CPD Water Supply & Distribution Systems 2 — Questions and Answers
Question 1: What is the minimum water pressure required at the point of use for most plumbing fixtures per the Uniform Plumbing Code?
- 15 psi
- 20 psi (Correct answer)
- 25 psi
- 30 psi
Correct answer: 20 psi
The Uniform Plumbing Code requires a minimum of 20 psi at the point of use for most fixtures to ensure adequate flow.
Question 2: Which type of pipe material is most resistant to dezincification in water supply systems?
- Yellow brass
- Red brass
- Dezincification-resistant (DZR) brass (Correct answer)
- Silicon bronze
Correct answer: Dezincification-resistant (DZR) brass
DZR brass alloys are specifically formulated with inhibitors to resist dezincification in aggressive water conditions.
Question 3: In a zone-pressure distribution system for a tall building, what is the typical maximum zone height to limit static pressure?
- 6 floors
- 8 floors
- 10 floors (Correct answer)
- 12 floors
Correct answer: 10 floors
Zones are typically limited to approximately 10 floors (about 100 ft) to keep static pressure within acceptable limits of around 45 psi.
Question 4: What ASTM standard covers copper water tube Type L used in plumbing systems?
- ASTM B42
- ASTM B88 (Correct answer)
- ASTM B251
- ASTM B302
Correct answer: ASTM B88
ASTM B88 is the standard specification for seamless copper water tube, covering Types K, L, and M.
Question 5: Which method is used to calculate the design flow rate in a water distribution system based on fixture unit values?
- Hardy Cross method
- Hunter's curve method (Correct answer)
- Darcy-Weisbach equation
- Manning formula
Correct answer: Hunter's curve method
Hunter's curve (Hunter's method) converts water supply fixture units (WSFU) into probable simultaneous flow rates (gpm).
Question 6: A recirculating hot water system is designed primarily to:
- Increase water pressure at fixtures
- Eliminate the need for a water heater
- Deliver hot water quickly and reduce waste (Correct answer)
- Reduce cold water hammer
Correct answer: Deliver hot water quickly and reduce waste
Recirculating systems keep hot water circulating through the distribution loop so it arrives quickly at fixtures, reducing both wait time and water waste.
Question 7: What is the purpose of a vacuum breaker on a hose bibb connection?
- To regulate water pressure
- To prevent backflow by siphonage (Correct answer)
- To filter sediment from the supply
- To reduce water hammer
Correct answer: To prevent backflow by siphonage
A vacuum breaker on a hose bibb prevents backflow by breaking the siphon if the supply pressure drops below atmospheric pressure.
CPD Water Supply & Distribution Systems 2
What is the minimum water pressure required at the point of use for most plumbing fixtures per the Uniform Plumbing Code?