the lowest point of a water supply outlet and the flood-level rim of the receiving fixture or vessel. It is the most reliable form of backflow protection because no mechanical parts can fail.

Any actual or potential link between the potable water system and a source of nonpotable water or other contaminant. Codes require it to be eliminated or protected by an approved backflow assembly.

A testable assembly with two independently acting check valves and a differential pressure relief valve located between them. It protects against both backsiphonage and backpressure and must be tested after installation and annually.

A device that admits air into a piping system when internal pressure drops below atmospheric, breaking a siphon. Atmospheric and pressure types are common, and hose-bibb vacuum breakers protect outside sillcocks.

Water that is safe for human consumption and meets health standards for bacteriological, chemical, and physical quality. Codes prohibit connecting nonpotable sources to the potable distribution system.

A dimensionless measure of the probable demand a fixture places on the water distribution system, accounting for flow rate and duration of use. Fixture units are totaled and converted to pipe size using code tables.

A device that lowers incoming water pressure to a stable, safe downstream value, typically about 50 to 60 psi. It protects fixtures and appliances where street pressure exceeds code limits.

A sealed chamber containing a cushion of air or a piston that absorbs the pressure surge created when a valve closes quickly. It is installed near the fixture or quick-closing valve causing the shock.

A measure of the rate at which a fixture discharges waste into the drainage system, used to size drains, branches, and stacks. Values are assigned by code based on fixture type and use.

The lowest piping of a drainage system that receives waste from soil and waste stacks inside the building and conveys it to the building sewer, typically ending about five feet outside the wall.

The pipe carrying sewage from the building drain to the public sewer, private treatment system, or other point of disposal. It begins where the building drain ends.

A vertical pipe that conveys sewage, meaning waste from water closets and similar fixtures, from fixtures down to the building drain. It usually extends through the roof as a vent.

The extension of a soil or waste stack above the highest fixture connection, open to the atmosphere. It vents the stack and is often continued through the roof.

A vertical vent pipe that provides air to a drainage stack or branch to protect trap seals. It connects the drainage system to outdoor air and may serve several branch vents.

A one-way valve that opens to admit air into a drainage system when pressure drops and closes to keep sewer gas from escaping. Code limits where and how many may be used.

The water held in the dip of a trap that blocks sewer gas from entering the building. Codes require a depth of 2 to 4 inches and protection from evaporation, siphonage, and backpressure.

The pipe section between a fixture trap and the point where it connects to a vented drain. Its length and fall are limited so the trap seal is not siphoned.

A device or arrangement that automatically adds water to a floor drain or other infrequently used trap so the seal does not evaporate. Common types are pressure-drop and electronic primers.

An accessible fitting with a removable plug or cover that allows a drain or sewer to be rodded and cleared of blockages. Codes specify its size, spacing, and accessibility.

The downward pitch of horizontal drainage pipe, expressed in inches per foot. Common minimums are 1/4 inch per foot for pipe 2 1/2 inches and smaller and 1/8 inch per foot for larger pipe.

The total measured length of pipe along its centerline, including fittings and changes of direction, between two points. It is used in drainage, vent, and gas piping sizing calculations.

A tank that slows wastewater so fats, oils, and grease float and are retained while clearer water flows out. It must be sized to the fixtures served and maintained by periodic pumping.

Waste that discharges into a receptor or fixture through an air gap or air break instead of connecting directly to the drainage system. It protects food, medical, and potable equipment from contamination.

A piping arrangement in which a drain discharges into a receptor below the flood-level rim of the fixture it drains, leaving a physical gap. It prevents backflow by separation.

A vertical or horizontal pipe that carries rainwater from roof drains, gutters, or scuppers to the storm drainage system. Leaders are sized from roof area and rainfall intensity.

Piping and appurtenances that collect and convey rainwater and surface water to a point of disposal. It must be kept separate from sanitary drainage where separate sewers are required.

A safety device on a water heater that opens when temperature or pressure exceeds its rating, releasing hot water and steam. It must be piped to a safe discharge point by gravity.

A closed tank with a pre-charged air chamber that absorbs the extra volume of water as it heats in a closed system. It prevents excessive pressure and T&P valve discharge.

A sacrificial metal rod, usually magnesium or aluminum, installed in a tank-type water heater to corrode before the steel tank does. It should be inspected and replaced periodically.

A capped vertical pipe leg installed at the lowest point of a gas line near an appliance to collect dirt, scale, and condensate before they reach the controls. Codes require it for most appliances.

A test in which gas piping is filled with air or inert gas and monitored with a gauge for a set period to prove it is leak-free. Test pressure and duration follow code requirements.

A test that fills a drainage or water piping system with water and holds it under pressure, or full, to reveal leaks before the system is covered or placed in service.

A test that forces smoke into the drainage and vent system to reveal leaks and improper connections. It verifies that sewer gas cannot escape into a building.

A three-dimensional style of plumbing drawing in which vertical, horizontal, and depth runs are shown at fixed angles so pipe routing can be read from a single view.

The abbreviation for drain, waste, and vent: the portion of a plumbing system that removes wastewater and equalizes pressure through vents. DWV pipe is not used for pressurized supply.

The stage of construction when piping, drains, and vents are installed inside walls and floors before fixtures and finished surfaces are set. It is inspected before being covered.

A receptor set flush with the floor that receives surface water and discharges through a trap into the drainage system. It usually includes a strainer and may have a trap primer.

A valve installed in a drainage line that closes automatically when flow reverses, preventing sewage from backing up into a building during a sewer surcharge.