Plumbing NC II flashcards

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

PPE for solvent cement work

Safety glasses or goggles, gloves resistant to solvent, and a respirator with organic vapor cartridges in poorly ventilated areas. Primer and cement are flammable, so keep ignition sources away.

Confined space oxygen range

Acceptable atmospheric oxygen for entry is 19.5 to 23.5 percent. Below or above this range, ventilate and retest before entry with a calibrated gas meter.

Lockout tagout purpose

Isolates and locks energy sources such as electricity, pressure, or steam before servicing equipment. Verify zero energy by attempting a start and checking gauges before work begins.

Fire extinguisher class C

For fires involving energized electrical equipment. Use a non-conductive agent such as carbon dioxide or dry chemical. Never apply water while the equipment is energized.

Drawing scale 1:100

One unit on the drawing represents 100 units on site. A 30 mm line on paper equals 3,000 mm or 3 m in the building. Check the scale bar before measuring.

Floor drain symbol

A circle with a cross inside represents a floor drain on plumbing plans. A circle with a diagonal line is a cleanout, and a square with a circle is a vent terminal.

Drawing versus specification

Drawings show geometry, location, and routing. Specifications define material grades, jointing, testing, and fixture types. The specification governs quality unless a later revision states otherwise.

Riser diagram purpose

A schematic elevation showing vertical pipe runs, stack connections, vent routing, and fixture levels. It is not to scale and is read with the floor plan for layout.

Fitting take-off

The distance from the fitting center to its face, subtracted from center-to-center pipe length to obtain the actual cut length. Values differ by fitting type and size.

45 degree offset formula

Offset equals travel times 0.707; travel equals offset times 1.414. For a 22.5 degree offset, travel equals offset times 2.613. Use for pipe routing around obstructions.

Slope fall formula

Fall equals run length times gradient. A 12 m run at 1:50 falls 0.24 m. Express gradient as a ratio such as 1:50 or as a percentage such as 2 percent.

3-4-5 square check

A triangle with sides in ratio 3-4-5 has a right angle between the short sides. Use it to set out square pipe runs and confirm layout before cutting or drilling.

Copper tube types K L M

Type K is thickest for underground and heavy duty; L is standard for supply; M is thin wall for above ground; DWV is thinnest for drainage. Match type to service.

Schedule 40 versus 80 PVC

Schedule 80 has thicker walls and a higher pressure rating than schedule 40 at the same nominal size. Use schedule 80 for high-pressure or industrial service.

Wye branch fitting

A Y-shaped drainage fitting that joins a branch at a shallow angle to promote smooth flow and reduce clogging. Preferred over a tee on horizontal drainage runs.

PTFE tape application

Wrap tape clockwise around male threads, two to three turns, leaving the first thread bare. Apply tape only to male threads; never to female threads or to flare connections.

NPT thread taper

Standard pipe threads are tapered at 1:16, so the joint tightens as it engages. A properly cut thread engages a fitting by hand for two to three turns.

Solvent weld cure time

After joining PVC or CPVC, allow the joint to cure before pressure testing. Cure time increases with pipe diameter and decreases with temperature; follow the cement manufacturer's table.

Soldering versus brazing

Soldering uses filler melting below 450 degrees Celsius; brazing uses filler above that. Potable water joints require lead-free solder and approved flux.

Copper bend radius rule

Minimum bend radius is typically three to five times the pipe diameter. Use a spring or lever bender and annealed copper for tight bends to avoid flattening or kinking.

Pressure reducing valve setting

Installs downstream of the meter when supply pressure exceeds about 550 kPa or 80 psi. Typical setting is 350 to 550 kPa to protect fixtures and reduce noise.

Fixture unit method

Assigns fixture units to each fixture, sums them, and converts to probable demand using a code table. The demand then sizes the pipe to limit velocity and friction loss.

Water hammer arrestor

A device with a trapped air or piston chamber installed near quick-closing valves to absorb pressure surges. It prevents banging and protects joints from fatigue.

Hydrostatic test pressure

Test water supply piping at 1.5 times working pressure or per code, commonly 690 kPa or 100 psi, held for at least one hour with no pressure drop.

DWV slope for 100 mm pipe

A 100 mm or 4 inch drain is typically laid at 1:100 or 1 percent. Smaller pipe such as 50 mm uses 1:50 or 2 percent. Confirm the value in the applicable code.

Trap seal depth

The water seal in a fixture trap is normally 50 to 100 mm or 2 to 4 inches. A shallower seal evaporates easily; a deeper seal is not permitted because it traps air.

Stack vent height

The vent extending above the roof must rise at least 150 mm or 6 inches above the roof surface, or above the depth of snow where snow loads apply.

Cleanout placement

Required at the base of each stack, at changes of direction greater than 45 degrees, and at intervals of about 15 m or 50 ft on horizontal runs. It must remain accessible.

Water closet rough-in

The distance from the finished wall to the centerline of the closet flange, commonly 300 mm or 12 inches. Verify against the fixture manufacturer's rough-in sheet before setting.

Flush valve vacuum breaker

Must be installed at least 150 mm or 6 inches above the fixture rim to prevent backflow. Test by shutting off the valve and confirming the breaker opens and drains.

T&P relief valve discharge

The temperature and pressure relief valve on a water heater must discharge to a safe point through a full-size pipe, with no valve or trap, and terminate visibly.

Gurgling drain cause

Usually a blocked or undersized vent, not a drain blockage. Air cannot enter behind the flowing water, so the trap seal is siphoned. Inspect the vent before rodding.