MD Plumber flashcards
MD 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.
- Water column conversion
- One psi equals 2.31 feet of water column, and one foot of head equals 0.433 psi. Plumbers use this to convert static pressure to elevation and to check available pressure at fixtures.
- Water supply fixture unit
- A unit that expresses the probable demand of a fixture. One wsfu approximates one gallon per minute of demand under the Hunter method, used to size water piping from a fixture count.
- Drainage fixture unit
- A unit that expresses the drainage load a fixture imposes. A water closet at 1.6 gallons per flush counts as 3 DFU, a lavatory as 1 DFU, and a floor drain as 2 DFU.
- Standard drain slope
- Quarter inch per foot equals 2 percent, one-eighth inch per foot equals 1 percent, and one-sixteenth inch per foot equals 0.5 percent. Slope percent is rise divided by run times 100.
- Developed length
- The total measured length of a pipe run including the equivalent length added for fittings such as elbows and tees. Sizing tables use developed length, not just straight pipe measurement.
- DWV pressure test
- A completed drainage and vent system is tested with water at a minimum 10-foot head for 15 minutes, or with air at 5 psi for 15 minutes, depending on the adopted code edition.
- Maximum flow velocity
- Domestic cold water is generally limited to about 8 feet per second and hot water to about 5 feet per second. Higher velocities cause erosion, noise, and water hammer.
- Thermal expansion of water
- Water expands roughly 4 percent by volume when heated from 40 to 140 degrees Fahrenheit. Closed systems need an expansion tank or thermal expansion relief to prevent overpressure.
- Federal water closet limit
- Water closets may not exceed 1.6 gallons per flush, urinals 1.0 gallon per flush, and showerheads 2.5 gallons per minute at 80 psi under federal efficiency standards.
- T and P relief valve
- A temperature and pressure relief valve on a water heater opens at 210 degrees Fahrenheit or 150 psi, whichever occurs first. Its discharge pipe runs full size and terminates by gravity.
- Relief discharge termination
- The relief valve discharge must end within 6 inches of the floor or at a safe receptor, with no threads, cap, or valve on the end, and must not discharge where scalding can occur.
- Fixture trap seal
- A trap must hold a water seal between 2 and 4 inches deep. The seal blocks sewer gas while allowing wastewater to pass through the trap to the drainage system.
- Air gap backflow protection
- An air gap is the unobstructed vertical distance between a supply outlet and the flood level rim. It must be at least twice the effective opening, never less than 1 inch.
- Water closet rough-in
- The rough-in is the distance from the finished wall to the centerline of the closet drain. A 12-inch rough-in is standard, with 10-inch and 14-inch versions available.
- Reduced pressure zone assembly
- An RPZ is a testable backflow preventer used for high-hazard connections. It has two check valves and a relief valve that discharges if either check leaks.
- Atmospheric vacuum breaker
- An AVB is a non-testable backflow device for low-hazard, non-continuous use such as hose bibbs. It must be installed at least 6 inches above the highest downstream outlet.
- Building drain versus sewer
- The building drain carries waste from fixtures to a point about 2 feet outside the building wall. The building sewer continues from that point to the public sewer or private system.
- Stack vent definition
- A stack vent is the extension of a soil or waste stack above the highest fixture connection. It runs through the roof to admit air and release sewer gas above the building.
- Vent stack definition
- A vent stack is a vertical vent pipe installed primarily to provide air to a drainage stack. It is separate from the stack vent and connects to the drain at its base.
- Wet vent restrictions
- A wet vent drains one fixture while venting another. It may serve a bathroom group on one floor if sized per the table and the water closet is downstream of the vent connection.
- Air admittance valve rule
- An air admittance valve admits air but does not release it. It must be accessible, installed above the fixture drain, and at least one vent in the system must still run through the roof.
- Storm roof drainage formula
- Roof area in square feet times rainfall intensity in inches per hour, divided by 96, gives the storm flow in gallons per minute used to size leaders and storm drains.
- Backwater valve purpose
- A backwater valve prevents sewage from reversing into a building. It is required on fixtures below the elevation of the next upstream manhole cover where the code so requires.
- Water service sizing method
- Size the water service using fixture units, longest developed length, and available pressure. Subtract elevation loss of 0.433 psi per foot plus meter and fixture losses.
- Maryland plumbing code adoption
- Maryland adopts the International Plumbing Code as the Maryland Plumbing Code under COMAR 09.12.22, with state amendments. Local jurisdictions may adopt stricter local amendments.
- Maryland master plumber license
- The Maryland State Board of Plumbing issues master and journeyman licenses. A master plumber license is required to obtain a plumbing permit and to contract for plumbing work.
- Maryland apprentice hours
- Apprentices complete roughly four years or 7,500 to 8,000 supervised hours, then pass the journeyman exam. Journeyman experience is required before taking the master exam.
- Plumbing permit and inspection
- A plumbing permit must be issued before work begins. Rough-in and final inspections are required, and piping may not be concealed before the rough-in inspection is approved.
- Maryland continuing education
- Maryland requires continuing education for license renewal, commonly 10 hours per two-year cycle for master and journeyman plumbers, including code-update hours set by the Board.
- MHIC license requirement
- A plumbing contractor who performs home improvement work for homeowners must hold a Maryland Home Improvement Commission license in addition to a master plumber license.
- On-site sewage regulation
- On-site sewage disposal in Maryland is regulated by the Maryland Department of the Environment and the local health department. A percolation test and permit are required before installation.
- Backflow testing requirement
- Maryland requires testable backflow assemblies to be tested annually by a certified backflow tester, with the test report filed with the local water authority.