HI Plumber flashcards
HI Plumber · Build recall with a focused review session.
32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Trap seal depth
- A water seal of 2 to 4 inches (51–102 mm) in a trap prevents sewer gas from entering a building; the maximum permitted depth is 4 inches.
- Confined space oxygen level
- Safe entry requires oxygen between 19.5% and 23.5%; test before entry and ventilate continuously to avoid asphyxiation or explosion.
- DWV air test pressure
- A DWV system air test uses 5 psi (34.5 kPa) held for 15 minutes with no pressure drop; water test uses 10 feet (3 m) of head.
- Hot water scald limit
- Domestic hot water at fixture outlets must not exceed 120°F (49°C); public facilities require scald protection such as thermostatic mixing valves.
- Pipe support spacing
- Copper horizontal pipe must be supported at intervals not exceeding 6 feet (1.8 m); PEX horizontal at 32 inches (813 mm) and vertical at 10 feet (3 m).
- Backflow preventer testing
- A reduced-pressure zone (RPZ) backflow assembly must be tested annually by a certified tester to confirm proper operation and protect potable water.
- Water closet flush volume
- New water closets must not exceed 1.6 gallons per flush (6 Lpf); urinals must not exceed 1.0 gallon per flush (3.8 Lpf).
- Lavatory faucet flow rate
- Lavatory and kitchen faucets are limited to a maximum flow rate of 2.2 gallons per minute (8.3 L/min) at 60 psi.
- Water closet clearance
- A water closet requires at least 15 inches (381 mm) from centerline to side wall and 21 inches (533 mm) of clear space in front.
- Shower valve temperature limit
- Shower valves must be pressure-balancing or thermostatic and limit outlet temperature to 120°F (49°C) to prevent scalding.
- Fixture unit (FU)
- A fixture unit is a measure of load on the plumbing system; a water closet counts as 3 FU drainage and 10 FU supply for private use.
- Floor drain trap primer
- A trap primer or trap seal protection device is required where a floor drain trap may evaporate, maintaining the 2-inch (51 mm) minimum seal.
- Drainage pipe slope
- Drainage pipe must slope 2% (1/4 inch per foot) for 2-inch (50 mm) and smaller pipe; 1% (1/8 inch per foot) for 3-inch (80 mm) and larger.
- Vent stack roof extension
- A vent stack must extend at least 6 inches (152 mm) above the roof, or 12 inches (305 mm) where snow accumulation is expected.
- Maximum trap arm length
- A 2-inch (50 mm) trap arm may be up to 5 feet (1.5 m) long; a 3-inch (80 mm) trap arm may be up to 6 feet (1.8 m) long.
- Building drain cleanout
- A cleanout is required at the junction of the building drain and building sewer and at intervals not exceeding 100 feet (30.5 m).
- Horizontal drainage support
- Horizontal drainage pipe must be supported at intervals not exceeding 4 feet (1.2 m) for 2-inch and smaller, and 10 feet (3 m) for larger pipe.
- Vent vertical rise
- A vent must rise vertically at least 6 inches (152 mm) above the fixture before any horizontal offset to prevent clogging.
- Minimum fixture water pressure
- The minimum static water pressure at a fixture is 8 psi (55 kPa); the maximum static pressure is 80 psi (552 kPa).
- Pressure-reducing valve setting
- A pressure-reducing valve is required when street pressure exceeds 80 psi (552 kPa) and is typically set to 50–60 psi (345–414 kPa).
- Water supply fixture units
- Water supply pipe sizing uses fixture units (WSFU) and equivalent length; a 1/2-inch tube supplies up to 6 WSFU at 60 psi.
- Thermal expansion control
- A closed water system requires an expansion tank sized to system volume to prevent excessive pressure from thermal expansion.
- Backflow prevention hierarchy
- An air gap provides the highest protection; an RPZ is used for high hazard; a double check valve is used for low hazard.
- TPR discharge pipe termination
- A water heater temperature and pressure relief valve discharge pipe must terminate 6–24 inches (152–610 mm) above the floor and not be trapped.
- Plumbing permit requirement
- A plumbing permit is required before installing, altering, or repairing a plumbing system; exemptions vary by jurisdiction and must be verified with the AHJ.
- Model plumbing codes
- The IPC and UPC are model codes; local amendments govern. Always confirm the adopted edition with the authority having jurisdiction (AHJ).
- Rough-in inspection
- A plumbing inspector must inspect rough-in, water test, and final work; approval must be obtained before concealing any piping.
- Backwater valve requirement
- A backwater valve is required on a building sewer subject to backflow; it must be accessible for maintenance and testing.
- Plumbing license requirement
- A plumbing contractor license is required for contracting; a journeyman license is required for individuals performing plumbing work under supervision.
- Labor burden multiplier
- Labor cost equals hourly wage times labor burden (typically 1.25–1.65) times hours; burden includes taxes, insurance, and benefits.
- Change order
- A change order is a written, signed document stating scope, price, and schedule impact; work proceeds only after authorization.
- Retainage
- Retainage is a percentage (typically 5–10%) withheld from payments until substantial completion; it is tracked as accounts receivable.