MD Plumber key terms

The depth of water held in a plumbing fixture's trap, measured from the crown weir to the top of the dip, that blocks sewer gas from entering the building.

The point on the outlet side of a trap where the top of the waterway meets the bottom of the trap dip, marking where the trap seal begins.

A water-retaining fitting installed directly below a fixture drain that creates a seal against sewer gas while allowing wastewater to pass through.

A vertical pipe that extends above the roof to admit air into the drainage system and relieve pressure so trap seals are not siphoned out.

The open end of a vent pipe where it terminates outdoors above the roof, admitting air and releasing gases safely above occupied space.

The upward extension of a soil or waste stack above the highest fixture connection, serving as the vent for that stack.

A vertical pipe that carries sewage containing fecal matter from water closets downward to the building drain.

A vertical pipe that conveys liquid waste from fixtures other than water closets, such as sinks, lavatories, and tubs, down to the building drain.

The lowest horizontal pipe in a building's drainage system that receives soil and waste from stacks and conveys it to the building sewer.

The pipe outside the building foundation that carries sewage from the building drain to a public sewer or private disposal system.

A device installed in a drain line that closes automatically to prevent sewage from flowing backward into the building during a sewer surcharge.

An assembly installed in a water supply line that stops contaminated water from reversing flow into the potable supply.

An unobstructed vertical space between a water outlet and the flood level of a fixture or receptacle, providing the highest form of backflow protection.

The edge of a fixture or receptacle over which water would overflow onto the floor, used as the reference point for air gaps and vacuum breakers.

A device that admits air into a piping system when internal pressure drops, breaking a siphon that could draw contaminants backward.

A loud banging or knocking in pipes caused by the sudden stop of water flow and the resulting shock wave, often controlled by an arrestor.

A device containing a trapped air chamber or piston that absorbs the pressure surge created when a valve closes quickly.

A regulating valve that lowers incoming water pressure to a safe, consistent level for the building's piping and fixtures.

The increase in water volume as it is heated, which raises pressure in a closed system and requires a control device such as an expansion tank.

An appliance that heats and stores potable water for domestic use, equipped with a temperature and pressure relief valve for safety.

A temperature and pressure relief valve that opens automatically to discharge water when a water heater exceeds safe temperature or pressure limits.

The pipe that carries relief valve discharge safely to a drain or outdoors, installed to drain by gravity without traps or reduced size.

The total measured length of a pipe run including fittings and changes of direction, used to size pipe and determine friction loss.

The pressure lost as water flows through pipe and fittings due to resistance, increasing with flow rate, pipe length, and roughness.

The pressure exerted by water at rest in a system, measured in psi and determined largely by the height of the water column.

A standardized value expressing the probable drainage load or water demand of a fixture, used to size pipes and vents.

The total fixture units discharging into a given section of drainage piping, used to determine the required pipe diameter and slope.

The downward pitch of a horizontal drain, expressed as fall per unit of run, that lets wastewater flow by gravity while carrying solids.

An accessible fitting with a removable plug that allows a drain line to be rodded or inspected for blockages.

The portion of a fixture drain between the trap weir and the vent connection, sized and limited in length to protect the trap seal.

A vent pipe that also serves as a drain for fixtures on a higher floor, permitted only under specific code conditions.

The pipe that carries potable water from the public main or private source to the building's water distribution system.

A device that measures the volume of water delivered to a building, typically installed on the service line with required valves and clearances.

Water that is safe for human consumption and meets health standards, protected from contamination throughout the distribution system.

A pump installed in a pit that removes accumulated groundwater or drainage from a basement or crawl space.

The Maryland credential that authorizes a person to contract for plumbing work and to supervise journeypersons and apprentices.

A Maryland credential allowing a plumber to perform plumbing work under the direction of a licensed master plumber.

A person learning the trade under supervision while accumulating the required work hours toward journeyperson licensure.

Official authorization from the local authority to perform specified plumbing work, subject to inspection and code compliance.

The inspection of piping, vents, and connections completed before fixtures and walls are closed up, verifying code compliance.

The last inspection confirming that fixtures, equipment, and systems are installed, tested, and functioning according to the approved plans and code.

The local official or agency empowered to enforce the plumbing code, issue permits, and approve or reject installations.