AR Plumber cheat sheet

A master plumber may obtain plumbing permits, contract for plumbing work, and supervise others; a journeyman plumber performs plumbing work only under a master's direction.

Apprentices must be registered with the state board and work under direct supervision of a licensed plumber while accumulating the required work hours.

The Arkansas State Plumbing Code adopts the International Plumbing Code as the base document, with state amendments that control where the two differ.

Plumbing permits are issued by the local authority having jurisdiction (AHJ); where no local plumbing program exists, the Arkansas Department of Health administers permits and inspections.

A license is required before performing plumbing work for compensation; owner exemptions generally apply only to owner-occupied single-family dwellings.

A license must be renewed before its expiration date; working on an expired license is a violation subject to civil penalties.

Revised plans that affect code compliance must be submitted to the AHJ and approved before the changed work is installed.

A permit is required before installing, altering, replacing, or relocating a plumbing system; ordinary minor repairs such as replacing a faucet washer are exempt.

The permit holder must request rough-in inspection before piping is covered and final inspection after fixtures are set and tested.

Drainage and vent systems are tested with a 10-foot (3 m) hydrostatic head of water, or with 5 psi of air held for 15 minutes.

Water distribution piping is tested with potable water at the working pressure for at least 15 minutes and must show no leakage or pressure drop.

A certificate of occupancy or use is withheld until the plumbing final inspection passes.

The code official may accept alternative materials, methods, or designs when they comply with the intent of the code and the approval is documented in writing.

Construction documents must show fixture locations, pipe sizes, and riser diagrams before a plumbing permit is issued.

One water-supply fixture unit represents about 1 gpm of demand; one drainage fixture unit (DFU) approximates the drainage load of a lavatory.

Common DFU values: water closet 3, lavatory 1, bathtub or shower 2, kitchen sink 2, floor drain 2, washing machine 2.

Slope rule: horizontal drainage pipe 2½ inches and smaller at ¼ inch per foot; 3-inch through 6-inch pipe at ⅛ inch per foot.

Grade in percent = rise ÷ run × 100; ¼ inch per foot equals approximately 2 percent slope.

Travel of a 45-degree offset equals the offset multiplied by 1.414; two 45-degree bends and a 90-degree change are solved the same way.

Pressure conversion: psi × 2.31 = feet of water column head, so 1 psi is about 2.31 ft of head.

Gallons of water in a pipe = 0.0408 × (inside diameter in inches)² × length in feet.

Developed length includes the measured run plus an allowance for fittings; it is used with fixture units to size water supply piping.

Residual flowing pressure must be at least 8 psi at fixtures generally, and at least 15 psi at flushometer valves.

Design velocity limits are about 8 fps in cold-water piping and 5 fps in hot-water piping to control noise and erosion.

A pressure-reducing valve is required where static pressure exceeds 80 psi; a thermal expansion tank is required on a closed system.

Minimum building water supply size is typically ¾ inch for a single-family dwelling served by a ¾-inch meter.

Water service pipe must be buried below the local frost depth and at least 12 inches deep where frost is not a design factor.

Water hammer arrestors are installed near quick-closing valves such as flushometers and solenoid valves.

Longest-length and available-pressure methods determine pipe size from the meter or source to the farthest fixture.

A backflow preventer is required wherever a piping connection could create a cross-connection with the potable supply.

Federal flow limits: water closet 1.6 gal per flush, urinal 1.0 gal per flush, showerhead 2.5 gpm at 80 psi, lavatory and kitchen faucet 2.2 gpm.

A water closet requires at least 15 inches from its centerline to a sidewall and at least 30 inches of clear width.

Accessible lavatory rims must be no higher than 34 inches above the finished floor, with knee and toe clearance below.

Every fixture must be trapped except fixtures with an integral trap; the trap must remain accessible for cleaning.

Fixture tailpieces must extend at least 4 inches below the fixture, and slip joints or unions must be accessible.

