MN Plumber flashcards

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

Building drain definition

The lowest piping of a drainage system that receives waste from inside the building and connects to the building sewer at a point 2 feet outside the building wall.

Fixture unit

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

Minimum drainage slope

Horizontal drainage pipe 2-1/2 inches and smaller must slope at 1/4 inch per foot; pipe 3 inches and larger may slope at 1/8 inch per foot.

Vent stack height

A vent stack must extend at least 6 inches above the roof and be sized according to the drainage stack it serves, with terminals kept away from windows and intakes.

Trap seal depth

A fixture trap must maintain a liquid seal of 2 to 4 inches; the seal prevents sewer gas from entering the building and must be protected by venting.

Grease interceptor purpose

A device installed in a commercial kitchen drain line that separates and retains fats, oils, and grease so they do not clog the building sewer or public system.

Water heater T&P valve

A temperature and pressure relief valve rated for the heater's input that discharges to a safe location, typically terminating 6 to 24 inches above the floor.

Shower valve requirement

Shower valves must be pressure-balancing or thermostatic anti-scald type to limit temperature fluctuation and prevent sudden hot or cold water discharge.

Water closet clearance

A water closet requires at least 15 inches from its centerline to a side wall and 21 inches of clear space from the front of the fixture to an obstruction.

Pressure-reducing valve

A device installed on the water service when street pressure exceeds 80 psi, reducing pressure to a typical 50 to 60 psi to protect fixtures and piping.

Water supply test pressure

The water distribution system must be tested at working pressure for at least one hour; hydrostatic test pressure is typically 100 psi or the system working pressure.

Water-sewer separation

A water main must be at least 10 feet horizontally from a building sewer, or 18 inches below it when crossing, to prevent contamination of potable water.

Air gap backflow protection

The only absolute method of backflow prevention; a physical separation between the water supply outlet and the flood-level rim of a receiving vessel.

RPZ assembly

A reduced pressure zone backflow preventer used for high-hazard connections; it must be tested annually by a certified tester and be accessible for maintenance.

Backflow definition

The reversal of flow in a water system caused by backpressure or backsiphonage, which can allow contaminants to enter the potable water supply.

Roof drain sizing

Roof drains and leaders are sized by roof area and design rainfall intensity in inches per hour, using code tables that relate area to pipe diameter.

Secondary roof drainage

An overflow system such as scuppers or secondary drains required where the primary roof drainage could be blocked, discharging to a visible location.

Sediment trap

A drip leg installed at the appliance connection on a gas line to catch debris and prevent it from entering the appliance controls.

Gas appliance shutoff

A shutoff valve required within 6 feet of each gas appliance, accessible for service, with a union or flanged connection at the appliance.

Gas piping test

Gas piping must be tested at 1.5 times working pressure but not less than 3 psi for 10 minutes on low-pressure systems, per the gas code.

Permit requirement

A permit must be obtained before installing, altering, or replacing a plumbing system; minor repairs such as clearing stoppages are generally exempt.

Rough-in inspection

An inspection of concealed piping before it is covered; water and drainage systems must be tested and approved before concealment.

Licensed plumber scope

Plumbing work must be performed by a licensed master or journeyman plumber, or by an apprentice under direct supervision of a licensed plumber.

Cleanout location

Cleanouts are required at the base of each stack, at the building drain near the sewer, and at changes of direction greater than 45 degrees.

Isometric drawing

A three-dimensional drawing using 30-degree angles to show width, height, and depth; pipe lengths are calculated from true lengths of runs.

45-degree offset multiplier

The length of a 45-degree offset equals the offset distance times 1.414; a 22-1/2 degree offset uses a multiplier of 2.613.

Developed length

The total length of pipe plus fittings measured along the centerline, used to size water supply piping and to order material.

Water softener operation

A water conditioner using ion exchange to remove hardness minerals; it must have a bypass and discharge regeneration waste to an approved location.

Combustion air requirement

Gas appliances must have combustion air provided per manufacturer instructions and the gas code, often through two permanent openings to an interior space.

Storm and sanitary separation

Storm drainage must be kept separate from sanitary drainage; combined systems are allowed only where the public sewer is combined and approved.

Trap arm vent distance

The horizontal distance from a trap to its vent is limited by pipe size, typically 5 feet for 1-1/2 inch, 6 feet for 2 inch, and 8 feet for 3 inch.

Thermal expansion tank

A tank installed on a closed water system to absorb the increased volume caused by heating water, preventing excessive pressure and relief valve discharge.