Water Supply Systems Flashcards

What is the Water Supply Fixture Unit (WSFU) value for a standard residential water closet with a flush tank?

Answer: 2.5

A flush-tank water closet is rated at 2.5 WSFU, reflecting its moderate water demand during the fill cycle after flushing.

When sizing water supply piping, what is the primary factor that determines friction loss?

Answer: Flow velocity and pipe length

Friction loss in water supply piping is primarily determined by the flow velocity (related to flow rate and pipe diameter) and the total developed length of the pipe run, including equivalent lengths for fittings.

What is the maximum flow velocity recommended in water supply piping to minimize noise and erosion?

Answer: 2.4 m/s (8 fps)

A maximum velocity of 2.4 m/s (8 fps) is recommended for water supply piping. Higher velocities cause excessive noise, erosion of pipe walls, and increased risk of water hammer.

What material is commonly used for water service piping entering a building below grade in Canada?

Answer: Copper Type K

Copper Type K is the heaviest wall thickness of copper tubing and is commonly used for underground water service because of its durability and resistance to soil corrosion.

At what temperature must a thermostatic mixing valve (TMV) limit the output for public lavatory faucets to prevent scalding?

Answer: 49°C

Thermostatic mixing valves for public lavatories must limit the water temperature to a maximum of 49°C (120°F) to prevent scalding injuries, especially for vulnerable populations.

What is the purpose of a pressure-balancing valve in a shower installation?

Answer: To maintain consistent water temperature during pressure fluctuations

A pressure-balancing valve senses changes in hot and cold supply pressures and adjusts flow to maintain a consistent mixed temperature, preventing sudden scalding or cold-water shock.