OH Journeyman Plumber key terms

An unobstructed vertical distance between the lowest opening of a water supply outlet and the flood-level rim of the fixture it serves. It provides the highest level of backflow protection.

A device installed in a water supply line that stops contaminated water from reversing direction and entering the potable supply. Common types include reduced-pressure zone assemblies and double check valves.

Any actual or potential link between a potable water system and a source of contamination or pollution. Eliminating cross-connections is the core purpose of backflow protection requirements.

A backflow prevention device that opens to atmosphere when supply pressure drops, breaking a siphon. Atmospheric and pressure-type versions are common on hose bibbs and flush valves.

A banging or pounding noise and pressure surge caused by the sudden stop of water flow in a pipe. Arrestors or air chambers absorb the shock and protect piping and fixtures.

A manufactured device with a sealed air or gas chamber installed near a quick-closing valve to absorb pressure surges. Preferred over simple air chambers because it does not become waterlogged.

The total measured length of pipe along its centerline from the source to the farthest outlet, including all fittings and changes in direction. Used to size pipe and determine pressure loss.

The friction loss of a fitting or valve expressed as an added length of straight pipe of the same diameter. Added to developed length when calculating total pressure loss.

Pressure lost as water moves through pipe, fittings, and valves due to resistance. Increases with flow rate, pipe roughness, and length, and decreases with larger pipe diameter.

The pressure exerted by water at rest, equal to roughly 0.433 psi per foot of vertical height. It is the baseline used when evaluating supply pressure at fixtures.

The pressure remaining in a water system while water is flowing. It is lower than static pressure because of friction and elevation losses along the path.

A device that lowers incoming water pressure to a safe, usable level for the building. It protects fixtures and appliances from excess pressure and is often required above a set threshold.

A unit of measure expressing the load a plumbing fixture places on the drainage or water supply system. Values are assigned by code based on fixture type and flow characteristics.

A value assigned to a fixture representing its probable discharge rate into the drainage system. Used to size building drains, branches, and stacks.

A fitting that holds a water seal to prevent sewer gas from entering a building. Each fixture must have a trap unless specifically exempted by code.

The depth of water retained in a trap, measured between the crown weir and the dip of the trap. It must be maintained to block sewer gas.

The pipe section connecting a fixture trap to the drain or branch it discharges into. Its length and slope are limited by code to prevent self-siphoning.

A pipe or opening that lets air into the drainage system and allows sewer gas to escape outdoors. Vents protect trap seals from siphonage and back pressure.

A vertical vent pipe that provides air to a soil or waste stack and carries gases to the outdoors above the roof. It is separate from the stack it serves.

A vertical pipe that carries wastewater or vent air through a building. Soil stacks carry sewage, waste stacks carry other wastewater, and vent stacks carry air.

The extension of a soil or waste stack above the highest horizontal drain connected to it, terminating outdoors. It vents the stack itself.

A one-way valve that admits air into a drainage system when pressure drops but seals to prevent sewer gas from escaping. Allowed only in limited applications by code.

The fall of a horizontal drain pipe per unit of length, usually expressed in inches per foot. Correct slope keeps solids moving and prevents clogs.

The lowest horizontal piping of a drainage system that receives waste from inside the building and conveys it to the building sewer. It ends at the building wall.

The pipe that carries sewage from the building drain to the public sewer or private disposal system. It begins outside the building wall.

An accessible opening with a removable cap that allows a drain line to be cleared of blockages. Codes require them at specified intervals and at changes in direction.

The top edge of a fixture over which water would spill onto the floor. It is the reference point for setting air gaps and backflow protection.

A toilet fixture that receives human waste and discharges it through a trap to the drainage system. It is available in gravity, pressure-assisted, and flushometer types.

A valve that uses supply line pressure to deliver a measured flush volume to a fixture. It requires adequate pressure and flow and needs backflow protection.

The increase in water volume as it is heated, which raises pressure in a closed system. A thermal expansion tank absorbs this volume and protects the system.

An appliance that heats potable water for domestic use. Installation requires temperature and pressure relief, proper venting, and seismic or expansion provisions where required.

A safety device on a water heater that opens to release excess temperature or pressure. It must be piped to a safe discharge point and never capped or blocked.

A connection made by melting filler metal between copper tube and a fitting. Proper cleaning, flux, and heat produce a leak-free joint; lead-free solder is required for potable water.

A mechanical fitting joined to pipe by crimping with a tool that compresses an O-ring seal. It avoids open flame and is common in copper and PEX systems.

Cross-linked polyethylene tubing used for water supply. It is flexible, joined with mechanical or barb fittings, and must be protected from sunlight and physical damage.

Metal tubing available in types K, L, and M with different wall thicknesses. Type L is common for interior water supply; type M is thinner and used in some drain applications.

Gear worn to reduce injury risk on the job, such as safety glasses, gloves, hearing protection, and respirators. Selection depends on the task and hazard present.

A space large enough to enter, with limited entry or exit, not designed for continuous occupancy. Entry may require testing, ventilation, and a permit.

A procedure that isolates energy sources and applies locks and tags before work begins. It prevents accidental startup or release of stored energy during maintenance.

Official authorization to perform plumbing work, issued by the local authority having jurisdiction. It typically requires plan review and inspection at defined stages.

The official or agency responsible for enforcing the plumbing code in a given area. They interpret code, issue permits, and conduct inspections.

A required on-site review by the authority having jurisdiction at specified stages of work, such as rough-in and final. Approval is needed before covering work or occupying a building.

The stage of plumbing work completed before walls and floors are closed, including pipe installation and fixture stub-outs. It must be inspected before concealment.

A three-dimensional style drawing showing piping runs along angled axes. Plumbers use it to plan and communicate layout of water and drain lines.