MT Journeyman Plumber key terms

A dimensionless measure of the load a plumbing fixture places on the drainage system, combining its discharge rate and the time it takes to drain. Drain and vent pipe sizes are selected from tables based on the total fixture units served.

The fixture unit value assigned to a fixture for sizing the sanitary drainage system, derived from its drain outlet size and trap arm characteristics. Values appear in the UPC fixture unit tables and vary by fixture type and occupancy.

The fixture unit value assigned to a fixture for sizing water distribution piping, reflecting its probable demand in gallons per minute and the diversity of simultaneous use. Total WSFU, not DFU, drives water pipe sizing.

The portion of a drainage pipe between a fixture trap and the vent connection or stack. Its length and fall are limited by the trap arm size, and exceeding those limits requires a relief vent or reconfiguration.

A water-seal device installed directly below or at the outlet of a fixture that prevents sewer gas from entering the building. It must maintain a specified water seal depth and be accessible for cleaning.

The vertical depth of water retained in a fixture trap that blocks sewer gas. The UPC sets minimum and maximum seal depths, and the seal is measured from the trap weir to the dip.

The crown or highest point on the outlet side of a trap's dip that establishes the water level in the trap and sets the elevation from which the trap seal is measured. The vent must connect above the weir.

The unobstructed vertical distance through free air between a potable water outlet and the flood-level rim of a receptor. It is the highest form of backflow protection and is required for certain fixtures such as sinks and sterilizers.

An assembly such as a reduced-pressure principle assembly, double check valve, or vacuum breaker that prevents reverse flow of contaminated water into the potable supply. Selection depends on the degree of hazard and requires periodic testing.

Any actual or potential link between the potable water system and a source of contamination or pollution. The UPC requires cross-connections to be eliminated or protected by an approved backflow prevention method.

A backflow prevention device that admits air into piping to break a siphon when pressure drops, protecting the potable supply from a submerged inlet. Common types include atmospheric, pressure, and hose-connection breakers.

The elevation at which water will overflow the edge of a fixture, receptor, or receptacle. It is the reference point for setting air gaps and for determining the required height of backflow protection devices.

A drainage connection in which wastewater discharges into a receptor through an air gap rather than a direct pipe connection, protecting the fixture from backup. Examples include food-handling sinks and sterilizers.

The lowest piping of a drainage system that receives the discharge from soil, waste, and other drainage pipes inside the building and conveys it to the building sewer, ending outside the foundation wall.

The pipe carrying sewage from the building drain to the public sewer, private sewage disposal system, or other point of disposal. It begins outside the building foundation and is subject to separate slope and material rules.

A vertical drainage pipe that carries the discharge of water closets and may also receive other fixtures. It extends from the building drain upward and must be properly vented to protect trap seals.

A vertical pipe installed to provide circulation of air to and from the drainage system, extending above the roof. It serves fixtures on multiple floors and must be sized according to the fixtures it vents.

The extension of a soil or waste stack above the highest horizontal drain connected to it, terminating outdoors. It vents the stack itself and is distinguished from a separate vent stack serving fixtures.

The fitting or pipe connecting a vent to a drain or to another vent. It must be located above the trap weir and within the allowable distance from the trap to prevent siphonage.

A drainage pipe that connects fixtures to a soil or waste stack or building drain and runs at a slope of less than 45 degrees from horizontal. Its size and length are governed by fixture unit tables.

The downward pitch of a horizontal drainage pipe expressed in inches per foot. The UPC prescribes minimum slopes by pipe size, and insufficient slope causes solids to settle while excessive slope allows liquid to outrun solids.

An accessible fitting with a removable plug or cover that provides access for clearing blockages in a drainage line. The UPC specifies required locations, spacing, and sizes for cleanouts on building drains and stacks.

The total measured length of a pipe run along its centerline, including all fittings and changes in direction, used to size water distribution piping and determine pressure loss from friction.

The loss of pressure in flowing water caused by resistance along pipe walls and through fittings. It is added to elevation and fixture pressure requirements when sizing water piping and selecting pumps or regulators.

A device that lowers incoming water pressure to a safe, usable level for the building's distribution system. It is required where supply pressure exceeds the UPC limit and must be accessible for adjustment and repair.

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 control this pressure to protect piping and fixtures.

An appliance that heats potable water for domestic use. The UPC regulates its installation, including temperature and pressure relief valves, discharge piping, seismic or support requirements, and venting of fuel-fired units.

A safety device on a water heater that opens to discharge water if temperature or pressure exceeds safe limits. Its discharge pipe must be full size, gravity-drained, and terminate in a safe, visible location.

A toilet fixture that receives human waste and discharges it through a trap to the drainage system. The UPC sets water consumption limits, rough-in dimensions, and fixture unit values for water closets.

A valve that delivers a measured flush to a fixture using line pressure rather than a tank. It requires a minimum supply pressure and flow rate and must be protected against backflow and cross-connection.

Requirements ensuring plumbing fixtures and controls can be used by people with disabilities, covering clear floor space, grab bars, mounting heights, and operable controls. The UPC references accessibility standards for fixture installation.

A wash basin fixture used for personal hygiene. The UPC regulates its drain size, trap, overflow, and the required air gap or backflow protection for the faucet outlet above the flood-level rim.

Piping that conveys natural gas or propane to appliances. Installation follows the UPC's fuel gas provisions and requires approved materials, pressure testing, and bonding, with work often limited to licensed plumbers.

Piping systems conveying oxygen, nitrous oxide, medical air, or vacuum in health care facilities. Installation requires specialized qualifications, brazing procedures, and verification testing beyond standard plumbing licensing.

A test in which a piping system is filled with water or air and pressurized to a specified level to detect leaks before being placed in service. The UPC prescribes test pressures and durations for drainage and water systems.

The state board responsible for licensing journeyman and master plumbers and registering apprentices in Montana. It adopts rules, administers examinations, and handles complaints and disciplinary actions under state law.

A Montana credential allowing the holder to perform plumbing work under the supervision of a master plumber or licensed contractor. It requires documented experience, passage of an examination, and continuing education for renewal.

The highest Montana plumbing credential, permitting the holder to supervise plumbing work, obtain permits, and operate a plumbing business. It generally requires journeyman experience plus examination and continuing education.

A Montana requirement for businesses offering plumbing services, ensuring the firm has a licensed master plumber responsible for its work and carries required insurance. Registration is separate from individual licensing.

A person learning the trade under supervision while accumulating the hours required for journeyman licensure. Apprentices must be registered with the Montana Board of Plumbers and work under a licensed plumber.

An authorization issued by the local authority to install or alter plumbing work, allowing inspection at required stages. Working without a required permit can result in penalties and is a common licensing-law exam topic in Montana.