Master Plumber flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Fixture unit

A dimensionless measure of the probable load a fixture places on a drainage or water supply system; one drainage fixture unit equals about 1 cubic foot per minute, or 7.48 gpm.

Authority having jurisdiction

The organization or official responsible for enforcing the plumbing code, approving alternate materials and methods, issuing permits, and performing the required inspections.

Code as minimum standard

Plumbing codes set minimum requirements for health and safety, so a code-compliant installation is the floor rather than the ceiling, and stricter local amendments control.

Residual pressure

Residual pressure is the pressure remaining at a fixture or outlet while water is flowing; adequate residual pressure ensures fixtures function without being starved by undersized piping.

Pressure-reducing valve

A regulating device installed downstream of the meter when static supply pressure exceeds about 80 psi, protecting fixtures and piping from excess pressure and water hammer damage.

Static versus flow pressure

Static pressure is measured with no water moving; flow or residual pressure is measured while water moves. The difference reflects friction loss in the meter and piping.

Water hammer arrestor

A prefabricated device containing a trapped air or gas cushion, installed near quick-closing valves to absorb the pressure surge created when flow stops abruptly.

Trap seal depth

The trap seal is the water held in a fixture trap that blocks sewer gas; codes require a seal at least 2 inches and no more than 4 inches deep.

Drainage slope for small pipe

Horizontal drainage pipe 2 inches and smaller is typically installed at 1/4 inch per foot, while 3-inch through 6-inch pipe uses 1/8 inch per foot.

Vent terminal height

A vent stack must terminate outdoors, typically at least 6 inches above the roof surface and far enough from windows, doors, and air intakes to prevent odor entry.

Cleanout location

Cleanouts are required at the base of each stack, at the building drain, at intervals not exceeding 100 feet of horizontal run, and at turns greater than 45 degrees.

Wet vent

A wet vent is a drain serving one or more fixtures that also vents a downstream fixture, permitted only within the size and length limits set by code.

Water closet flow rate

Federal standards limit new tank-type water closets to 1.6 gallons per flush, and many jurisdictions and the WaterSense program require 1.28 gallons per flush or less.

Showerhead flow limit

Showerheads are limited to 2.5 gallons per minute at 80 psi test pressure; multi-head installations must also satisfy aggregate flow and local code requirements.

Fixture trap requirement

Every fixture that discharges sewage or liquid waste must be trapped, except fixtures with an integral trap, and each trap must be vented unless an approved exception applies.

TP relief valve

The temperature-and-pressure relief valve protects a water heater from over-pressure or overheating; its discharge pipe must remain full size, drain by gravity, and terminate safely.

Water heater drain pan

A drain pan is required where a water heater is installed in a location where leakage could cause damage; the pan must drain or be piped to a safe disposal point.

Thermal expansion tank

On a closed system with a backflow preventer or check valve, an expansion tank absorbs the volume increase as water heats, preventing relief valve discharge and pressure damage.

Copper water tube types

Copper water tube comes in types K, L, and M, with K the thickest wall, L intermediate, and M thinnest; type M is restricted in some concealed or underground uses.

Dielectric union

A dielectric union separates dissimilar metals such as copper and steel with a nonmetallic insulator, preventing galvanic corrosion at the threaded connection between them.

PEX expansion fitting

With PEX-A tubing, an expansion tool stretches the pipe, an expanded fitting is inserted, and the pipe shrinks back over the fitting to form a permanent seal without crimp rings.

Solvent cement joint

A solvent-cemented plastic joint requires cleaning, applying primer where required and cement to both surfaces, assembling with a quarter turn, and holding until the joint sets.

Sediment trap

A sediment trap, or drip leg, is a capped vertical extension at the appliance gas inlet that catches dirt and pipe scale before it can reach the gas valve.

Unconfined space combustion air

An indoor space is treated as unconfined when it provides roughly 50 cubic feet of volume per 1,000 Btu/hr of appliance input and is not of tight construction.

CSST bonding

Corrugated stainless steel tubing must be bonded to the grounding electrode system with a listed clamp and conductor, commonly 6 AWG copper, to reduce damage from lightning arcs.

Air gap

An air gap is the unobstructed vertical distance between a potable water outlet and the flood level rim of the receiving fixture, typically twice the pipe diameter and at least 1 inch.

Reduced pressure zone assembly

An RPZ is a testable backflow assembly for high-hazard connections, using two independent check valves and a differential relief valve that discharges if flow reverses.

Atmospheric vacuum breaker

An atmospheric vacuum breaker must be installed downstream of the last control valve, at least 6 inches above the highest downstream outlet, and cannot be under continuous pressure.

Developed length

Developed length is the total measured piping length from the source to the most remote outlet, including allowances for fittings, and is used to size water and gas piping.

Riser diagram

A riser diagram is a single-line isometric drawing showing the arrangement, sizes, and connections of water, drain, waste, and vent piping through the building floors.

DWV hydrostatic test

A DWV system is commonly tested by filling it with water to a 10-foot head for 15 minutes, or by an approved air test where permitted, with all joints leak-free.

Potable line disinfection

New or repaired potable water piping is disinfected, commonly with a chlorine solution of about 50 ppm for 24 hours, then flushed and sampled for satisfactory bacteriological results.