CPD Water Supply & Distribution Systems 3

Question 1

When sizing a cold water branch serving a bathroom group (lavatory, water closet, bathtub), what WSFU value is commonly assigned per the IPC?

Accepted Answer

5 WSFU

Answer

The IPC assigns 5 WSFU to a full bathroom group (lavatory, water closet, and bathtub/shower) for sizing purposes.

Question 2

Which formula relates head loss to flow velocity, pipe diameter, and friction factor in water distribution design?

Accepted Answer

Darcy-Weisbach equation

Answer

The Darcy-Weisbach equation calculates head loss due to friction as a function of the Darcy friction factor, pipe length, diameter, and flow velocity.

Question 3

What is the primary purpose of a pressure-reducing valve (PRV) in a water supply system?

Accepted Answer

To reduce high street pressure to a safe working range

Answer

A PRV reduces high incoming street pressure (often 80–150 psi) to a safe, code-compliant working pressure typically set at 60–80 psi.

Question 4

Galvanic corrosion in a water supply system is most likely to occur when:

Accepted Answer

Dissimilar metals are connected without dielectric isolation

Answer

Galvanic corrosion occurs at the junction of dissimilar metals in the presence of an electrolyte (water), driving electrochemical current that degrades the anodic metal.

Question 5

For a booster pump system in a high-rise, the pump is typically selected to provide adequate pressure at the:

Accepted Answer

Most remote and highest fixture in the zone

Answer

Booster pumps must overcome both elevation head and pipe friction to deliver adequate pressure at the most hydraulically remote and elevated fixture.

(CPD) Certified Plumbing Designer Practice Test

(CPD) Certified Plumbing Designer Practice Test

CPD Water Supply & Distribution Systems 3