Faucets and fittings must be installed so hot is on the left and cold on the right, matching the identification on the trim.

Fixtures must be set level and secure, with supply stops installed on the fixture supply so the fixture can be serviced independently.

Horizontal drainage pipe is installed at a uniform slope: ¼ inch per foot for 2½-inch and smaller, ⅛ inch per foot for 3- through 6-inch.

Cleanouts are required at the base of each stack, at horizontal changes of 45 degrees or more, and at intervals not exceeding 100 feet.

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

A vertical change of 45 degrees or more in a horizontal drain requires a long-turn fitting or two 45-degree bends.

Trap arm length limits: 1¼ inch - 5 ft, 1½ inch - 6 ft, 2 inch - 8 ft, 3 inch - 12 ft.

The building drain carries waste to the building sewer; the building sewer begins about 2 feet outside the building wall.

A backwater valve is required where fixtures are below the level of the street or where the sewer can surcharge.

Drainage piping installed in or under a slab must be protected against shear and supported at code-required intervals.

Every trap must be vented; a vent may not be smaller than 1¼ inch nor less than half the size of the drain it serves.

Vent terminals must extend at least 6 inches above the roof and must be at least 10 feet horizontally from, or 3 feet above, windows, doors, and air intakes.

Each vent stack must extend to the outdoors; air admittance valves are allowed only where the code permits and must remain accessible.

Wet venting lets one fixture drain vent another fixture, but only where both fixtures are on the same floor and the sizing rules are met.

Common vents require the fixtures to be on the same floor and connected at the same level, with the vent sized to the largest drain served.

A horizontal vent must rise at least 6 inches above the flood-level rim of the fixture before any offset.

The connection between a vent and a drain must be taken above the flood-level rim of the fixture served.

Trap seals must be at least 2 inches and not more than 4 inches deep, and each trap must be level and self-cleaning.

S-traps, drum traps (except where allowed), and double-trapping of a single fixture are prohibited.

Grease interceptors are required for food-service fixtures that discharge fats, oils, and grease into the drainage system.

An air gap is the only absolute backflow protection and is required for high-hazard connections such as a hose bibb feeding a chemical container through a direct connection.

A reduced pressure zone (RPZ) assembly protects against high hazard; a double check valve assembly protects against low hazard.

A pressure vacuum breaker protects against backsiphonage but not against backpressure.

Traps and cleanouts must be accessible, and each trap may serve only one fixture except where the code allows a combination.

A temperature and pressure (T&P) relief valve is typically set to open at 210°F and 150 psi, and its rating must match the heater's input.

The T&P discharge pipe must be the same size as the valve outlet, drain by gravity, and terminate 6 inches above the floor or outside the building.

Domestic hot water delivered to fixtures must not exceed 120°F unless a tempering or mixing valve limits the temperature.

A thermal expansion tank is required on a closed system protected by a backflow preventer or check valve.

A drain pan with a drain line is required where leakage from the heater could cause damage or where the heater is installed in an attic or ceiling space.

Gas-fired heaters require combustion air, proper venting, and a sediment trap on the gas supply line.

Relief valve discharge must not be trapped, plugged, or reduced in size, and the valve must not be relocated from the heater's designated opening.

Storm drainage must discharge to a storm sewer or other approved point of disposal and may never connect to the sanitary sewer.

Roof drain and leader sizing is based on the design rainfall rate and the tributary roof area in square feet.

Secondary (overflow) roof drains are required for large roofs and must be set higher than the primary drains.

Fuel gas piping is sized by the longest-length method using each appliance's Btu/h load and the allowable pressure drop.

Gas piping is pressure-tested with air at not less than 3 psi, or at the pressure specified by the code, for the required holding time.

A sediment trap and a listed shutoff valve must be installed ahead of each gas appliance.

Gas piping may not be concealed inside ducts, plenums, or chimneys.

A sewage ejector is required when plumbing fixtures are located below the level of the public sewer.