AL Plumber cheat sheet

A plumbing permit is required before new installation, alteration, replacement, or repair unless the code or authority having jurisdiction exempts the work.

Approved materials and fixtures must be installed according to their listing; used materials require approval before reuse.

Work must remain accessible for inspection, and concealment before inspection requires approval.

The code official has authority to issue stop-work orders, require tests, and approve or reject installations.

A fixture unit is a measure of the load-producing effect of a fixture on the drainage system.

Developed length is measured along the pipe centerline including fittings and changes in direction.

An air gap is the unobstructed vertical distance between a supply outlet and the flood-level rim.

A cross-connection is any connection between potable water and a nonpotable source.

1 psi equals 2.31 feet of water column; pressure in psi = head in feet × 0.433.

Drainage slope as a percent = inches per foot ÷ 12 × 100; 1/4 inch per foot is about 2.08%.

For a 45-degree offset, travel = offset × 1.414.

Decimal feet = inches ÷ 12; 6 inches = 0.5 foot.

Volume of a cylinder = π × radius² × length; 1 gallon = 231 cubic inches.

On an isometric drawing, vertical lines are vertical and horizontal lines are drawn at 30 degrees from horizontal.

Scale 1/4 inch = 1 foot means 1/4 inch on the drawing represents 12 inches actual.

Total drainage fixture units are added arithmetically and then converted with code tables for pipe sizing.

Standard drainage fixture units: water closet 3, lavatory 1, bathtub 2, shower 2, kitchen sink 2.

Water closet clearance: at least 15 inches from centerline to sidewall and 21 inches clear in front.

Federal maximum showerhead flow is 2.5 gpm at 80 psi.

Water closet maximum flush volume is 1.6 gallons per flush; urinal maximum is 1.0 gallon per flush.

Floor drains subject to trap evaporation require a trap primer.

Food-handling equipment and sterilizers use indirect waste with an air gap or air break.

Accessible lavatory rim height is generally 34 inches maximum above the finished floor.

Fixture supply stops are required at each fixture except where the code permits otherwise.

Minimum flowing pressure: 8 psi at flush tanks and general fixtures; 15 psi at flushometer valves.

A pressure-reducing valve is required where static pressure exceeds 80 psi.

Closed potable water systems with a water heater require thermal expansion control.

Water hammer arrestors are installed near quick-closing valves to absorb pressure surges.

Water distribution pipe sizing uses fixture units, developed length, and allowable pressure loss.

Hot and cold water pipe must be protected from freezing; buried service is installed below frost depth.

Potable water lines must be separated from nonpotable lines and cannot be directly connected to a nonpotable source.

A water service pipe cannot be installed in the same trench as a sewer unless separation and materials meet code.

Slope: 2.5 inches and smaller = 1/4 inch per foot; 3 to 6 inches = 1/8 inch per foot; 8 inches and larger = 1/16 inch per foot.

Drainage pipe size must not decrease in the direction of flow.

Cleanouts are required at the base of each stack, every 100 feet of horizontal drain, and at changes greater than 45 degrees.

A building drain extends from inside the building to 30 inches outside the building wall.

A building sewer begins at the building drain and runs to the public sewer or private disposal system.

Backwater valves are required for fixtures below the street or sewer level where backup is possible.

Trap arms must be vented within the code-listed distance for the pipe size.

Horizontal drainage pipe receiving a vertical stack requires approved fittings at the transition.

Every fixture trap must be vented unless the code lists a specific exception.

Vent pipe must rise at least 6 inches above the fixture flood-level rim before any horizontal offset.

Vent terminals must extend at least 6 inches above the roof and be located away from windows, doors, and air intakes.

Vent pipe cannot be smaller than 1.25 inches and must meet the code size table.

A wet vent serves as both a drain and a vent only for code-listed fixture combinations.

An air admittance valve requires accessibility and must be listed for the application.

A vent stack and stack vent connect the drainage stack to the vent system.

A circuit vent vents a row of fixtures through a common vent line.

Trap seal depth must be at least 2 inches and not more than 4 inches.

Each fixture requires an individual trap except where the code permits common or combination traps.

S-traps, crown vents, and double trapping are prohibited.

Grease interceptors are required for commercial kitchen waste and must be sized per code.

Sand and oil interceptors are required for garages and similar facilities where these wastes are discharged.

Indirect waste receptors receive waste through an air gap or air break.

Trap primers maintain trap seals for floor drains subject to evaporation.

Interceptors require accessible cleanouts for maintenance.

A temperature and pressure relief valve is required on each water heater.

The T&P relief valve opens at about 210 degrees Fahrenheit or 150 psi and discharges by gravity, full size, without a valve.

The relief discharge must terminate at least 6 inches above the floor or to an approved drain.

A closed potable water system with a water heater requires a thermal expansion tank.

A drain pan is required where leakage could cause damage; its drain goes to an indirect waste.

Gas water heaters require combustion air and proper flue venting.

The relief valve opening must not be capped, plugged, or reduced.

Water heater seismic strapping is required where the code or local jurisdiction mandates it.

An air gap provides the highest protection against backflow because it physically separates potable water from the hazard.

A reduced pressure zone assembly is used for high-hazard connections and must be tested annually.

A double check valve assembly is used for low-hazard connections and is testable.

A hose bib vacuum breaker protects a threaded hose connection from backsiphonage.

Backflow can occur by backsiphonage or by backpressure.

Irrigation systems, boiler feed lines, and chemical lines require approved backflow protection.

A cross-connection control program requires testing, records, and repair of testable assemblies.

No direct connection is permitted between potable water and a nonpotable source.

Gas pipe sizing uses appliance Btu/hr input, pipe length, gas specific gravity, and allowable pressure drop.

Natural gas heating value is commonly taken as about 1,000 Btu per cubic foot; LP gas is about 2,500 Btu per cubic foot.

A sediment trap or drip leg is required at each appliance connection.

A shutoff valve must be installed on the gas supply to each appliance in an accessible location.

Gas piping must be pressure tested with air or inert gas before service; test pressure and time depend on code and system pressure.

Gas connectors are limited in length and cannot pass through walls, floors, or ceilings.

CSST gas piping must be bonded as required by the manufacturer and code.

Gas appliances require combustion air and approved venting.